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1
Van, Wyk Elizabeth Joy. "Pineal-adrenal gland interactions in search of an anti-stressogenic role for melatonin." Thesis, Rhodes University, 1993. http://hdl.handle.net/10962/d1004115.
Abstract:
The multiple functions of the pineal gland have been collectively interpreted as constituting a general anti-stressogenic role. The adrenal glands play a central role in maintaining homeostasis. The major neuroendocrine consequence of long-term stress is elevated circulating glucocorticoid levels. In this study, the effect of chronic, oral hydrocortisone treatment on pineal biochemistry was investigated in male Wi star rats of the albino strain. The results show that seven days of oral hydrocortisone treatment endows the pineal gland with the ability to increase melatonin synthesis in organ culture. The increase is accompanied by a rise in NAT activity, cyclic AMP levels and enhanced specific binding to the pineal B-adrenergic receptors. It appears that hydrocortisone sensitizes the pineal gland to stimulation by B-adrenergic agonists. thus rendering the pineal more responsive to B-adrenergic agonists. Further studies were directed at demonstrating an anti-stressogenic function for the pineal gland by investigating whether the principal pineal indole, melatonin. could protect against the deleterious effects of elevated. circulating drocortisone levels. The results show that chronic, oral hydrocortisone treatment significantly increases liver tryptophan pyrrolase activity. The catabolism of tryptophan by tryptophan pyrrolase is an important determinant of tryptophan availability to the brain, and therefore, brain serotonin levels. The findings show that melatonin inhibits basal and hydrocortisone-stimulated liver tryptophan pyrrolase apoenzyme activity in a dose-dependent manner. This inhibition suggests that melatonin may protect against excessive loss of tryptophan from circulation and against deficiencies in the cerebral serotinergic system which are associated with mood and behavioural disorders. It was shown that another deleterious effect of chronic hydrocortisone treatment is a significant increase in the number of glutamate receptors in the forebrain of male Wistar rats. The increase in receptor number observed in this study is probably due to an increase in the synthesis of glutamate receptors and is associated with a marked reduction in the affinity of the glutamate receptors for glutamate. possible to demonstrate an receptor number or the For practical reasons, it was not effect of melatonin on either glutamate affinity of glutamate receptors for glutamate in rat forebrain membranes. In view of the neurotoxic effect of glutamate in the eNS, the functional significance of recently described glutamate receptors in the pineal gland was investigated. The results show that 10-4 M glutamate significantly inhibits the isoprenaline-stimulated synthesis of N-acetylserotonin and melatonin in organ culture when the pineal glands were pre-incubated with glutamate for 4 hours prior to stimulation with isoprenalin and when glutamate and isoprenaline were administered together in vitro. GABA, a glutamate metabolite could not mimic the decrease in isoprenalinestimulated melatonin, and it is likely that the observed effects were directly attributed to glutamate. Incubation of the pineal gland with 10-4 M glutamate in organ culture did not affect HIOMT activity in pineal homogenates, but significantly elevated both basal and isoprenaline-stimulated NAT activity. It was concluded that glutamate only inhibits melatonin synthesis in intact pineal glands and not in pineal homogenates. The present study has provided further support for an interaction between the pineal and the adrenal glands. There is an ever increasing likelihood that melatonin is an anti-stressogenic hormone and that the pineal gland may have a protective role to play in the pathology of stress-related diseases.
2
Porter, Mark. "The role of melatonin and the pineal gland in the photoperiodic control of reproduction and smoltification in Salmonid fish." Thesis, University of Stirling, 1996. http://hdl.handle.net/1893/26676.
Abstract:
The timing of seasonal events in salmonids is thought to be controlled by endogenous circannual rhythm(s) which are entrained by the seasonally-changing daylength. This thesis investigates the role of the pineal gland in the perception of the photoperiodic zeitgeber and the subsequent transmission of this information to the brain through neural or hormonal pathways. Melatonin biosynthesis by isolated rainbow trout pineal glands was shown to exhibit a differential response to graded photic or thermal stimuli. In vitro experiments were carried out at 10±0.50 C as this provided optimum melatonin levels for radioimmunoassay analysis together with a pineal longevity of up to 14 days. By incorporating a variety of light intensities into the light/dark cycle, the salmonid pineal gland was shown to synthesise significantly different levels of melatonin even when light levels varied by only 0.5 lux. Early work on the salmonid pineal suggested it was unresponsive to red light, having a spectral sensitivity which peaks between 500 and 550 nm, this study has revealed that the pineal is also capable of responding to wavelengths between 660 to 800 nm, at which pineal reception was previously thought to be severely limited. No endogenous rhythm of melatonin secretion was observed within the isolated rainbow' trout pineal gland. Both Atlantic salmon and Atlantic halibut pineals exhibited elevated levels- of melatonin in response to the dark phase, however, they also appeared capable of maintaining this rhythm in the absence of external stimuli. This provides the first evidence that the daily rhythm of melatonin production in these species is controlled by an endogenous circadian oscillator located within the pineal II gland. The pinealectomy technique developed during the course of this thesis successfully abolished the diel rhythm of melatonin secretion and, together with an enucleation procedure, enabled the pineal to be identified as the predominant source of the dark phase melatonin in Atlantic salmon and rainbow trout. However, the lateral eyes did contribute significantly to plasma melatonin levels in both species. Long term experiments, involving pinealectomy and/or implantation of melatonin, were used to investigate the role of the pineal gland in the timing of rainbow trout maturation and smoltification in Atlantic salmon. Pineal removal at the summer or winter solstices did not significantly alter the timing of smoltification. However, significantly higher blood serum osmolarities following seawater challenge tests were observed in smolts implanted with melatonin. This, together with a significant growth increase shown by salmon parr within 1 month of implantation, indicates that melatonin may directly affect the development of salmonids through either a physiological response or by influencing the entrainment of endogenous rhythms. The increased growth observed in the implanted parr is also thought to be responsible for the unimodal population distribution and high percentage of S1 smolts within this group. Investigations into the role of the pineal gland in the timing of spawning in rainbow trout found that pineal removal at the summer solstice caused a 6 week delay in spawning time compared to intact fish. However, no clear effects on spawning time were observed when pineal removal, with or without melatonin implantation, was performed to coincide with the change from long to short daylengths which is known to advance spawning times. Although no significant effect in spawning times was observed between groups, the 4 month spawning period of the pinealectomised group compared to 1 month in the shampinealectomised fish also suggested that pineal removal may have caused a desynchronisation in spawning time. Pinealectomy and/or implantation did not alter egg size or fecundity, but plasma calcium levels were shown to be significantly lower in the pinealectomised trout over the spawning period. To summarise, the pineal gland and melatonin play a significant role in salmonid development. It is suggested that melatonin can influence biological systems through a direct physiological action while the pineal gland may synchronise circannual events through the photoneuroendocrine transduction of seasonal environmental information.
3
Mchunu, Bongani Isaac. "The effect of appetite suppressants on pineal function." Thesis, Rhodes University, 1994. http://hdl.handle.net/10962/d1004098.
Abstract:
The pineal gland has become the subject of considerable investigation as it provides a productive experimental model for studying circadian rhythms and regulation of end organs. In the rat, the pineal gland provides a convenient model for investigating the noradrenergic receptor system and the effects of various drugs on this system. The effect of appetite suppressants on the rat pineal gland function is described. Appetite suppressants increase melatonin synthesis in organ cultures of rat pineal glands. This effect appears to be mediated by noradrenaline acting on β-adrenoceptors on the pinealocyte membrane. When β-adrenoceptors are blocked, the appetite suppressant-induced rise in melatonin synthesis is prevented. Depletion of noradrenaline in sympathetic nerve terminals also prevented the appetite suppressant-induced rise in melatonin synthesis. Activation of β-adrenoceptors is followed by a rise in N-acetyltransferase activity via a cyclic adenosine monophosphate second messenger system. The effect of appetite suppressants on the activity of liver tryptophan pyrrolase was also investigated. The activity of this enzyme is an important determinant of tryptophan availability to the brain and consequently of brain serotonin levels. The results show that appetite suppressants inhibit both holoenzyme and total enzyme activities of tryptophan pyrrolase. This finding suggests that appetite suppressants may act by inhibiting tryptophan pyrrolase activity thereby increasing brain serotonin, a phenomenon known to be associated with anorexia. There are two possible mechanisms by which appetite suppressants inhibit tryptophan pyrrolase activity. Firstly, these agents, being drugs of dependence, may increase liver NADPH concentrations which inhibit pyrrolase activity. Secondly, appetite suppressants may act on the pineal gland to stimulate melatonin synthesis. Melatonin inhibits pyrrolase activity in a dose-dependent manner. This inhibition will elevate plasma tryptophan levels which result in a rise in brain serotonin synthesis. The present study suggests a possible relationship between the pineal gland and appetite centres in the hypothalamus. Melatonin may have a direct effect on appetite centres since food restriction is associated with an increased melatonin binding in the hypothalamus. If this possible relationship can be extended, melatonin can open new possibilities for the control of food intake and consequently, of pathological obesity.
4
Machado, Sanseray da Silveira Cruz. "Caracterização do eixo imune-pineal: glândula pineal como alvo para lipopolissacarídeo (LPS)." Universidade de São Paulo, 2010. http://www.teses.usp.br/teses/disponiveis/41/41135/tde-06122010-100938/.
Abstract:
O fator de transcrição nuclear kappa B (NFKB), central na resposta inflamatória, é constitutivamente expresso em glândulas pineais de rato. A inibição da translocação nuclear deste fator em pineais de rato por corticosterona potencia, enquanto que a inibição pela citocina fator de necrose tumoral (TNF) inibe a síntese de melatonina por inibição da transcrição da Aa-nat. Esta redução da produção noturna de melatonina está implicada em favorecer a montagem da resposta inflamatória. Embora dados da literatura sugerirem redução da produção de melatonina durante processos infecciosos, não há evidências diretas da habilidade da glândula pineal em reconhecer o lipopolissacarídeo (LPS), a endotoxina da membrana de bactérias gram-negativas. Esta dissertação investigou se a glândula pineal de ratos expressa receptores para o reconhecimento do LPS e estabeleceu possíveis mecanismos de ação desta endotoxina na glândula pineal de ratos. Nossos resultados demonstram que a glândula pineal expressa de maneira constitutiva os receptores CD14 e o TLR4. LPS induz a translocação nuclear dos dímeros p50/p50 e p50/RelA e a síntese de TNF em glândulas cultivadas. A máxima produção de TNF no meio de cultura é coincidente com a máxima expressão do receptor TNFR1 em pinealócitos. Além disso, LPS inibe a síntese de N-acetilserotonina e melatonina. Em conclusão, neste estudo, demonstramos que a pineal é alvo para o componente de bactérias gram-negativas LPS, reforçando a proposta de que esta glândula reconhece e gera respostas a moléculas que sinalizam a montagem da resposta inflamatória.Nuclear factor-kappa B (NFKB), a pivotal player in inflammatory responses, is constitutively expressed in the pineal gland. Corticosterone inhibits pineal NFKB leading to an enhancement of melatonin production, while tumor necrosis factor (TNF) leads to inhibition of Aa-nat transcription and the production of N-acetylserotonin (NAS) in cultured glands. The reduction of nocturnal melatonin surge favors the mounting of the inflammatory response. Despite these data, there is no clear evidence of the ability of the pineal gland to recognize molecules that signal infection. This study investigated whether the rat pineal gland expresses receptors for lipopolysaccharide (LPS), the endotoxin from the membranes of gram-negative bacteria, and to establish the mechanism of action of LPS. Here we show that pineal glands possesses both CD14 and toll-like receptor 4 (TLR4), membrane proteins that bind LPS and trigger the NFKB pathway. LPS induced the nuclear translocation of p50/p50 and p50/RELA dimers and the synthesis of TNF. The maximal expression of TNF in cultured glands coincides with an increase in the expression of TNF receptor 1 (TNFR1) in isolated pinealocytes. In addition, LPS inhibited the synthesis of N-acetylserotonin and melatonin. Therefore, the pineal gland transduces gram-negative endotoxin stimulation by producing TNF and inhibiting melatonin synthesis. Here we provide evidence to reinforce the idea of an immune-pineal axis, showing that the pineal gland is a constitutive player in the innate immune response.
5
Welman, Alan David. "The pineal gland as a model to elucidate the primary mode of action of sympathoactive agents." Thesis, Rhodes University, 1991. http://hdl.handle.net/10962/d1001610.
Abstract:
An attempt was made to use the pineal gland as a model for the study of the primary mode of action of sympathoactive agents. Two drugs were investigated, viz. alpha-methyldopa and ephedrine whose mode of action is not entirely clear. Organ cultures of pineal glands from rats treated chronically with alpha-methyldopa showed enhanced conversion of radioactive serotonin to melatonin (aMT) , as well as its precursor Nacetylserotonin (aHT). This treatment was also found to raise Nacetyltransferase (NAT) activity. These increases associated with alpha-methyldopa treatment were further enhanced by the beta-adrenergic agonist, isoproterenol, suggesting a supersensitivity-type effect occurring at the level of the beta-receptor. A subsequent binding study, however, showed a decrease in beta-receptor binding with exposure to alpha-methyldopa, providing mitigating evidence against the occurrence of a supersensitivity phenomenon. It is possible that a metabolite of alpha-methyldopa acts as an alpha 1 and beta-adrenergic agonist, resulting in greater melatonin (aMT) and N-acetylserotonin (aHT) synthesis than by a beta-adrenergic agonist, isoproterenol. Combined treatment of pineals with alpha-methyldopa and an alphareceptor blocker, phentolamine, resulted in melatonin (aMT) , Nacetylserotonin (aHT) , and N-acetyltransferase (NAT) activity levels which were lower than those obtained with alpha-methyldopa treatment alone, thus confirming the alpha-adrenergic activity of the metabolite of alpha-methyldopa. Additional pineal metabolites were isolated and measured simultaneously in the organ culture experiments. Organ cultures of rat pineal glands treated with ephedrine showed raised levels of melatonin (aMT) and N-acetylserotonin (aHT). Treatment with ephedrine also produced raised N-acetyltransferase activity. A further enhancement of these parameters was induced by norepinephrine, suggesting a supersensitivity-type effect occurring at the level of the beta-adrenergic receptor. Rats were treated with reserpine (a norepinephrine depleter) and the pineals exposed to ephedrine. Endogenous norepinephrine normally released by the action of ephedrine was thus absent, and under these conditions, levels of melatonin (aMT) and N-acetylserotonin (aHT) were reduced. N-acetyltransferase (NAT) activity was also reduced, but maintained levels pointing to substantial adrenergic activity of ephedrine as well as norepinephrine released by virtue of the drug's action. A subsequent binding study showed a decrease in beta-adrenergic receptor binding with exposure to ephedrine and a further decrease in ephedrine treated pineals from reserpine treated rats, thus ruling out the occurrence of a supersensitivity phenomenon. It is possible that both ephedrine and released norepinephrine have alpha- and beta-receptor activity. Additional pineal metabolites were isolated and measured in the organ culture experiments. A 16-hour time profile of the production of melatonin (aMT) and N-acetylserotonin (aHT) with norepinephrine and ephedrine treatment provided useful information regarding the course of action of the two agents. A pineal cell-culture system was developed and exposed to ephedrine and norepinephrine. N-acetyltransferase (NAT) activity levels measured after exposure to these agents were raised, confirming the adrenergic activity of both in the model. Finally, an HPLC system coupled to a UV detector was used in an attempt to measure melatonin (aMT) extracted from pineal organ culture media. The results showed that melatonin could be measured by this method, however, a more sensitive detection system was recommended for future work.
6
Vu, Hung Quoc. "Short Term Effects of External Electric Fields on Electrical Activity of the Pineal Gland in Rats." Thesis, University of North Texas, 1996. https://digital.library.unt.edu/ark:/67531/metadc277728/.
Abstract:
The effects of short term exposure (5 minutes) to EEFs at relatively high dosages (10, 25, 39, kV/m) on the electrical activity in rat pineal glands was studied.
Daytime and nighttime recordings were taken from an implanted microelectrode in the gland. The data show that (1) both the activity and frequency were enhanced when the
animals were exposed to EEFs at 39 kV/m continuously and discontinuously; (2) the later condition yielded a sustained increase (36%) whereas the former a brief (10 sec) increase. This enhancement was statistically significant under both conditions (day and night). The effects observed were thought to be due to membrane alterations either in the pineal gland itself or in the neural inputs to the gland.
7
Dwyer, Virginia Michelle Gregory 1955. "A STUDY OF PINEAL GLAND POLYPEPTIDES AND PROTEINS BY POLYACRYLAMIDE GEL ISOELECTRIC FOCUSING (PAG-IEF) AND TWO-DIMENSIONAL ELECTROPHORESIS (2DE) (BRAIN REGIONS)." Thesis, The University of Arizona, 1986. http://hdl.handle.net/10150/276560.
8
Eason, Jason Shane. "An investigation into cholinergic interactions in the rat pineal gland." Thesis, Rhodes University, 1993. http://hdl.handle.net/10962/d1004109.
Abstract:
The mammalian pineal gland is mainly innervated by the sympathetic nervous system which modulates the activity of indole pathway enzymes and the secretion of pineal hormones. Recently researchers have demonstrated and characterized the presence of muscarinic cholinergic receptors in the pineal gland. However the role of these receptors remains unclear. In an attempt to investigate the role of cholinergic receptors in the pineal gland, a number of studies were carried out on the various steps in the indole metabolic pathway, using various agents which act on the cholinergic system. Investigations using pineal organ cultures showed that stimulation of these muscarinic cholinergic receptor sites with a parasympathomimetic agent, a rise in levels of aHT occurred without a concomitant increase in aMT levels. Further organ culture experiments using the cholinergic agonist acetylcholine and anticholinesterase agent physostigmine, produced a similar rise in aHT without altering aMT levels. This acetylcholine-induced rise in aHT levels were not altered by the ganglion blocking agent hexamethonium whilst the antimuscarinic agent atropine prevented the acetylcholine-induced rise in aHT levels. Thesefindings suggest that cholinergic agents may play a role in regulating indoleamine synthesis in the pineal gland. Cyclic-AMP assay studies showed that acetylcholine increases pineal cAMP levels significantly and does not influence the isoproterenol-induced cAMP rise in the pineal gland. The cAMP regulator cAMP-phosphodiesterase (cAMP-PDE) was found to increase significantly in the presence of the anticholinesterase agent physostigmine. NAT enzyme studies revealed that physostigmine does not affect NAT enzyme levels significantly and HIOMT studies showed that this agent does not inhibit HIOMT activity. The mechanism by which acetylcholine and physostigmine are able to cause a increase in aHT and not aMT levels needs to be researched further. Acetylcholinesterase enzyme assay studies revealed that the AChE enzyme undergoes a diurnal rhythm in the pineal gland with activity being higher during the day and lower at night. Investigations using the drug reserpine showed that this rhythm is not under the control of the sympathetic nervous system. Further research needs to be done however, in determining whether or not this enzyme is present in the pineal gland to regulate the levels of acetylcholine interacting with muscarinic receptors in the gland, or for some other reason. Choline acetyltransferase studies demonstrate the presence of the enzyme in the rat brain cerebral cortex as well as showing that melatonin increases ChAT enzyme activity in this tissue. This suggests that melatonin plays a role in cholinergic transmission there. ChAT activity could not be measured in the pineal gland however. Muscarinic receptor binding studies also carried out on rat brain cerebral cortex show that melatonin enhances cholinergic receptor affinity and receptor number in this tissue. In summary, data presented herein concur with proposals that: i) the cholinergic system affects the indole metabolic pathway by causing a rise in aRT but not aMT levels. ii) cholinergic agonist acetylcholine causes cAMP levels to rise with a concomitant increase in cAMP-PDE levels. iii) the enzyme acetylcholinesterase undergoes a diurnal rhythm in the pineal gland which is not under the control of the sympathetic nervous system. iv) the activity of the enzyme choline acetyltransferase is increased by melatonin in the rat brain cerebral cortex suggesting that melatonin facilitates cholinergic transmission in this tissue. v) melatonin enhances cholinergic receptor affinity and receptor number in the cerebral cortex of rat brain.
9
Machado, Sanseray da Silveira Cruz. "Caracterização dos receptores tipo Toll em glândulas pineais de rato e sua implicação no entendimento do eixo imune-pineal." Universidade de São Paulo, 2015. http://www.teses.usp.br/teses/disponiveis/41/41135/tde-30032015-093506/.
Abstract:
A glândula pineal regula diversos ritmos biológicos e respostas de defesa em indivíduos hígidos através da síntese noturna de melatonina. Por outro lado, é sabido que processos inflamatórios reduzem a produção deste hormônio na glândula pineal. Neste estudo utilizamos um arranjo de qPCR para investigar a expressão circadiana de 84 genes relacionados a sinalização via receptores do tipo toll e NF-κB em glândulas pineais de rato. Confirmamos ainda, a expressão de 14 proteínas em pinealócitos através de ensaios de imunocitoquímica. Nossos resultados indicam que 70 genes inflamatórios são expressos ritmicamente na glândula pineal de ratos, enquanto 7 não são expressos e outros 7 genes são expressos, mas sem ritmicidade. Grande parte dos genes examinados apresenta padrão de expressão circadiana com maior conteúdo transcricional na fase de claro, atingindo a máxima expressão no final desta fase. Após o apagar das luzes, a expressão destes genes é rapidamente reduzida. Um possível envolvimento do ritmo de glicocorticóides endógeno sobre o padrão dessa expressão gênica foi avaliado através do bloqueio de GR por mifepristona, o que induziu a regulação da expressão de 13 genes e redução do conteúdo plasmático de melatonina no ZT18. Ainda, avaliamos o efeito da ativação dos TLR1, TLR2 e TLR6 sobre a glândula pineal e observamos que zimosan e Pam3CSK4 ativam a via do fator de transcrição NF-κB e bloqueia a síntese de melatonina induzida por noradrenalina in vitro. Por fim, utilizamos o modelo de obseidade induzido por dieta hipercalórica para avaliar se o processo inflamatório de baixa intensidade regula a síntede se melatonina in vivo. Observamos que nestas condições, a dieta hipercalórica induz rápido aumento no peso corporal e redução da produção noturna de melatonina. O efeito protetor da melatonina sobre o ganho de peso induzido por dieta foi testado através da restauração da melatonina na água de beber noturna de animais expostos à dieta. Em conjunto, nossos resultados indicam que genes inflamatórios são expressos ritmicamente na glândula pineal de ratos e influenciam a produção circadiana de melatonina via reconhecimento de padrões moleculares associados à patógenos ou sinais de perigoThe pineal gland regulates several circadian rhythms as well as immune responses in healthy animals via rhythmic production of melatonin, the hormone of darkness. On the other hand, nocturnal melatonin levels are reduced in the course of inflammation. To date, it remains to be clear the mechanisms by which the immune system affects pineal melatonin synthesis. Here we used a qPCR array profiler to investigate circadian gene expression of 84 genes related to Toll-Like Receptors and Nuclear Factor kappa B signaling. We also examined the expression of 14 proteins in pinealocytes by immunocytochemistry. Our results indicate rhythmic expression of 70 inflammatory genes, while 7 genes were not expressed and 7 were expressed without rhythmicity. The overall majority of genes tested showed a pattern of expression with a cumulative diurnal increase that peaks at the light phase of ZT12 followed by a fast reduction in the expression as soon as the light is turned off. The possible involvement of endogenous glucocorticoid rhythm in the modulation of pineal\'s inflammatory gene expression were tested by blocking Glucocorticoid Receptor (GR) using mifepristone. This procedure modulated the expression of 13 genes. In addition, the blockade of GR reduced the circulating melatonin levels at ZT18. The activation of TLR1, TLR2 and TLR6 induces the nuclear translocation of NF-κB signaling and blocks noradrenaline-induced melatonin synthesis in vitro. In addition, high-fat diet feeding increases body weight and reduce the circulating melatonin levels at ZT18. The protective role of melatonin in diet-induced weight gain was also determined by giving these rats melatonin in their drinking water at night. Altogether, our results highlight that inflammatory genes are transiently expressed in the rat pineal gland and influences the daily fluctuation of melatonin synthesis
10
Cheung, M. C. Kenneth. "Role of pineal gland and melatonin in the development of scoliosis." Click to view the E-thesis via HKUTO, 2007. http://sunzi.lib.hku.hk/HKUTO/record/B39557492.
11
Cheung, M. C. Kenneth, and 張文智. "Role of pineal gland and melatonin in the development of scoliosis." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2007. http://hub.hku.hk/bib/B39557492.
12
Luke, Jennifer Anne. "The effect of fluoride on the physiology of the pineal gland." Thesis, University of Surrey, 1997. http://epubs.surrey.ac.uk/895/.
13
Olivieri, Gianfranco. "The regulation of Serotonin N-acetyltransferase in the rat pineal gland." Thesis, Rhodes University, 1993. http://hdl.handle.net/10962/d1004112.
Abstract:
The synthesis of the pineal hormone, melatonin, is finely regulated by the pineal enzyme serotonin N-acetyltransferase (NAT). In the absence of light, the activity of NAT is markedly enhanced by the release of nor-adrenaline from sympathetic nerve endings in the pineal. Exposure of animals to light during darkness causes a sudden and dramatic reduction in the activity of NAT. The present study investigated a possible mechanism for this sudden decline in NAT activity. These investigations included the determination of the effects of S-adenosylmethionine (SAM), adenosine nucleotides and calcium on NAT activity. In vitro experiments using SAM showed that pineals pre-incubated with SAM prior to adrenergic stimulation did not significantly alter NAT activity or pineal indoleamine metabolism. However, measurement of pineal cyclic AMP showed that SAM exposure reduced the adrenergic-induced rise in pineal cyclic AMP. Experiments using adenosine 5'-monophosphate (5'-AMP) showed that this nucleotide enhanced both dark- and isoproterenol-induced NAT activity. Adenosine 5'-triphosphate (A TP), on the other hand, reduced NAT activity with a concomitant reduction in pineal indoleamine metabolism. Exposure of isoproterenol-stimulated pineals in organ culture to propranolol resulted in a marked rise in ATP and adenosine 5'-diphosphate (ADP) synthesis accompanied by a decline in 5'-AMP levels as compared with pineals treated with isoproterenol alone. This then implies that exposure of animals to light could cause a change in pineal nucleotide levels. Since nucleotide levels are also controlled by calcium, experiments were carried out to determine the effect of calcium on pineal NAT activity. These experiments showed that ethyleneglycol-bis-N,N,N,N,-tetraacetic acid (EGTA) enhanced NAT activity whilst calcium reduced the activity in pineal homogenates, implying that calcium may act directly on NAT to regulate its activity. Exposure of pineal glands in organ culture to the calmodulin antagonist R24571 caused a rise in pineal cyclic AMP levels with a concomitant decrease in cAMP-phosphodiesterase activity. This was, however, accompanied by a decline in Nacetyl serotonin and melatonin synthesis. These findings implicate a number of factors in the regulation of pineal NAT activity. A mechanism for the regulation of pineal NAT is proposed.
14
Burton, Susan Frances. "A study of the effects of the pineal hormone, melatonin, on dopaminergic transmission in the central nervous system of rats." Thesis, Rhodes University, 1990. http://hdl.handle.net/10962/d1001463.
Abstract:
Dopamine mechanisms in the central nervous system are important in the control of both normal and abnormal motor function. The recent observations in both animal and human studies, that melatonin, the principal hormone of the pineal gland, may have a role in the control of movement and the pathophysiology of movement disorders, have given rise to the concept that melatonin may have a modulatory influence on central dopaminergic neurotransmission. This study makes use of three animal behavioural models as well as a biochemical model of central dopaminergic function to further investigate the concept. Results from studies using the biochemical model, which investigated the effect of melatonin on dopamine and apomorphine stimulation of dopamine-sensitive adenylate cylase, suggest that melatonin is neither a competitive antagonist nor agonist at the D₁ receptor level, although the possibility of physiological stimulation or antagonism is not excluded. In behavioural studies, prior melatonin mg/kg administration (1 and 10 (8M) ip) inhibited apomorphine induced stereotypy and locomotor activity in normal rats, and apomorphine-induced rotational behaviour in 6-hydroxydopamine and quinolinic acid lesioned rats. The possibility that these results may have physiological significance is borne out by the observation that, under enviromental lighting conditions that are associated with raised endogeous melatonin levels, apomorphine- induced stereotypy and locomotor activity is attenuated. The general conclusion is that melatonin has an inhibitory influence on central nervous system dopaminergic function, suggesting therefore, that the pineal gland and melatonin may have a role in the pathophysiology and treatment of movement and behavioural disorders associated with dopaminergic dysfunction
15
Bailey, Michael J. "Functional genomics of the avian circadian system." Texas A&M University, 2004. http://hdl.handle.net/1969.1/3318.
Abstract:
The genetic identification of molecular mechanisms responsible for circadian rhythm generation has advanced tremendously over the past 25 years. However the molecular identities of the avian clock remain largely unexplored. The present studies seek to determine candidate clock components in the avian species Gallus domesticus. Construction and examination of the transcriptional profiles of the pineal gland and retina using DNA microarray analysis provided a clear view into the avian clock mechanism. Investigation of the pineal and retina transcriptomes determined the mRNA profiles of several thousand genes over the course of one day in LD (daily) and one day in DD (circadian) conditions. Several avian orthologs of mammalian clock genes were identified and many exhibited oscillating patterns of mRNA abundance including several of the putative avian clock genes. Comparison of the pineal transcriptional profile to that of the retina revealed several intriguing candidate genes that may function as core clock components. Including the putative avian clock genes and several others implicated in phototransduction, metabolism, and immune response.
A more detailed examination of several candidate photoisomerase/photopigment genes identified from our transcriptional profiling was conducted. These include peropsin (rrh), RGR-opsin (rgr), melanopsin (opn4) and cryptochrome 2 (cry2) genes. This analysis revealed several interesting patterns of mRNA distribution and regulation for these genes in the chick. First, the mRNA of all 4 genes is located within the Inner Nuclear Layer (INL) and Retinal Ganglion cell Layers (RGL) of the ocular retina, where circadian photoreception is present. Second, opn4 and cry2 mRNA is expressed in the photoreceptor layer of the chick retina where melatonin biosynthesis occurs. Lastly, the mRNA for all 4 candidate photopigment genes is regulated on a circadian basis in the pineal gland. As a whole these data yield significant insight into the mechanisms of the avian circadian system and present several candidate genes that may function to integrate photic information, and/or regulate circadian rhythm generation in birds.
16
Закрутько, Анна Анатоліївна, Мар'яна Іванівна Кривчанська, and Мар'яна Іванівна Грицюк. "Morphometric analysis of pineal gland condition at melatonin administration on the background of beta-adrenoreceptors blockade." Thesis, 2nd International Medical Students' Congress Sarajevo 2016, February 4 th – February 7th 2016, Sarajevo Bosnia and Herzegovina, 2016. Р. 25, 2016. http://dspace.bsmu.edu.ua:8080/xmlui/handle/123456789/11915.
17
Закрутько, А. О., Мар'яна Іванівна Кривчанська, and Мар'яна Іванівна Грицюк. "Morphometric analysis of pineal gland condition at melatonin administration on the background of beta-adrenoreceptors blockade." Thesis, 2nd International Medical Students' Congress Sarajevo 2016, February 4 th – February 7th 2016, Sarajevo Bosnia and Herzegovina, 2016. – 184 р, 2016. http://dspace.bsmu.edu.ua:8080/xmlui/handle/123456789/11625.
18
McCallaghan, Johannes Jacobus. "An investigation into the anxiolytic properties of melatonin in humans." Thesis, Rhodes University, 1999. http://hdl.handle.net/10962/d1003250.
Abstract:
The purpose of this project was to investigate the role of melatonin in the pathophysiology of anxiety in humans. The literature study confirmed the intimate relationship between serotonin and melatonin. Melatonin is not only able to act as an agonist (in physiological concentrations) and an antagonist (at higher concentrations) on serotonin receptors but via control of brain pyridoxal kinase activity might have an effect on GABA, serotonin, dopamine and norepinephrine synthesis. A clinical trial to investigate melatonin's effect on anxiety in humans was conducted as a pilot study. Thirty patients complaining of anxiety participated in a liN of 1" double blind placebo controlled trial. During the experiment each subject was thus exposed to melatonin and a placebo for a week at a time on two occasions. During the first phase of the experiment, (Pair '1) patients showed a statistically significant reduction in their anxiety levels during the first period (P1P1), which was not the case during the second period (P1P2). The improvement however continued during the second phase of the experiment (Pair 2) so that there was also a statistically significant improvement during P 2 P 2 (Period 2 / Pair 2) when placebo was administered. It could not conclusively be shown that melatonin was responsible for the improvement in the patients' anxiety. The explanation for these results suggests thelt the improvement was due to a: 1) placebo effect throughout, 2) psychotherapeutic effect due to contact with a clinician, 3) melatonin induced phase shift in the patient's endogenous melatonin response curve, 4) combination of all 3 options. This pilot study lays the groundwork for a much more exhaustive study in which the melatonin of the patients is determined before melatonin is administered, the role of the clinician is clarified and the most appropriate time for melatonin administration is sought .
19
Petrilli, Camila Lopes. "Regulação da atividade da glândula pineal por estimulação purinérgica." Universidade de São Paulo, 2012. http://www.teses.usp.br/teses/disponiveis/41/41135/tde-01052013-140517/.
Abstract:
A biossíntese de MEL pela pineal envolve a conversão da serotonina a NAS pela enzima AA-NAT, seguida demetilação da NAS pela enzima HIOMT gerando a MEL. A ativação β-adrenérgica é essencial e a co-estimulação de receptores P2Y1 potencia a produção de NAS induzida por noradrenalina. Neste trabalho avaliamos o efeito da estimulação de receptores P2Y1 sobre a produção de MEL induzida pela estimulação β-adrenérgica. A co-estimulação purinérgica com ADP, levou a potenciação da produção de NAS induzida por ISO e a inibição do conteúdo de MEL de maneira dependente de concentração. Em extratos nucleares de pineais estimuladas com ADP, a translocação nuclear de AP-1 foi observada, não havendo alteração significativa na translocação nuclear dos dímeros NF-κB p50/p50 e p50/RelA. PDTC, inibidor de NF-κB, não alterou o conteúdo de NAS e MEL em pineais em cultura estimuladas com ISO e ADP. A expressão gênica e a atividade enzimática de AA-NAT e HIOMT não foram alteradas pela co-estimulação com ISO e ADP. O bloqueio seletivo dos receptores P2Y1 por A3\'P5\'P inibiu de maneira dependente de concentração o efeito potenciador do ADP sobre a produção de NAS induzida por ISO, mas não reverteu a inibição observada nos níveis de melatonina. Estes resultados apontam para um mecanismo diferencial de modulação da produção de NAS e MEL abrindo novas perspectivas ao estudo dos mecanismos regulatórios da produção de MEL e seus metabólitosThe biosynthesis of MEL by the pineal gland involves the conversion of serotonin to NAS by the enzyme AA-NAT, followed by methylation of NAS by the enzyme HIOMT generating MEL. The activation of β-adrenergic receptors is essential and the co-stimulation of P2Y1 receptors potentiates noradrenaline-induced NAS production. In this study we evaluated the effect of P2Y1 receptors stimulation on the production of MEL synthesis induced by β-adrenergic stimulation. Purinergic co-stimulation with ADP potentiated ISO-induced NAS production and inhibited melatonin content in a concentration dependent manner. In nuclear extracts from stimulated pineal glands with ADP, the nuclear translocation of AP-1 was observed, with no significant change in the nuclear translocation of the NF-κB dimers p50/p50 and p50/RelA. PDTC, an inhibitor of NF-κB, did not alter the content of NAS and MEL in cultured pineal glands co-stimulated with ISO and ADP. ISO and ADP co-stimulation did not alter the transcript and enzyme activity of AA-NAT and HIOMT. The selective blockade of P2Y1 receptors by A3\'P5\'P inhibited, in a concentration-dependent manner, the potentiating effect of ADP on ISO-induced NAS production but did not change the inhibition observed on MEL levels. These results suggest a differential mechanism on the modulation of NAS and MEL production opening new perspectives to the study of the regulatory mechanisms involved in the biosynthesis of MEL and its metabolites
20
Cecon, Erika. "Fator de transcrição NFKB em glândulas pineais de ratos." Universidade de São Paulo, 2010. http://www.teses.usp.br/teses/disponiveis/41/41135/tde-17092010-111758/.
Abstract:
A glândula pineal é um órgão neuroendócrino que tranduz a informação fótica ambiental em sinal humoral pela produção noturna do hormônio melatonina. Recentemente, trabalhos de nosso grupo apontam para a existência de um eixo imunepineal, que considera não só a influência que a melatonina exerce sobre células imunocompetentes, mas também o efeito de mediadores da inflamação sobre a atividade biossintética da glândula. Foi demonstrado que a síntese de melatonina pode ser inibida por agentes pró-inflamatórios e potenciada por substâncias antiinflamatórias. Ambos os efeitos são dependentes da via do fator de transcrição NFKB, sendo que seu conteúdo nuclear nos pinealócitos está inversamente relacionado à produção de melatonina. Esta via de sinalização do NFKB foi inicialmente relacionada somente aos processos de resposta imunológica. Entretanto, seu envolvimento em processos fisiológicos tem sido cada vez relatado. A detecção desta via em glândulas pineais e da sua potencialidade em modular a síntese de melatonina induziu à pesquisa do possível papel fisiológico de NFKB neste órgão, objetivo da presente dissertação. Glândulas pineais obtidas de animais hígidos apresentam a via NFKB constitutivamente ativada, sendo que o conteúdo nuclear deste fator apresenta-se de forma rítmica ao longo do dia. Na fase de claro ambiental há um acúmulo nuclear gradativo, mas assim que inicia a fase de escuro os níveis nucleares de NFKB são bruscamente reduzidos e mantidos baixos durante toda a fase de escuro. Essa dependência do ritmo de NFKB com relação à informação fótica ambiental é, na verdade, consequência do efeito de ritmos hormonais atuantes sobre a essa via. A corticosterona induz a queda abrupta nos níveis nucleares deste fator no início do escuro, enquanto que a própria melatonina produzida pela pineal mantém essa inibição sobre a translocação nuclear de NFKB durante o restante da noite. Assim, postula-se que a regulação deste fator garanta a funcionalidade fisiológica da glândula, uma vez em que alterações no seu conteúdo nuclear resultam em alterações na produção de melatonina. Além disso, tais dados abrem novas perspectivas quanto aos mecanismos regulatórios da atividade da pineal por agentes que atuam via NFKBThe pineal gland is a neuroendocrine organ that transduces the environmental photic information into humoral signals through the nocturnal production of melatonin. Recently, our group have showed the existence of a Immune-pineal axis, that consider not only the melatonin effects on immunocompetent cells, but also the effect of inflammatory mediators on the biosynthetic activity of the pineal gland. It was shown that the melatonin production can be inhibited by pro-inflammatory agents and potenciated by the anti-inflammatory ones. Both effects rely on the NFKB nuclear factor pathway, since its nuclear content in pinealocytes is inversely related to melatonin production. The NFKB pathway was firstly related only to the immune response processes. However, its role in several physiological functions is well documented nowadays. The detection of this pathway in pineal glands and the detection of its modulatory effects on melatonin production lead to the investigation of the putative physiologic role of NFKB in the gland, which was the aim of this project. Pineal glands from healthy animals show NFKB pathway constitutively activated and its nuclear contents show a rhythm through out the 24h of the day. During the light phase, the amount of NFKB increases continuously and a sharp drop occurrs when lights are turned off and there is low level of nuclear NFKB all night long. Actually, the relation between the NFKB rhythm and the light/dark cycle is dependent on endogenous hormonal rhythms. Corticosterone induces the abrupt drop in nuclear NFKB at the beginning of the dark phase, while the pineal melatonin keeps this inhibitory effect through the night. Therefore, it is suggested that the control of NFKB nuclear translocation is required to the physiological function of pineal gland, since any alteration on its nuclear content results in alteration on melatonin production. In addition, these data opens new perspectives on the regulatory mechanisms of the pineal biosynthetic activity by agents that act through the NFKB pathway
21
Boyd, Clinton Shane. "An investigation into dopamine-melatonin interactions in the rat Corpus striatum and pineal gland: a possible pineal-striatal axis." Thesis, Rhodes University, 2000. http://hdl.handle.net/10962/d1003965.
Abstract:
Dysfunction of central dopaminergic systems has been implicated in neuroendocrine, neurodegenerative and psychiatric disorders. Monoamine oxidase and catechol-Omethyltransferase represent the key catabolic enzymes of dopamine, terminating neurotransmission following synaptic release of this catecholamine. Thus, both enzymes have been associated with the pathology of dopaminergic systems and represent therapeutic targets elf enormous clinical importance. Some neuroendocrine and circadian effects of melatonin have been attributed to an antidopamimetic effect of this pineal hormone in the hypothalamus and pituitary. Furthermore, both melatonin and dopamine modulate the behavioural output of the mesencephalic dopaminergic pathways of the basal ganglia, including movement disorders. However, the biochemical basis for the tonic inhibitory effect of melatonin in the nigro-striatal pathway has been poorly delineated. Thus, this study determined whether melatonin influences dopaminergic function in the corpus striatum of the Wistar rat by modulating monoamine oxidase and catecholO- methyltransferase activity. Reciprocally, the putative existence of an intrapineal dopaminergic system was investigated by determining the effect of selective dopaminergic agents, R-( -)apomorphine, haloperidol and dopamine, on indole metabolism of the pineal gland. The akinetic state of drug-induced catalepsy was employed as an animal model of Parkinson's disease to probe the neurotransmitter systems involved in the behavioural effects of melatonin. Indole metabolism was a reliable indicator of state-dependent metabolic fluxes in pineal gland function. These included a robust diurnal and seasonal variation in N-acetylserotonin and melatonin biosynthesis, and photoperiod- and drug-induced alterations of Inftabolism. The predominant changes could be attributed to an effect on serotonin N-acetyltransferase activity and/or the melatoninl5-methoxytryptophol ratio. Pineal 5-methoxyindole biosynthesis was determined primarily by the bioavailability of the corresponding 5-hydroxyindole and its affinity for hydroxyindole-O-methyltransferase. Evidence was found for the negative feedback or paracrine control of pineal indole metabolism by melatonin. A high inter-individual variability was observed in the biosynthesis of N-acetylserotonin and melatonin biosynthesis, and the weight of the pineal glands. Accordingly, the rats could be classified as either high or low capacity producers of these two indoles. R-(-)-apomorphine and dopamine in vitro, but not acute haloperidol in vivo, had dose- and phase-dependent effects on pineal indole metabolism. The predominant effect was a suppression of the scotophase-dependent induction ofN-acetylserotonin and melatonin biosynthesis by dopamine and R-( -)-apomorphine. It is postulated that these agonists inhibited nocturnal N-acetyltransferase activity via postsynaptic pineal D2 or D2-like receptors. The observed modulatory nature of the intrapineal dopaminergic system suggests that dopamine may be involved in the long-term regulation of pineal indole biosynthesis. Several lines of evidence are presented that the activity of striatal monoamine oxidase A and catechol-O-methyltransferase, represented predominantly by the soluble isoform, is statedependent and regulated in vivo by endogenous melatonin. Firstly, both enzymes showed a daynight variation in activity. Secondly, acute and subchronic administration and photoperiod manipulation studies indicated that both exogenous and endogenous melatonin inhibited each enzyme in a chronotypic fashion, with a more robust effect against catechol- -methyltransferase. The intensity of the in vivo effects was critically dependent on the dose, duration, route and the phase-timing of administration during the light dark cycle, and the length of the exposure to constant light. Melatonin in vitro had no effect on basal or Mg2+ -induced catechol-Omethyltransferase activity. Thus, it is proposed that the in vivo effects of the hormone can be attributed to a time-dependent change in the amount of active molecules of this enzyme. In contrast, melatonin and numerous other endogenous indolic compounds were found to be reversible inhibitors of striatal monoamine oxidase A in vitro. Structure-activity modeling revealed that the 5-methoxy moiety on the indole nucleus and substitution of the free primary amine of these compounds were the principal determinants of the potency and time-dependency of inhibition. Thus melatonin most likely has a direct inhibitory effect in vivo at the level of the active site of monoamine oxidase A. Exogenous melatonin alone had no cataleptogenic potential whereas a variety of behavioural responses were observed following intraperitoneal administration of y-hydroxybutyrate. The latter responses were state-dependent with day-night variations in intensity. Furthermore, yhydroxybutyrate stimulated melatonin biosynthesis during the photophase both in vitro and in vivo. These results point to a possible involvement of melatonin in the behavioural and neurochemical effects of y-hydroxybutyrate. Thus the general conclusion is that dopamine and melatonin display functional antagonism at the level of the pineal gland and corpus striatum of the Wistar rats. Therefore melatonin may be an important homeostatic modulator of dopaminergic neurotransmission throu~out the central nervous system. Furthermore, the putative existence of a functional pineal-striatal axis would greatly strengthen the argument for a holistic concept of brain homeostasis. The ability of endogenous melatonin to regulate monoamine oxidase A and catechol-O-methyltransferase may represent an alternative strategy for the treatment of disorders associated with these enzymes.
22
Banoo, Shabir. "Neuropharmacological interactions in the rat pineal gland a study of antidepressant drugs." Thesis, Rhodes University, 1992. http://hdl.handle.net/10962/d1003222.
Abstract:
The rat pineal gland provides a convenient model for investigating nor adrenergic receptor neurotransmission and the effects of various drugs on these processes in health and disease. The effect of a variety of antidepressant drugs on rat pineal gland function following acute and chronic administration is described. Antidepressants from several different classes increase melatonin synthesis in rat pineal gland cultures when administered acutely. This effect appears to be mediated by noradrenaline acting on postsynaptic β-adrenoceptors. Activation of these receptors, in turn, activates the enzyme serotonin N-acetyltransferase via a cyclic adenosine monophosphate (cAMP) second messenger system. Serotonin N-acetyltransferase catalyses the rate-limiting conversion of serotonin to melatonin. Blockade of postsynaptic β-adrenoceptors prevents the antidepressant-induced increase in melatonin synthesis. The possibility that atypical antidepressants as well as those that selectively inhibit serotonin reuptake may increase melatonin synthesis via a β-adrenoceptor mechanism is discussed. In contrast, however, antidepressants from different classes have variable effects on rat pineal gland function when administered repeatedly. Chronic treatment with antidepressants that selectively inhibit noradrenaline reuptake appear to down-regulate the β-adrenoceptor system while, simultaneously, increasing melatonin output. Atypical antidepressants and those that selectively inhibit serotonin reuptake appear to be without these effects when administered repeatedly. The pineal gland of normal rats may therefore not represent a suitable model for evaluating the biochemical effects of chronic antidepressant treatment. In an attempt to investigatc pineal gland function in rats with "model depression" , antidepressants were administered to chronically reserpinized rats. Treatment with reserpine produced an increase in the density of pineal β-adrenoceptors. In addition, pineal cyclic AMP accumulation and N-acetyltransferase activity were increased in reserpinized rats following exogenous catecholamine stimulation. Reserpine, by depleting intraneuronal catecholamine stores, prevented the nocturnal induction of N-acetyltransferase activity and reduced the synthesis of melatonin in pineal gland cultures. A variety of antidepressants, irrespective of their acute pharmacological actions, reversed these effects when administered chronically to resepinized rats. Acute antidepressant administration was not associated with a reversal of the reserpine-induced effects. These findings provide additional evidence against the hypothesis that antidepressant drugs act by reducing noradrenergic neurotransmission and casts doubt on the importance of β-adrenoceptor down-regulation in the mechanism of antidepressant action. The possibility that the pineal gland of the reserpinized rat may represent an alternative model for evaluating antidepressant therapies is discussed.
23
Sousa, Cláudia Emanuele Carvalho de. "Caracterização do eixo imune-pineal: mecanismo de ação do controle da função pineal pela citocina pró-inflamatória TNF." Universidade de São Paulo, 2011. http://www.teses.usp.br/teses/disponiveis/41/41135/tde-27042011-131503/.
Abstract:
O TNF atua diretamente sobre a pineal inibindo a via biossintética da melatonina. De forma semelhante o LPS, potente ativador da resposta imune inata, tem efeito inibitório sobre a produção de melatonina e seu precursor. A supressão da síntese noturna de melatonina é admitida de forma a permitir a montagem da resposta inflamatória, tanto durante o dia como à noite. Dados do grupo tem demonstrado que o NFKB é um fator constitutivamente expresso na glândula pineal e que o ritmo diário de translocação pode ser determinante para o início da síntese de melatonina. A inibição de sua ativação potencia a síntese de melatonina enquanto que fatores que classicamente promovem a sua ativação inibem esta produção. Nesta dissertação, verificamos as moléculas envolvidas no reconhecimento e na de sinalização desta citocina na pineal. Demonstramos que a pineal está apta a responder ao TNF, células gliais da pineal e as células secretoras, os pinealócitos, expressam constitutivamente o receptor TNF-R1. O TNF promove a translocação nuclear dos dímeros p50/p50 e p50/RelA do NFKB em glândulas pineais em cultura. Confirmamos a ativação desta via em pinealócitos pela análise da proteína inibitória IKB. Vimos que a ativação desse fator é essencial para expressão da iNOS e a produção de NO induzida por TNF em pinealócitos isolados. Além disso, mostramos que o TNF promove a redução da expressão do receptor TNF-R1 na membrana de pinealócitos. Em resumo, mostramos neste trabalho que a pineal está instrumentalizada a responder ao TNF, e que os pinealócitos são alvos diretos para o seu reconhecimento. Confirmamos a relevância do fator NFKB na resposta da pineal em situações de injúria, ampliando o conceito de que a pineal está apta a detectar moléculas do processo inflamatório.TNF acts directly on the pineal gland by inhibiting the biosynthesis of melatonin. Similarly, LPS, a potent activator of the innate immune response has an inhibitory effect on the production of melatonin and its precursor. The suppression of nocturnal melatonin synthesis is admitted to allow the full mounting of the inflammatory response both during the day and night. Data from our laboratory have shown that the NFKB is constitutively expressed in the pineal gland and that the daily rate of translocation can be determinant for the onset of melatonin synthesis. Inhibition of their activation potentiates melatonin synthesis whereas factors that promote its activation classically inhibit this production. In this dissertation we find the molecules involved in recognition and signaling of this cytokine in the pineal. We demonstrated that the pineal is responsive to TNF, the pineal glial cells and secretory cells, the pinealocytes, constitutively express the TNF-R1. TNF promotes nuclear translocation of p50/RelA and p50/p50 NFKB dimers in the pineal glands in culture. We confirmed the activation of this pathway in pinealocytes by analyzing the inhibitory protein IKB. We have seen that the activation of this factor is essential for iNOS expression and NO production induced by TNF in isolated pinealocytes. Furthermore we show that TNF promotes the reduction of the expression of TNF-R1 receptor on the membrane of pinealocytes. In summary, we show here that the pineal is instrumented to respond to TNF and that the pinealocytes are direct targets for its recognition. We confirm the relevance of NFKB in the pineal response in situations of injury extending the concept that the pineal is able to detect molecules in the inflammatory process and respond accordingly.
24
Mançanares, Celina Almeida Furlanetto. "Morfologia da glândula pineal de gambás (Didelphis sp)." Universidade de São Paulo, 2004. http://www.teses.usp.br/teses/disponiveis/10/10132/tde-11042007-142919/.
Abstract:
A glândula pineal deve ser analisada e estudada em animais da fauna brasileira, para que dados da pesquisa básica possam ser aplicados em novas técnicas de manejo reprodutivo destes animais, inclusive em cativeiro, face à íntima relação deste órgão fotorreceptor com o ciclo reprodutivo. Para este estudo, foram utilizados 10 gambás (Didelphis sp), provenientes do Departamento de Anatomia da USP e UNIFEOB, já mortos e fixados. Nenhum animal foi submetido a situações de dor/sofrimento e ao sacrifício de sua vida. A glândula pineal foi encontrada em todos animais estudados e apresentou-se de diminutas dimensões, não sendo possível, portanto descrever-lhe características macroscópicas. Através da análise microscópica pudemos localizar a glândula no espaço correspondente ao plano mediano, em relação ao encéfalo, rostral e dorsalmente aos colículos rostrais, ventralmente aos hemisférios cerebrais e caudalmente à comissura habenular. Consiste de uma evaginação do teto do diencéfalo e mostra-se em forma de "U" invertido. Comparativamente a características de glândulas pineais de outras espécies animais, a do Didelphis genus, que estudamos, revela peculiaridades tanto em relação ao seu tamanho, apenas perceptível microscopicamente, quanto ao fato de apresentar suas células secretoras dispersas também em áreas vizinhas. Tais peculiaridades motivam reflexões sobre o papel funcional da glândula, na espécie considerada.The pineal gland must to be analyzed and studied in animals of the Brazilian fauna, to apply the data obtained in the basic research of new techniques at reproductive handling of these animals, including in captivity, in view of the close relation between this photoreceptor organ with the circadian and reproductive cycle. For this study, 10 opossums (Didelphis sp), had been used, already died and fixed, proceeding from the Department of Anatomy of USP and UNIFEOB. None animals were submitted to pain/suffering situations and their no life sacrifice. The pineal gland was found in all studied animals with and smaller dimention, not possessing, therefore goss features. By microscopy analysis we could found the gland in the correspondent space to median plan in relation to the encephalon, rostral and dorsally to the rostral coliculli, ventrally to the brain hemispheres and caudally to the habenular comissure. That consistes like an evagination of the diencephalons tectum showing the "U" shape. Considering other pineal glands and its features in different species, we note the gland is extremely small for it specie, possessing dispersed secretory cells in the nervous parenchyma whose form, sufficiently irregular, suggests a small hormonal performance to them in the Didelphis genus. Comparativelly of the pineal gland feactures in different animals, the Didelphis genus, that was our aim, shows pecualirity as in size relation, only microscopically visible, than the fact to prossessing dispased secretory cells, with irregular surrounding shape. All pecualiarites suggest refletion about the function action of the gland at the studied specie.
25
Brown, Clint. "In vitro effects of three organic calcium channel blockers on the rat pineal gland." Thesis, Rhodes University, 1992. http://hdl.handle.net/10962/d1003223.
Abstract:
The calcium signal has emerged as an imponant component of intracellular regulation. Pineal function was thought to be slowed by the prominent calcification seen with increasing age, but recently it has been shown that calcium plays a crucial role in the adrenergic regulation of the gland. Beta-adrenoceptor stimulation increases melatonin (aMT) synthesis by increasing the activity of cyclic 3 '-5' adenosine mono phosphate (cAMP). Cyclic-AMP regulates the production of the pineal hormone, melatonin, from serotonin via the rate-limiting enzyme N-acetyltransferase (NAT). Increased intracellular cAMP is essential to the adrenergic induction of NAT. Noradrenaline(NA)also elevates pinealocyte cyclic guanosine monophosphate (cGMP). Adrenergic regulation of these cyclic nucleotides involves both α₁ - and β-adrenoceptors. Beta-adrenoceptor stimulation is an absolute requirement. Alphal-adrenoceptor activation, which is ineffective alone, serves to amplify the β-stimulated cAMP and cGMP responses via a positive effect on a Ca²⁺⁻/ phospholipiddependent protein kinase (Protein kinase-C) and a net influx of Ca²⁺ into the pinealocyte. Previous studies suggest the use of organic calcium channel blockers (CCBs) as probes of calcium-mediated processes. Applying this concept, the study set out to investigate the influence of a representative of each of the structurally diverse groups of calcium channel blockers viz. verapamil, diltiazem and nifedipine, and to examine their effect on β-adrenoceptor stimulation. It used the β-agonist isoprenaline (ISO) and the mixed [α₁/β]agonist noradrenaline (NA), for its combined [α₁/β]adrenoceptor stimulation, on agonist-induced increases in the production of radio-labelled aMT and N-acetylserotonin(aHT) -measured as the sum of N-acetylated product- from [¹⁴C] serotonin. This was done using organ cultures of rat pineal glands. It was speciously assumed that this drug paradigm would allow the determination of Ca²⁺ influx and/or the blocking thereof in the reported potentiation by using ISO as a non Ca²⁺ -entry stimulating agonist, compared with NA and its Ca²⁺ -entry stimulating properties. Surprisingly, all 3 CCB's potentiated the effect of NA. Only diltiazem was found not to potentiate the effect of ISO. In an attempt to uncover the reason for these results, the study moved toward a mechanistic approach,focusing in an antecedent manner on the various steps in the indole metabolic pathway to identify the point at which the change occurred, and hence possibly elucidate the mechanism responsible for the paradoxical increase. Experiments which assayed the levels of NAT, under the same drug conditions, showed the paradoxical increase to be already evident at this stage. Secondary experiments confirmed that NA stimulation of the pineal is dependent on Ca²⁺, both in organ culture and with NAT: the Ca²⁺ chelator EGTA abolished adrenergically-induced stimulation, while Ca²⁺ added after EGTA, restored the enzyme activity. The ionophore A23187 (which is able to transport Ca²⁺ directly into the pinealocyte via a mechanism which differs from the α₁ - mechanism) when used in conjunction with ISO or NA, was able to potentiate the responses of these two agonists relative to control values (agonist-alone), but by itself had no effect. With the enzyme NAT critically dependent upon cAMP for its induction, it was decided to determine the levels of cAMP and then those of its regulator, cAMP-phosphodiesterase (cAMP-PDE). This reasoning was prompted by reports of anti-calmodulin activity shown by the CCBs, in addition to their channel blocking effects. By binding to calmodulin (CaM), the CCBs are reportedly able to inhibit the CaM-dependent activation of cAMP-PDE. Following NA stimulation, verapamil caused a significant decrease in cAMP-PDE levels and an increase in cAMP. The other CCBs showed a similar trend. Glands stimulated with ISO in the presence of verapamil and nifedipine showed no significant differences in cAMP or cAMP-PDE levels. Diltiazem, however, was found to decrease the effect of ISO on cAMP while causing a concomitant increase in cAMP-PDE. This i) supported a possible hypothesis that the observed enhancement is a result of cAMP levels remaining elevated due to an inhibition of cAMP-PDE by the CCEs and ii) pointed to the possible presence of a CaM-sensitive PDE within the rat pineal gland. To test this hypothesis, two drugs which are more specific in their actions on CaM effects were chosen to see if the earlier results could be mimicked and thereby confirmed. Glands stimulated with NA in the presence of the specific CaM inhibitor R 24571 showed increased NAT activity and [¹⁴C]-aMT production. cAMP-PDE levels were clearly down, thus corroborating the possibility of cAMP-PDE inhibition. Glands incubated in the presence of M&B 22948, a CaM-sensitive PDE inhibitor, showed similar increases in NAT activity and [¹⁴C]-aMT. These findings therefore support the initial results and although indirect, confirm the hypothesis that the paradoxical increase following predominantly NA stimulation could be a result of cAMP levels remaining elevated, due to inhibition by the CCEs of the CaM-dependent activation of its regulator cAMP-PDE. In summary, data presented herein concur with proposals that: i) the CCEs are not specific enough to be used as tools to research Ca²⁺ -mediated events, as they appear to have sites of action other than the voltage operated channel (VOC); eg. binding to calmodulin, ii) there are functional differences between the CCEs as shown by diltiazem in this series of experiments, iii) there is a CaM-sensitive-PDE present in the pineal.
26
Lomakina, Yu V. "Morphology of pineal gland in old rats under light deprivation and its correction." Thesis, БДМУ, 2017. http://dspace.bsmu.edu.ua:8080/xmlui/handle/123456789/16845.
27
Khan, Razeeya B. "A study of possible interactions between the pineal gland and the opioidergic system." Thesis, Rhodes University, 1990. http://hdl.handle.net/10962/d1001468.
Abstract:
Recent observations suggest a link between the pineal gland and the opioid system. Possible areas of interaction between the pineal gland and the opioidergic system in Wistar rats were investigated. The effect of opioids on the pineal gland in organ culture was monitored. Neither morphine, methadone nor the opioid antagonist naloxone was found to affect [¹⁴C]-serotonin metabolism by the pineal gland in vitro. Both the pineal gland and the opioid system are influenced by exposure to stressful stimuli. Morphine and melatonin had protective effects on stress-induced gastric lesions. The ability of melatonin to inhibit lesion formation was found not to be exerted via an opioidergic mechanism. Evidence has been obtained for a possible modulation of the stress response by the pineal gland . The opioid drugs are the most potent analgesic agents available. A possible interaction between the opioid system and the pineal gland in the modulation of the response to noxious stimuli was investigated. An intact pineal gland was found to be necessary for the manifestation of the nocturnally increased response of rats to noxious stimuli
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Ferreira, Danilo da Silva 1987. "Repercussão metabólica na prole adulta gerada à partir de mães com ausência de melatonina durante a gestação e lactação." [s.n.], 2012. http://repositorio.unicamp.br/jspui/handle/REPOSIP/309381.
Abstract:
Orientador: Gabriel Forato AnhêDissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Ciências Médicas
Made available in DSpace on 2018-08-21T21:51:55Z (GMT). No. of bitstreams: 1 Ferreira_DanilodaSilva_M.pdf: 1985537 bytes, checksum: f5ffd05c3c43f82bc05681d53ad9c12c (MD5) Previous issue date: 2012
Resumo: É sabido que a exposição de ratas gestantes a retardos no início da fase clara diminui a secreção de melatonina, gerando intolerância à glicose na prole. No rato adulto, a melatonina exerce controle sobre aspectos circadianos do metabolismo. Esse controle ocorre por modulação da produção de insulina e supressão da gliconeogênese noturna. O presente trabalho busca analisar a importância da melatonina materna na programação metabólica da prole. Descobrimos que a prole originada de mães pinealeactomizadas (PINX-P1) desenvolveu resistência hepática à insulina com aumento de enzimas gliconeogênicas. Não houve alterações na sinalização da insulina na musculatura esquelética. As ilhotas isoladas do grupo PINX-P1 apresentaram uma diminuição na secreção de insulina frente ao estímulo com glicose. É importante ressaltar que os achados metabólicos ocorreram no final da fase clara, do ciclo claro/escuro, indicando que o grupo PINX-P1 apresentava uma intolerância à glicose tempo-dependente. O perfil metabólico da prole não sofreu alteração em mães pinealectomizadas que receberam reposição de melatonina durante a gestação e lactação Assim, os presentes achados apóiam a hipótese de que a melatonina materna durante a gestação é responsável pela programação metabólica da prole
Abstract: Phase shifts are known to decrease night time melatonin secretion and to elicit glucose intolerance in the offspring when applied to gestating rats. In the adult rat, melatonin plays an important role in the circadian control of metabolism by timing insulin action and suppressing nocturnal gluconeogenesis. The present study addresses, therefore, the importance of maternal melatonin for the programming of the metabolic status of the offspring. We found that rats born to and breast-fed by pinealectomized mothers (PINX-P1) were glucose intolerant displaying hepatic insulin resistance and increased gluconeogenesis. No parallel changes in insulin signal transmission were detected in skeletal muscle. Pancreatic islets isolated from PINX-P1 presented impaired glucose-stimulated insulin secretion. Importantly, these alterations were detected exclusively at the end of the light phase of the light/dark cycle, indicating that PINX-P1 rats exhibit time-dependent glucose intolerance. This altered pattern of daily energy metabolism was absent in the offspring of pinealectomized mothers that received melatonin replacement during pregnancy and lactation. The present results support the novel concept that maternal melatonin is responsible for the programming of the daily pattern of energy metabolism in the offspring
Mestrado
Farmacologia
Mestre em Farmacologia
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Barros, Roseâmely Angélica de Carvalho. "Anatomia macroscópica e microscópica da glândula pineal do macaco Cebus apella." Universidade de São Paulo, 2006. http://www.teses.usp.br/teses/disponiveis/10/10132/tde-18122006-125619/.
Abstract:
O objetivo deste estudo é descrever a organização anatômica da glândula pineal do macaco Cebus apella, analisando seus aspectos macroscópicos e microscópicos, vistos sob a óptica da microscopia de luz, microscopia eletrônica de transmissão e microanálise por difração de RX. Para desenvolver este trabalho utilizamos 12 exemplares de macaco Cebus apella, cedidos pelo IBAMA ? MG. Para a análise macroscópica utilizamos 12 animais, os quais foram empregados para estudos relacionados à topografia e sintopia do corpo pineal. Desse grupo, 07 espécimes foram utilizados para a microscopia de luz, 01 espécime para microscopia eletrônica de transmissão e 01 espécime para microscopia eletrônica de varredura, preparados conforme técnicas histológicas de rotina. A glândula pineal do macaco Cebus apella apresentou-se como um pequeno órgão de forma e dimensões variáveis, medindo de 2,5 mm a 4,0 mm de comprimento e de 2,0 mm a 3,5 mm de largura. Está localizada caudalmente ao esplênio do corpo caloso, em correspondência ao recesso pineal, podendo ser classificada como subcalosa e do tipo A, segundo Vollrath (1981). É revestida externamente por uma cápsula de tecido conjuntivo, rica em fibras colágenas, derivada da pia-máter. No parênquima glandular verificam-se três tipos de células: pinealócitos, células da glia e mastócitos. De acordo com as características morfológicas dos núcleos, identificamos pinealócitos do tipo I e pinealócitos do tipo II. Concreções arredondadas e em forma de mórula são vistas no parênquima glandular, nas quais a microanálise por difração de RX demonstrou dois componentes principais: o fósforo e o alumínioThe objective of this study is to describe the anatomical organization of the pineal gland of the Cebus apella monkey, analyzing its macrocospic and microscopical aspects, seen under the optics of the light microscopy, electronic microscopy of transmission and microanalysis by emission of X-Ray. In the development of this study 12 units of Cebus apella monkey, supplied by IBAMA ? MG, were used. For the macrocospic analysis we used 12 animals, which had been used for topography and related to pineal body related studies. From this group, seven specimens were used on the light microscopy, one specimen on electronic microscopy of transmission and one specimen on electronic microscopy of scanning. All the specimens were prepared according to histological techniques of routine. The pineal gland of the Cebus apella monkey presented itself as a small organ of variable forms and lengths, measuring 2,5mm to 4,0mm in length and 2,0mm to 3,5mm in width. It is caudally located to the esplenium of the calosus body, in relation to the pineal recess, being classified as subcalosus and type A according to Vollrath (1981). It is externally covered by a conjunctive tissue capsule, rich in collagen fibers, derived from the piamater. In the glandular parenchyma three types of cells are verified: pinealocytes, cells of the glia and mast cells. According to the morphologic characteristics of the cores, we identify pinealocytes of type I and pinealocytes of type II. Corpora arenaceae round and in morula shape are seen in the glandular parenchyma in which the microanalysis by emission of X-Ray showed two main components: the phosphorus and the aluminum
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Resende, Henrique Ribeiro Alves de. "Avaliação morfo-quantitativa da glândula pineal de éguas em atividade reprodutiva e em anestro fisiológico." Universidade de São Paulo, 2006. http://www.teses.usp.br/teses/disponiveis/10/10132/tde-04042007-140604/.
Abstract:
A glândula pineal (GP) integra o epitálamo, mostra-se sensível à luz e secreta um hormônio, a melatonina. Em vertebrados sua secreção é estimulada na ausência de luminosidade e parece interferir na adaptação das funções reprodutivas às condições de luminosidade, especialmente em animais que se reproduzem sazonalmente, possibilitando o nascimento dos filhotes em época mais favorável. Considerando a importância econômica dos eqüinos, tais particularidades tornam-se alvo de pesquisas, justificadas pela ação da GP sobre a reprodução. Objetivou-se avaliar aspectos macro e microscópicos do órgão, como características qualitativas referentes a fibras colágenas (FC) e elásticas (FE); número (NP) e tamanho (PP) de pinealócitos (Pnlct), e eventuais correlações entre estas e os períodos reprodutivos. Para tanto, utilizaram-se 24 éguas, selecionadas por palpação retal e idade, e distribuídas em duas fases: atividade reprodutiva (AR) e anestro fisiológico (AF), cada uma com 2 grupos (3-8 e 15-20 anos). Os animais foram medidos à cernelha (H) e pesados (PV). Colheu-se amostra de sangue para dosagem de estrógeno (E2), progesterona (P4) e melatonina (Mlt), bem como procedeu-se à retirada do sistema genital (SG) para comprovação da fase reprodutiva; do encéfalo e GP para mensurações, e desta para análises histológicas. Nos espécimes, além da avaliação visual do SG, foram determinados o comprimento (CE) e largura (LE) dos encéfalos; o comprimento (CO), largura (LO) e altura (AO) dos ovários e das GP (CGP, LGP e AGP). Após documentação fotográfica as GP foram seccionadas em seu maior eixo, obtendo-se 4 quadrantes. Adotou-se esquema de rodízio para imersão destes em soluções de Bouin, glutaraldeído, Metacar e McDowell. Utilizaram-se colorações por hematoxilina-eosina, fucsina básica/azul de toluidina, Verhöeff e técnica específica para microscopia eletrônica de transmissão. Para estudo morfométrico foi determinado o perímetro de 480 Pnlct por animal e avaliado o número destes em 2,48 mm² de tecido glandular. Os dados foram analisados utilizando-se estatística descritiva, correlação de Pearson, teste "F" e de Scott-Knott. A GP localizou-se no plano sagital mediano, dorso-caudalmente à aderência inter-talâmica e ventralmente ao esplênio do corpo caloso, apresentando formato ovóide ou piriforme (tipo A ou sub-calosa). Está envolvida por cápsula de tecido conjuntivo (TC), da qual partem septos que, acompanhados por vasos sanguíneos, dividem o parênquima em lóbulos. Os principais componentes glandulares são Pnlct e astrócitos. O PV, H, concentrações de E2, Mlt, CE, LE, CGP, LGP, AGP e PP não diferiram entre idades e/ou fases. Não foram encontradas interações entre PV, H, tamanhos de ovários, encéfalo e GP. Concentrações de P4 foram maiores nos animais em AR. O NP foi maior naqueles em AF, em ambas idades. Observaram-se FE em éguas em AR e AF, mas em maior quantidade nas jovens. Naquelas em AR observou-se maior quantidade de TC e de FC do tipo I. Nas em AF foi maior a quantidade de FC do tipo III e de Pnlct. Fibras nervosas e vesículas granulares e agranulares foram identificadas tanto no citoplasma de Pnlct quanto fora dele. Concreções calcáreas foram evidenciadas no núcleo, citoplasma ou espaço extracelular de todas GPs, independentemente da idade e/ou fase reprodutiva.The pineal gland (PG) is part of the epithalamus, is sensitive to light and secretes the hormone melatonin. In vertebrates its secretion is stimulated by lack of luminosity and appears to interfere with reproductive functions adaptation to luminosity, especially in seasonal breeding animals, directing births to periods more favorable for offspring survival. Considering the equine industry economical importance, research targets, focused on PG action in reproduction becomes very relevant. The objective was to evaluate macro and microscopic aspects of the PG, qualitative characteristics pertaining to collagen (CF) and elastic (EF) fibers; pinealocyte (Pnlct) number (PN) and size (PS) and eventual correlations between these variables and distinct reproductive periods. Twenty four mares were selected by rectal palpation and age, and classified as physiologically anestrous (PA) or reproductively active (RA). Furthermore, within PA and RA mares, two age subgroups (3 - 8 and 15 - 20 years old) were formed. Whither height (WH) and body weight (BW) were also recorded. Blood samples were taken for estradiol (E2), progesterone (P4) and melatonin (Mlt) measurements, as well as collection of the reproductive tract (RT), of the encephalon and PG for gross measurements and histological analysis. Macroscopic evaluation of the RT, length (EL) and width (EW) of the encephalon were determined. Ovary and PG lengths, widths and heights (OL and PGL, OW and PGW, and OH and PGH, respectively) were also measured. After photographic documentation PGs were sectioned along their major axis resulting in four quadrants. A rotational scheme was adopted for PG tissue immersion in Bouin´s, glutaraldehyde, metacar and McDowell solutions. The following staining procedures were used: haematoxylin-eosin, basic fuchsin/toluidine blue, Verhöeff and a transmission electron microscopy specific technique. For the morphometric study, the diameter of 480 Pnlct per animal was determined. PN was determined in 2.48mm² of PG tissue. Data was analysed by descriptive statistics, Pearson´s correlation and F and Scott-knott tests were performed for mean comparisons. PG was located in the median sagital plane, dorsocaudally to the inter-thalamic adherence and ventrally to the corpus callosum esplenium, showing an ovoid or piriform (type A or sub-callosum). The PG is surrounded by connective tissue (CT), from which septa originate, followed by blood vessels that divide the parenchyma in lobules. The main glandular components are Plnct and astrocytes. Body weight, WH, E2, Mlt, EL, EW, PGL, PGW, PGH and PS did not differ between age group and reproductive status. No interactions between BW, WH, ovarian, encephalon and PG sizes were observed. Progesterone concentrations were higher in RA mares. Pinealocyte number was greater for RA mares from either age group. EF content was similar between RA and PA mares, but higher in the younger groups. Higher CT and type I CF were observed in RA mares. Higher type III CF and PN were found in FA mares. Nervous fibers and granular and agranular vesicles were identified either in the Plnct cytoplasm or in the extra-cellular space. Calcium concretions were observed in the nucleus, cytoplasm or extra-cellular space of all PGs, independently of age and/or reproductive status.
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Ashton, Anna. "Diurnal signalling of the vitamin A metabolite, retinoic acid, and its role in the mammalian pineal gland." Thesis, University of Aberdeen, 2018. http://digitool.abdn.ac.uk:80/webclient/DeliveryManager?pid=237657.
Abstract:
Vitamin A is an essential dietary component which primarily acts through its active metabolite, retinoic acid (RA), a potent transcriptional regulator that also has non-genomic activities. There is increasing evidence for a role for vitamin A in the regulation of circadian rhythms, and previous studies suggest that it serves important roles in the pineal gland, an integral component of the circadian system due to its function of melatonin production. However very little is currently known about how these effects are mediated, or about RA signalling in the pineal gland. This study aimed to establish whether RA is synthesised in the rat pineal gland and determine its role here. This included investigating whether RA is subject to diurnal changes in synthesis and signalling, and examining its involvement in the key rhythms in this gland: melatonin synthesis, kinase activation and clock gene expression. Organotypic culture of rat pineal glands, qPCR and western blotting were among the techniques employed to do this, as well as RA quantification using a reporter cell line. The rat pineal gland was found to produce RA and robust diurnal changes in synthesis were detected. Furthermore, diurnal changes in expression of RA signalling genes suggested there are corresponding changes in RA activity. RA was not found to rapidly regulate Aanat transcription, melatonin synthesis or clock gene expression in vitro, however it was found to rapidly down-regulate extracellular signal-regulated kinase (ERK) 1/2 phosphorylation. Furthermore, strong cytoplasmic expression of RA receptor α was detected in pinealocytes. These results suggest RA has a non-genomic role in the pineal gland and may be involved in driving the diurnal rhythm in kinase activation.
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Cecon, Erika. "Sistema melatonérgico como alvo do peptídeo β-amiloide." Universidade de São Paulo, 2014. http://www.teses.usp.br/teses/disponiveis/41/41135/tde-29092014-083625/.
Abstract:
A doença de Alzheimer (AD) é a doença neurodegenerativa relacionada ao envelhecimento mais frequente no mundo. Uma das características moleculares de AD é a produção exacerbada de peptídeos beta-amiloide (Aβ), principalmente dos fragmentos de 40 e 42 aminoácidos (Aβ1-40 e Aβ1-42). Aβ induz respostas neuroinflamatórias e alterações moleculares relacionadas à perda sináptica e morte neuronal. Diversos relatos mostram que pacientes de AD apresentam redução na concentração plasmática de melatonina, hormônio produzido pela glândula pineal e também alteração na expressão dos receptores de melatonina, mas os mecanismos envolvidos ainda não são conhecidos. De acordo com o conceito do eixo imunepineal, agentes inflamatórios são capazes de atuar diretamente sobre a glândula pineal e inibir a síntese de melatonina. No presente estudo investigamos, portanto, se o peptídeo Aβ atua diretamente sobre o sistema melatonérgico, modulando a síntese de melatonina ou a função de seus receptores. Pineais em cultura tratadas com Aβ 1-40 ou Aβ 1-42 apresentaram redução na produção de melatonina. Aβ 1-40 ativou a via do fator de transcrição NF-κB na pineal, resultando em aumento da transcrição de diversos genes inflamatórios, como interleucinas e quimiocinas, e inibição da expressão da enzima arilalquilamina N-acetiltransferase, essencial à síntese de melatonina. Em células HEK293 expressando estavelmente receptores MT1 ou MT2 recombinantes, a ativação da via ERK1/2 pela melatonina foi inibida tanto por Aβ 1-40 quanto por Aβ 1-42. O mesmo efeito inibitório foi observado em células endoteliais primárias que expressam MT1 e MT2 constitutivamente. O presente trabalho mostra que a síntese de melatonina pela pineal e a função dos receptores de melatonina são diretamente regulados por Aβ, o que amplia nossos conhecimentos a respeito dos efeitos prejudiciais de Aβ. Considerando que a melatonina tem propriedades neuroprotetora e antioxidante, a disfunção do sistema melatonérgico pode contribuir para os processos neurodegenerativos que ocorrem na patologia de ADAlzheimer\'s disease (AD) is the most common age-related neurodegenerative disorder worldwide. Excess of amyloid beta peptides (Aβ), composed mainly by 40 and 42 aminoacids-long fragments (Aβ 1-40 e Aβ 1-42) is a molecular hallmark in AD. Aβ-induced neuroinflammatory responses and molecular changes are related to synapse impairment and neuronal loss. It is well documented that AD patients show impaired melatonin synthesis, the pineal gland-derived hormone, and altered expression of melatonin receptors, but the underlying mechanisms remain unclear. According to the immune-pineal axis concept, inflammatory mediators act on the pineal gland, leading to inhibition of melatonin synthesis. Therefore, in the present study we sought to investigate whether Aβ? directly targets the melatonergic system, modulating melatonin synthesis and/or melatonin receptors function. Pineal glands cultured in the presence of Aβ 1-40 or Aβ 1-42 showed reduced melatonin production. Aβ 1-40 activated the nuclear factor kappa B (NF-κ B) pathway in the pineal gland, leading to up-regulation of several inflammatory genes, as interleukins and chemokines, and inhibition of the arylalkylamine N-acetyltransferase enzyme expression, the key enzyme in melatonin synthesis. In HEK293 cells stably expressing recombinant melatonin MT1 or MT2 receptors melatonin-induced ERK1/2 activation was markedly impaired by Aβ 1-40 and Aβ 1-42. Similar results were obtained in primary culture of endothelial cells expressing melatonin receptors endogenously. The present study shows that melatonin synthesis and melatonin receptors function are directly impaired by Aβ, thus extending our understanding on the detrimental effects of Aβ. Because melatonin shows neuroprotective and antioxidant properties, impairment of the melatonergic system may contribute to the neurodegenerative processes that take place in AD. 1-42) is a molecular hallmark in AD. Aβ-induced neuroinflammatory responses and molecular changes are related to synapse impairment and neuronal loss. It is well documented that AD patients show impaired melatonin synthesis, the pineal gland-derived hormone, and altered expression of melatonin receptors, but the underlying mechanisms remain unclear. According to the immune-pineal axis concept, inflammatory mediators act on the pineal gland, leading to inhibition of melatonin synthesis. Therefore, in the present study we sought to investigate whether Aβ?directly targets the melatonergic system, modulating melatonin synthesis and/or melatonin receptors function. Pineal glands cultured in the presence of Aβ 1-40 or Aβ 1-42 showed reduced melatonin production. Aβ 1-40 activated the nuclear factor kappa B (NF-&kappa B) pathway in the pineal gland, leading to up-regulation of several inflammatory genes, as interleukins and chemokines, and inhibition of the arylalkylamine N-acetyltransferase enzyme expression, the key enzyme in melatonin synthesis. In HEK293 cells stably expressing recombinant melatonin MT1 or MT2 receptors melatonin-induced ERK1/2 activation was markedly impaired by Aβ 1-40 and Aβ 1-42. Similar results were obtained in primary culture of endothelial cells expressing melatonin receptors endogenously. The present study shows that melatonin synthesis and melatonin receptors function are directly impaired by Aβ, thus extending our understanding on the detrimental effects of Aβ. Because melatonin shows neuroprotective and antioxidant properties, impairment of the melatonergic system may contribute to the neurodegenerative processes that take place in AD
33
McAllan, B. M. "The regulation of seasonal reproductive cycles in "Antechinus" : photoperiodic and pineal correlates /." Title page, contents and abstract only, 1987. http://web4.library.adelaide.edu.au/theses/09SM/09smm114.pdf.
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Burns, Danny Michael. "Pineal-mediated inhibition of prolactin cell activity: Investigation of dopaminergic involvement." Diss., The University of Arizona, 1989. http://hdl.handle.net/10150/184696.
Abstract:
The purpose of these studies was to determine whether the inhibitory effects of short photoperiod exposure on prolactin cell activity in male Syrian hamsters and/or the inhibitory effects of melatonin treatment on the growth and activity of diethylstilbestrol- (DES) induced prolactinomas in Fisher 344 (F344) rats were possibly mediated through alterations in dopaminergic regulatory mechanisms. In both the hamster and the rat, changes in hypothalamic dopamine neuronal activity and changes in pituitary responsiveness to dopamine have been suggested as possible mechanisms in the prolactin-inhibitory effects of light deprivation or melatonin administration. The present studies in the male Syrian hamster addressed two issues. First, it was of interest to determine if anterior pituitaries of long photoperiod-exposed male hamsters possess dopamine receptors, which are presumably necessary for responsiveness to dopamine. This was accomplished by analysis of ³H-spiperone binding to anterior pituitary membranes. Second, possible changes in pituitary sensitivity to dopamine were assessed by comparison of dose response curves for the inhibition by dopamine of prolactin release from hemipituitaries incubated in vitro from both long and short photoperiod-exposed animals over a series of time points from three to fifteen weeks. In the second series of experiments, adult female F344 rats received daily injection of melatonin or saline vehicle. After two weeks, half of the animals were sacrificed for analysis of ³H-spiperone binding to anterior pituitary membranes, measurement of hypothalamic dopamine turnover and analysis of in vitro pituitary sensitivity to dopamine. The remaining animals received subcutaneous implants containing DES and injections were continued on the same schedule until sacrifice four weeks later for measurement of the same parameters. In both the hamster and rat models, treatments exerted profound inhibitory effects on indices of prolactin cell activity. However, these studies provide no evidence for the involvement of altered dopaminergic regulation in the production of such effects. Neither pituitary sensitivity to dopamine in vitro nor hypothalamic dopamine neuronal activity was enhanced by short photoperiod exposure or melatonin treatment. Prolactin-inhibitory effects of these treatments appear to be mediated through as yet unidentified dopamine-independent mechanisms.
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Teodoro, Luis Henrique de Souza. "Caracterização funcional do receptor P2X7 na glândula pineal de rato." Universidade de São Paulo, 2013. http://www.teses.usp.br/teses/disponiveis/41/41135/tde-28032014-093312/.
Abstract:
A sinalização purinérgica tem sido demonstrada como um um importante modulador dediversos processos fisiológicos e fisiopatológicos. Dentre os receptores purinérgicos, o receptor P2X7 distingui-se por requerir altas concentrações de ATP em sua ativação. As demonstrações prévias de que a glândula pineal responde a diferentes estímulos purinérgicose a altas concentrações de ATP sugere um papel para os receptores P2X7 nesta glândula, embora sua expressão e função não estivesse estabelecida. O objetivo deste trabalho, portanto, foi caracterizar funcionalmente o receptor P2X7 na glândula pineal de ratos. Os resultados obtidos demonstram, pela primeira vez, a expressão gênica e proteica do receptor P2X7 na glândula pineal. Os efeitos da ativação destes receptores levam a uma inibição nos níveis de melatonina induzida por isoprenalina por um mecanismo independente da via do fator de transcrição NF-kB e da fosfolipase C. Além disso, a estimulação destes receptores inibiu a síntese de TNF induzida por LPS, resultado este semelhante ao observado na presença do pré-tratamento com antagonistas do receptor P2X7. Estes dados confirmam a presença de receptores P2X7 na glândula pineal e reiteram o relevante papel da estimulação purinérgica a sobre a síntese de melatonina e sobre a capacidade da pineal em responder a PAMPs, como o LPSPurinergic signalling has been demonstrated as an important modulator ofseveral physiological and pathophysiological processes. Among the purinergic receptors, the activation of P2X7 receptor requireshigh concentrations of ATP. The previous demonstration that the pineal gland is responsive to different purinergic stimulus and to high concentrations of ATPsuggests a role for P2X7, although its expression and function remained unclear. The aim of this study was to functionally characterize the P2X7 receptor in the rat pineal gland.The data showedthe P2X7 receptor mRNA and protein expression in the pineal gland. The effect of its activation leads toan inhibition of melatonin content induced by isoprenaline through an independent NF-kB and PLC pathways. Furthermore, the P2X7 receptor activation inhibits the LPS-induced TNF synthesis, a similar result observed in the presence of the pre-treatment with P2X7 receptors antagonists. These data demonstrate the presence of P2X7 receptors in the rat pineal gland and confirm the relevant role of the purinergic stimulation to the pineal melatonin synthesis and responsiveness to PAMPs such as LPS
36
Shchudrova, T. S. "Renoprotective effect of melatonin in conditions of acute kidney injury and altered pineal gland activity." Thesis, БДМУ, 2020. http://dspace.bsmu.edu.ua:8080/xmlui/handle/123456789/18250.
37
Peres, Rafael. "Influência da ingestão de álcool na produção de melatonina pineal e suas consequências sobre a expressão dos receptores de melatonina e dos genes relógio no Sistema Nervoso Central." Universidade de São Paulo, 2009. http://www.teses.usp.br/teses/disponiveis/42/42137/tde-01072009-115136/.
Abstract:
Já foi demonstrado que o consumo de álcool induz complicações no início do sono e na sua manutenção, mas sua influência na produção de melatonina não é clara. O presente trabalho mostra que ratos machos ingerindo uma solução de etanol 10% apresentam uma curva de produção de melatonina alterada, com menor produção média na noite. Isto pode ser parcialmente explicado por uma redução observada na atividade da enzima TPH e especialmente da AANAT. Também verificamos que a expressão dos genes para ambas enzimas se encontra diminuída. Os resultados mostram um impacto do álcool no início da sinalização da produção de melatonina, com alteração na expressão dos receptores de noradrenalina. Também foi observado que o tratamento modifica o padrão de expressão dos receptores de melatonina MT1 e MT2 no hipocampo, no cerebelo e no núcleo supraquiasmático. Nesta última estrutura também verificamos alterações na expressão dos genes relógio. Estas alterações em conjunto poderiam ocasionar os problemas de memória, aprendizado e sincronização circadiana descritas para pacientes alcoólatras.It has been demonstrated that alcohol consumption induces complications in sleep onset and maintenance but its influence on melatonin production remains unclear. The present results show that rats receiving 10% ethanol in drinking water for 35 days display an altered melatonin daily profile, with a reduction in the nocturnal mean. This can be partially explained by the reduction in TPH and mainly in AANAT activity. In addition, mRNA expression of both enzymes was also decreased. Upstream in melatonin synthesis pathway, the results showed that noradrenergic signaling is impaired as well. Together, these results state the reasons for the observed melatonin synthesis reduction. Our results also show that alcohol intake causes an alteration in the expression of melatonin receptors MT1 and MT2 in hippocampus, cerebellum and suprachiasmatic nucleus. We have also observed an alteration in the expression of clock genes in the suprachiasmatic nucleus. These alterations are possibly causing problems to the learning, memory process and circadian synchronization.
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Matos, Raphael Afonso de. "Efeitos da melatonina pineal sobre a neurogênese de ratos submetidos ao treinamento físico aeróbio." Universidade de São Paulo, 2014. http://www.teses.usp.br/teses/disponiveis/42/42137/tde-11032015-183414/.
Abstract:
Melatonina é um hormônio produzido principalmente pela pineal, possui caráter temporizador do meio interno, ação antioxidante, neuroprotetora e neurotrófica. Outro fator que age nos processos de neuroplasticidade é o exercício físico. Este é responsável por alterar parâmetros metabólicos nos animais, e trabalhos do nosso grupo demonstraram que tais adaptações metabólicas em ratos dependem da melatonina pineal. Diante disso investigamos se as adaptações neuroplásticas em ratos submetidos ao treinamento físico também estariam relacionadas à presença deste neuro-hormônio. Nossos resultados demonstram que a melatonina não influenciou a expressão gênica e quantificação proteica de indicadores da neurogênese, somente a realização do treinamento físico alterou alguns dos parâmetros avaliados. Os níveis de corticosterona se mostraram alterados nos animais pinealectomizados. A avaliação da expressão gênica circadiana com oito pontos ao longo das 24 horas revelou o comportamento variável do mRNA de algumas proteínas atreladas ao processo de plasticidade hipocampalMelatonin is a hormone produced mainly by pineal gland, has timer character of the internal medium, antioxidant action, neuroprotective and neurotrophic. Another factor that acts in the processes of neuroplasticity is physical exercise. This is liable to change metabolic parameters in animals, and work by our group have shown that such metabolic adaptations in rats depend on pineal melatonin. Thus we investigated whether the neuroplastic adaptations in rats submitted to physical training also would be related to the presence of this neurohormone. Our results demonstrate that the melatonin did not influence the gene expression and protein quantification of indicators of neurogenesis, only the execution of the physical training has changed some of the parameters evaluated. The levels of corticosterone were changed in pinealectomized animals. The assessment of gene expression circadian with eight points along the 24 hours showed the variable behavior of the mRNA of some proteins linked to the process of hippocampal plasticity.
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Peres, Rafael. "Estudo da presença, da função e das vias de produção da melatonina em invertebrados." Universidade de São Paulo, 2013. http://www.teses.usp.br/teses/disponiveis/42/42137/tde-20092013-095552/.
Abstract:
O tecido adiposo, através da leptina, desempenha um papel permissivo sobre a maturação sexual do indivíduo. Apesar da importância do tecido adiposo para a puberdade, pouco se sabe a respeito do processo de formação deste tecido neste período da vida. Estudos em humanos têm descrito a presença de resistência à insulina puberal. Assim, frente à importância do tecido adiposo para a puberdade, o objetivo do trabalho foi investigar a resposta do tecido adiposo à insulina no período puberal. Foram utilizados os coxins adiposos subcutâneo e periepididimal. Na puberdade, paralelamente à intolerância à glicose transitória que ocorreu nas semanas iniciais, e, portanto, prejuízo da utilização da glicose pelos tecidos insulino-dependentes, o tecido adiposo (SC e PE) teve sua responsividade normal à insulina e uma melhor capacidade de incorporação de glicose em lipídeos o que leva a crer que há um desvio da utilização deste substrato energético, a glicose, para a formação do tecido adiposo.The adipose tissue is critical to puberty. Leptin exerts a permissive role to hypothalamic-hypophysial-gonadal maturation and, thereby, adipose tissue is necessary to pubertal development. Despite its importance to puberty, little is known about the process of adipose tissue formation during this period of life. Researches have described insulin resistance at pubertal period in humans. The adipose tissue importance to puberty added to pubertal insulin resistance described in humans lead us to investigate how the adipose tissue responds to insulin at this period since it is essential at this time. We assessed two distinct fat pads: the subcutaneous fat pad and the epididymal one. At the puberty, despite the temporary glucose intolerance and the constraint for glucose utilization by insulin-dependent tissues, the adipose tissue had normal insulin responsiveness plus an improved capacity to synthesize lipids from glucose which led us to hypothesize that glucose could have been deviated towards the adipose tissue.
40
Allen, Andrée Elizabeth. "Indole rhythms, locomotor activity and the environment /." [Hong Kong] : University of Hong Kong, 1988. http://sunzi.lib.hku.hk/hkuto/record.jsp?B12428619.
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Ornelas, Flavia Gomes Illa. "Caracterização de ecto-nucleotidases na glândula pineal de ratos." Universidade de São Paulo, 2013. http://www.teses.usp.br/teses/disponiveis/42/42136/tde-16062014-105416/.
Abstract:
A glândula pineal é um órgão neuroendócrino regulado pelo fotoperíodo ambiental. Sua principal inervação é constituída por fibras simpáticas provenientes do gânglio cervical superior que, liberando noradrenalina, ativa receptores b1 adrenérgicos resultando na produção noturna de melatonina, cuja biossíntese envolve a conversão da serotonina à NAS. O ATP, co-liberado com a noradrenalina, liga-se a receptores purinérgicos presentes na pineal e leva a uma potenciação da produção de NAS. Após a liberação, o ATP sofre rápida degradação enzimática, degradação esta, funcionalmente importante, uma vez que metabólitos do ATP atuam como ligantes em diferentes receptores. Os receptores purinérgicos são classificados em duas grandes famílias: receptores P1, que reconhecem adenosina e, receptores P2, que reconhecem principalmente ATP, ADP e AMP. Várias famílias de enzimas estão envolvidas na hidrólise de ATP liberado para o meio extracelular, sendo elas: as E-NTPDases, as E-NPPs e a ecto-5\'-nucleotidase. O presente trabalho teve como objetivo caracterizar a expressão gênica, a distribuição celular e a atividade das ecto-nucleotidases na glândula pineal de ratos a fim de aprimorar a caracterização do sistema purinérgico neste órgão.The pineal gland is a neuroendocrine organ regulated by environmental photoperiod. Its main innervation is constitute by fibers from the sympathetic superior cervical ganglion that by releasing noradrenaline active b1 adrenergic receptors resulting in the nocturnal production of melatonin whose biosynthesis involves the conversion of serotonin to NAS. ATP, co-released with norepinephrine binds purinergic receptors present in the pineal gland and leads to an enhancement of the production of NAS. After release, ATP and other nucleotides are rapid enzymatic degradation, this degradation is functionally important since ATP metabolites act as ligands in different receivers. Purinergic receptors are classified into two large families: P1 receptors that recognize adenosine and P2 receptors that recognize mainly ATP, ADP and AMP. Several families of enzymes are involved in the hydrolysis of ATP released into the extracellular environment: the E-NTPDase, E-NPP and the ecto-5\'-nucleotidase. This study aimed to characterize the gene expression, the cellular distribution and activity of ecto-nucleotidases in the rat pineal gland in order to improve the characterization of the purinergic system in this organ.
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Moraes, Renato Couto. "Papel da corticosterona na vigência do estresse sobre a função pineal em ratos." Universidade de São Paulo, 2010. http://www.teses.usp.br/teses/disponiveis/42/42136/tde-18102010-153227/.
Abstract:
O objetivo geral da presente tese é testar a hipótese que a pineal faz parte integrante da resposta ao estresse, da mesma forma que está integrada ao processo inflamatório. Dois modelos de estresse, contenção e frio, foram aplicados aos ratos por 30 min ou 2 horas. Os resultados foram: ausência de úlceras gástricas e TNF em nível sérico por ambos os estresses, apenas aumento de corticosterona; somente em duas horas qualquer um dos estresses aumentou significativamente melatonina da pineal; tratamento tanto com metirapona como com mifepristone aboliram indistintamente os efeitos dos estresses; tratamento tanto com talidomida como com fenilefrina não modificaram os efeitos dos estresses. Concluímos que, o estresse moderado agudo, pela ação da corticosterona, promove modulação da pineal na dependência do estado fisiológico da mesma. Confirmamos a existência de uma relação entre as glândulas adrenais e pineal. Afirmamos que a glândula pineal exerce, além de suas clássicas funções cronobióticas, um papel de grande sensor do estado geral ao organismo inteiro.The objective of this thesis is to test the hypothesis that the pineal is a player on stress response, likewise that it is one player in inflammatory process. Two stress models, restraint and cold, were applied to the rats for 30 min or 2 hous. The results were: absence of gastric ulcers and TNF serum levels in both stresses, just enhancement of corticosterone plasma levels; only in two hours anyone stress increased significantly pineal melatonin; metyrapone or mifepristone treatment abolish indistinctly the effects of the stresses; thalidomide or phenylephrine treatment did not modify the effects of the stresses. We conclude that the acute moderate stress by the corticosterone action promote modulation of pineal on the dependence of the physiological status of itself. We confirm the existence of a network between the adrenal and pineal glands. We affirm that the pineal gland performs, beyond of its chronobiotical classical functions, one role of the great sensor of internal body state to the whole organism.
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Taneda, Marco. "Papel da melatonina na regulação da ritmicidade circadiana de tecidos periféricos envolvidos com o metabolismo energético: avaliação do perfil diário da expressão dos genes relógio (clock genes)." Universidade de São Paulo, 2011. http://www.teses.usp.br/teses/disponiveis/42/42137/tde-23012012-152627/.
Abstract:
O metabolismo energético é dependente, dentre outros fatores, de uma temporização circadiana entre os tecidos participantes da regulação metabólica. O processo de sincronização parece depender da expressão dos genes relógio e de mediadores como a melatonina, que associam o oscilador central e os osciladores periféricos. Investigamos o papel da melatonina na expressão dos genes relógio em tecidos periféricos, onde ratos Wistar foram divididos em dois grupos: pinealectomizados e controle. Após 45 dias os animais foram sacrificados circadianamente e seus tecidos de interesse extraídos para análise através do PCR convencional. A pinealectomia ocasionou significativa desorganização temporal na expressão de quase todos os genes relógios dos tecidos muscular e do adiposo periepididimal. O tecido hepático foi o que menos sofreu alterações pela pinealectomia. Em conclusão, esses dados mostram que a melatonina é necessária para manutenção da ritmicidade dos genes relógio no tecido muscular estriado esquelético, no tecido adiposo periepididimal e no tecido hepático.The energy metabolism is dependent, between other factors, of a circadian timing among the tissues participants of the metabolic regulation. The synchronization process appears to depend on the expression of clock genes and mediators such as melatonin, involving the central oscillator and peripheral oscillators. We have investigated the role of melatonin in the expression of clock genes in peripheral tissues. Rats have been divided into two groups: pinealectomized and control rats. After 45 days the animals were sacrificed and their tissues of interest have been extracted for analysis by conventional PCR. Pinealectomy caused a significant disruption in the temporal expression of almost all genes of muscle tissue and fat tissue. The liver tissue was the least affected by changes of pinealectomy. In conclusion, these data show that melatonin is necessary for maintaining the rhythmicity of clock genes in skeletal muscle, adipose tissue and liver tissue.
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HILL, STEVEN MARC. "THE ANTIPROLIFERATIVE EFFECT OF THE PINEAL HORMONE, MELATONIN, ON HUMAN BREAST CANCER CELLS IN VITRO." Diss., The University of Arizona, 1986. http://hdl.handle.net/10150/183883.
Abstract:
There is some evidence to suggest that the pineal gland influences neoplastic growth. Either crude or partially purified pineal extracts have been used to treat malignant neoplasms in humans. More compelling evidence indicates that the pineal hormone melatonin, in addition to its well-known antireproductive effects, may also exert oncostatic effects particularly in animal models of human breast cancer. The purpose of this study was to examine a possible direct action of melatonin on the growth morphology and physiology of human breast cancer cells in vitro. Studies are described in which physiological concentrations of melatonin are shown to have markedly inhibitory effects directly on MCF-7 human breast cancer cells grown in culture. This antimitotic effect is not observed in MCF-7 cells at supra- or subphysiological concentrations of melatonin. This growth-inhibitory effect appears to be tissue specific since fibroblastic cells were not affected by melatonin. Other pineal indoles failed to inhibit the proliferation of this human breast cancer cell line, suggesting that this growth-inhibitory effect is specific for melatonin and is not a general characteristic shared among the family of pineal indoles. Reductions in media serum concentrations dramatically suppressed the response of cells to melatonin's inhibitory action. Serum values of 2.5 percent or lower resulted in a loss of melatonin's action as did growing the cells in serum-free medium or medium containing charcoal-treated serum. It appears that certain serum factors are necessary for these cells to respond to melatonin's antiproliferative action. Melatonin, when added to cells grown in media supplemented with 10 percent fetal calf serum decreased the synthesis of proteins and resulted in morphological alterations suggestive of a sublethal toxic injury. Melatonin appears to have a direct role in inhibiting the proliferation of breast cancer cells; however, the presence of melatonin per se does not seem to be the fundamental cause of this antimitotic action since no activity is observed when cells are propagated in media containing charcoal-treated fetal calf serum or serum-free medium. There appears to be a requirement for certain serum factors in this antiproliferative action. Two factors that have proved important in this process are the hormones estradiol and prolactin. (Abstract shortened with permission of author.)
45
Anwar, Naveed. "Identification and quantitive analysis of receptor mRNA in the rat pineal gland using competitive RT-PCR." Thesis, King's College London (University of London), 1998. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.286316.
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Junior, José Sinesio da Silva. "Os efeitos do treinamento físico aeróbio sobre a síntese de melatonina pineal em ratos." Universidade de São Paulo, 2015. http://www.teses.usp.br/teses/disponiveis/42/42137/tde-19022016-152711/.
Abstract:
A glândula pineal produz melatonina, estimulada pela liberação noturna de noradrenalina na pineal. O exercício físico aumenta a atividade dos neurônios simpáticos periféricos e a noradrenalina, o que modularia a síntese de melatonina. Porém há controvérsias, pois viu-se o aumento, a diminuição e a não alteração da síntese de melatonina induzida pelo exercício. Ademais, o diabetes induzido e o envelhecimento reduzem a síntese de melatonina pineal em ratos. Dessa maneira avaliou-se os efeitos do treinamento físico aeróbio sobre a síntese desse hormônio sob várias condições: animais adultos, diabéticos não tratados e idosos, sendo eles sedentários ou treinados. Nos adultos treinados não houve diferença na produção de melatonina, nos diabéticos não foi vista alteração na atividade da enzima AANAT e nos idosos treinados houve aumento na atividade da AANAT e na expressão gênica do receptor β adrenérgico no ZT18. Em suma, o treinamento físico não alterou a síntese de melatonina nos animais adultos e nos diabéticos, mas foi capaz de modulá-la nos animais idosos treinados.The pineal gland produces melatonin stimulated by the nocturnal release of norepinephrine. Physical exercise increases the activity of peripheral sympathetic neurons and norepinephrine release, which may modulate melatonin synthesis. Melatonin synthesis modulation by exercise remains controversial. On the other hand, induced diabetes and aging reduce the pineal melatonin synthesis. In this way, we assessed the effects of aerobic exercise training on the synthesis of this hormone under various conditions: adult, untreated diabetic and aged animals, either sedentary or trained. Physical exercise did not alter melatonin production in adult rats and diabetic ones showed no AANAT enzyme activity change. Trained aged animals presented no increase in AANAT activity and β-adrenergic receptor gene expression at ZT18. In conclusion, physical training did not alter melatonin synthesis in adult animals and in diabetic ones but was able to modulate it in trained aged animals.
47
Teo, Ee Hiok. ""The morphology of the pineal complex in the scincid lizard, Tiliqua rugosa" /." Title page, contents and abstract only, 1997. http://web4.library.adelaide.edu.au/theses/09PH/09pht314.pdf.
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Villela, Darine Christina Maia. "Síntese de melatonina na glândula pineal de ratos: modulação pelo glutamato." Universidade de São Paulo, 2008. http://www.teses.usp.br/teses/disponiveis/42/42137/tde-03062008-135402/.
Abstract:
Esse trabalho teve como objetivo estudar os efeitos do glutamato sobre a síntese de melatonina, avaliando a participação dos diferentes tipos de receptores e uma possível interação entre pinealócitos e astrócitos; além de avaliar o papel do fator de transcrição NF-kB nos efeitos modulatórios do glutamato. Para tanto, glândulas pineais de ratos foram mantidas em cultura e estimuladas com diferentes concentrações de glutamato e também com diversos agonistas glutamatérgicos. Culturas de pinealócitos isolados e co-culturas de pinealócitos e astrócitos também foram usadas. A melatonina foi quantificada em HPLC com detecção eletroquímica. Para caracterização dos receptores de glutamato foi feita uma análise de RT-PCR, e a ativação do NF-kB foi avaliada por ensaio de gel de retardo. Os resultados mostram que o glutamato exerce um efeito inibitório sobre a síntese de melatonina através de uma ação sobre os receptores metabotrópicos dos grupos I e II e ionotrópico do tipo AMPA e que as ações do glutamato são mediadas pela ativação do NF-kB dos astrócitos.The aim of this work was to study the effects of glutamate on melatonin synthesis, investigating the glutamate receptors involved and a possible interaction between the two predominant cell types of the pineal gland, pinealocytes and astrocytes; moreover, it was investigated the involvement of the transcription factor NF-kB on the glutamate effects. To accomplish this, pineal glands were kept in culture and stimulated with glutamate or glutamate agonists. Isolated pinealocytes or in association with astrocytes in culture were also stimulated with glutamate. Melatonin was quantified by HPLC with electrochemical detection. Glutamate receptors were characterized by RT-PCR and NF-kB activation was evaluated by gel shift assay. The data showed that glutamate has an inhibitory effect on melatonin synthesis that is mediated by groups I and II glutamate metabotropic receptors and AMPA receptor and that this effect involves the activation of astrocytic NF-kB.
49
Silva, Jessica Andrade da. "Papel da temporização noradrenérgica na regulação da síntese de melatonina pela glândula pineal em cultura: características funcionais e mecanismos de ação." Universidade de São Paulo, 2013. http://www.teses.usp.br/teses/disponiveis/42/42137/tde-20092013-112432/.
Abstract:
A glândula pineal de mamíferos não é uma estrutura oscilatória autônoma, exigindo a liberação de noradrenalina (Nor) na fase escura para que a melatonina seja circadianamente produzida. Na cultura padrão de glândula pineal, o órgão não expressa ritmicidade funcional e para mimetizar o padrão fisiológico de liberação de Nor, desenvolvemos a cultura temporizada com Nor. Logo, o objetivo desse trabalho foi investigar a manutenção do ritmo de expressão dos genes relógio pela cultura temporizada, e qual a via noradrenérgica envolvida. Para os estudos in vitro, realizaram-se culturas dos grupos: controle (sem Nor), agudo (cultura padrão) e temporizado (12h com Nor/12h sem Nor). Além disso, à cultura temporizada se adicionou Prasozin e/ou Propranolol. Analisou-se expressão dos genes relógio, atividade da enzima AANAT e conteúdo de melatonina no meio de cultura. No grupo temporizado, observou-se a manutenção da ritmicidade dos genes analisados, diferente do observado nos grupos controle, agudo e temporizado tratado com bloqueadores, além do aumento da atividade enzimática da AANAT e aumento do conteúdo de melatonina. Em suma, a cultura temporizada com Nor se mostra importante para evitar a arritmicidade encontrada na cultura padrão de glândula pineal.The mammals pineal gland is not an autonomous oscillator, the circadian melatonin synthesis requires the release of norepinephrine (NE) on the dark phase. In standard pineal gland culture, the glands do not express any functional rhythmicity. To mimic the physiological pattern of NE release in the pineal gland culture, we developed a synchronized culture with NE. We aimed to investigate the maintenance of circadian clock genes expression within rat pineal gland under acute and synchronized culture and the noradrenergic pathway involved. In in vitro experiments, culture glands were under: control (without NE), acute (standard culture) and synchronized (12h with NE/12h without NE) conditions. Furthermore, in the synchronized group were added Prasozin and/or Propranolol. We investigated clock genes expression, AANAT activity and melatonin content. The synchronized culture was able to maintain the rhythmic clock genes expression, which didn´t occur in control, acute and synchronized treated with blockers groups, and was able to improve AANAT activity and melatonin synthesis. In conclusion, synchronized culture method showed as a useful approach to avoid disruption of rhythmic variations found in the standard culture.
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Mesquita, Livia Silva Medeiros de. "Ações da metilecgonidina sobre a síntese de melatonina na glândula pineal de ratos." Universidade de São Paulo, 2012. http://www.teses.usp.br/teses/disponiveis/42/42137/tde-25072012-131207/.
Abstract:
A glândula pineal sintetiza o hormônio melatonina no período escuro. No rato, a ativação dos receptores a e b-adrenérgicos aumenta os níveis de AMPc, levando à síntese e ativação da enzima arilalquilamina-N-acetiltransferase (AANAT). A glândula recebe também inervação parassimpática, sendo inibitório o efeito da acetilcolina. A metilecgonidina (AEME) é o produto da pirólise da cocaína, quando esta é usada sob a forma de \"crack\". Neste trabalho estudamos os efeitos e os mecanismos de ação da AEME sobre a síntese da melatonina. Foram investigados a atividade da AANAT, o Ca2+, o AMPc e a viabilidade celular e a fragmentação do DNA. A AEME reduziu a síntese da melatonina in vivo e in vitro, sendo este efeito revertido pela atropina. A AEME induziu um aumento do Ca2+, não alterando o AMPc e a atividade da AANAT. A viabilidade celular e fragmentação do DNA não foram modificadas pela AEME. Em conclusão, a AEME reduz a síntese da melatonina, in vitro e in vivo, e a sua ação se dá por interferir com o sistema colinérgico muscarínico.The pineal gland synthesizes the hormone melatonin in the dark. In rats, the activation of a and b-adrenergic receptors increases cAMP levels and the synthesis and activity of arylalkylamine-N-acetyltransferase enzyme (AANAT). The pineal gland is also innervated by parasympathetic fibers, being inhibitory the effect of acetylcholine. Methylecgonidine (AEME) is the pyrolysis product of cocaine when it is used as \"crack.\" In this work we studied the effects of AEME on the melatonin synthesis, in vitro and in vivo. We investigated AANAT activity, iCa2+, cAMP, cell viability and DNA fragmentation. AEME reduced melatonin synthesis in vivo and in vitro, and this effect was reversed by atropine. There was an increase in Ca2+, but not in cAMP or AANAT activity induced by AEME. Cell viability and DNA fragmentation were not affected by AEME. In conclusion, AEME reduced melatonin synthesis in vitro and in vivo, being this effect mediated by the muscarinic cholinergic system.