Articoli di riviste: "Melatonin Physiological effect"

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Chakravarty, Shilpa, e Syed Ibrahim Rizvi. "Day and Night GSH and MDA Levels in Healthy Adults and Effects of Different Doses of Melatonin on These Parameters". International Journal of Cell Biology 2011 (2011): 1–5. http://dx.doi.org/10.1155/2011/404591.

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The pineal secretory product melatonin (chemically, N-acetyl-5-methoxytryptamine) acts as an effective antioxidant and free-radical scavenger and plays an important role in several physiological functions such as sleep induction, immunomodulation, cardiovascular protection, thermoregulation, neuroprotection, tumor-suppression and oncostasis. Membrane lipid-peroxidation in terms of malondialdehyde (MDA) and intracellular glutathione (GSH) is considered to be a reliable marker of oxidative stress. The present work was undertaken to study the modulating effect of melatonin on MDA and GSH in human erythrocytes during day and night. Our observation shows the modulation of these two biomarkers by melatonin, and this may have important therapeutic implications.In vitrodose-dependent effect of melatonin also showed variation during day and night. We explain our observations on the basis of melatonin's antioxidative function and its effect on the fluidity of plasma membrane of red blood cells. Rhythmic modulation of MDA and GSH contents emphasized the role of melatonin as an antioxidant and its function against oxidative stress.

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Zaminy, Arash, Iraj Ragerdi Kashani, Mohammad Barbarestani, Azim Hedayatpour, Reza Mahmoudi, Safoura Vardasbi e Mohammad Ali Shokrgozar. "Effects of melatonin on the proliferation and differentiation of rat adipose-derived stem cells". Indian Journal of Plastic Surgery 41, n. 01 (gennaio 2008): 08–14. http://dx.doi.org/10.1055/s-0039-1699220.

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ABSTRACT Background: Osteogenesis driven by adipose-derived stem cells (ADSCs) is regulated by physiological and pathological factors. Accumulating evidence from in vitro and in vivo experiments suggests that melatonin may have an influence on bone formation. However, little is known about the effects of melatonin on osteogenesis, which thus remains to be elucidated. This study was performed to determine whether melatonin at physiological concentrations (0.01-10 nM) could affect the in vitro proliferation and osteogenic differentiation of rat ADSCs.Materials and Methods: ADSCs were isolated from the fat of adult rats. After cell expansion in culture media and through three passages, osteogenesis was induced in a monolayer culture using osteogenic medium with or without melatonin at physiological concentrations (0.01-10 nM). After four weeks, the cultures were examined for mineralization by Alizarin Red S and von Kossa staining and for alkaline phosphatase (ALP) activity using an ALP kit. Cell viability and apoptosis were also assayed by 3-(4, 5-dimethylthiazol-2-yl)-5-(3-carboxymethoxyphenyl)-2-(4-sulfophenyl)-2H-tetrazolium (MTT) assay and flow cytometry, respectively.Results: The results indicated that at physiological concentrations, melatonin suppressed proliferation and differentiation of ADSCs. These data indicate that ADSCs exposed to melatonin, had a lower ALP activity in contrast to the cells exposed to osteogenic medium alone. Similarly, mineral deposition (calcium level) also decreased in the presence of melatonin. Flow cytometry confirmed that cell growth had decreased and that the numbers of apoptotic cells had increased.Conclusion: These results suggest that the physiological concentration of melatonin has a negative effect on ADSC osteogenesis.

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Fernández-Alegre, Estela, Indira Álvarez-Fernández, Juan Carlos Domínguez, Adriana Casao e Felipe Martínez-Pastor. "Melatonin Non-Linearly Modulates Bull Spermatozoa Motility and Physiology in Capacitating and Non-Capacitating Conditions". International Journal of Molecular Sciences 21, n. 8 (13 aprile 2020): 2701. http://dx.doi.org/10.3390/ijms21082701.

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Bull spermatozoa physiology may be modulated by melatonin. We washed ejaculated spermatozoa free of melatonin and incubated them (4 h, 38 °C) with 0-pM, 1-pM, 100-pM, 10-nM and 1-µM melatonin in TALP-HEPES (non-capacitating) and TALP-HEPES-heparin (capacitating). This range of concentrations encompassed the effects mediated by melatonin receptors (pM), intracellular targets (nM–µM) or antioxidant activity (µM). Treatment effects were assessed as motility changes by computer-assisted sperm analysis (CASA) of motility and physiological changes by flow cytometry. Melatonin effects were more evident in capacitating conditions, with 100 pM reducing motility and velocity (VCL) while increasing a “slow” subpopulation. All concentrations decreased apoptotic spermatozoa and stimulated mitochondrial activity in viable spermatozoa, with 100 pM–1 µM increasing acrosomal damage, 10 nM–1 µM increasing intracellular calcium and 1 pM reducing the response to a calcium-ionophore challenge. In non-capacitating media, 1 µM increased hyperactivation-related variables and decreased apoptotic spermatozoa; 100 pM–1 µM increased membrane disorders (related to capacitation); all concentrations decreased mitochondrial ROS production. Melatonin concentrations had a modal effect on bull spermatozoa, suggesting a capacitation-modulating role and protective effect at physiological concentrations (pM). Some effects may be of practical use, considering artificial reproductive techniques.

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Liu, Guoyin, Bing Li, Xiuqiong Li, Yunxie Wei, Debing Liu e Haitao Shi. "Comparative Physiological Analysis of Methyl Jasmonate in the Delay of Postharvest Physiological Deterioration and Cell Oxidative Damage in Cassava". Biomolecules 9, n. 9 (5 settembre 2019): 451. http://dx.doi.org/10.3390/biom9090451.

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The short postharvest life of cassava is mainly due to its rapid postharvest physiological deterioration (PPD) and cell oxidative damage, however, how to effectively control this remains elusive. In this study, South China 5 cassava slices were sprayed with water and methyl jasmonate (MeJA) to study the effects of MeJA on reactive oxygen species, antioxidant enzymes, quality, endogenous hormone levels, and melatonin biosynthesis genes. We found that exogenous MeJA could delay the deterioration rate for at least 36 h and alleviate cell oxidative damage through activation of superoxide dismutase, catalase, and peroxidase. Moreover, MeJA increased the concentrations of melatonin and gibberellin during PPD, which had a significant effect on regulating PPD. Notably, exogenous MeJA had a significant effect on maintaining cassava quality, as evidenced by increased ascorbic acid content and carotenoid content. Taken together, MeJA treatment is an effective and promising way to maintain a long postharvest life, alleviate cell oxidative damage, and regulate storage quality in cassava.

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Glebezdina, N. S., A. A. Olina, I. V. Nekrasova e E. M. Kuklina. "Molecular mechanisms of control of differentiation of regulatory t-lymphocytes by exogenous melatonin". Доклады Академии наук 484, n. 2 (13 aprile 2019): 224–27. http://dx.doi.org/10.31857/s0869-56524842224-227.

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We investigated the role of epiphyseal hormone melatonin in the differentiation of naive CD4+T cells into regulatory T cells (Treg). The hormone at physiological and pharmacological concentrations inhibited Treg differentiation, decreasing both the proportion of CD4+FOXP3+ cells in the culture and the level of TGF‑β, the key cytokine for this T cell subpopulation. The inhibitory effect of exogenous melatonin was due to its interaction with the membrane receptors MT1 and MT2. At the same time, the signals realized through RORa — the nuclear receptor for melatonin — stimulated Treg formation; however, they were considerably weaker than the signals from the membrane receptors and were overlapped by the latter. Since the Treg subpopulation plays an important role in physiological and pathological processes in the body, the revealed effects of melatonin should be taken into account in its therapeutic use.

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Iwan, Paulina, Jan Stepniak e Malgorzata Karbownik-Lewinska. "Cumulative Protective Effect of Melatonin and Indole-3-Propionic Acid against KIO3—Induced Lipid Peroxidation in Porcine Thyroid". Toxics 9, n. 5 (21 aprile 2021): 89. http://dx.doi.org/10.3390/toxics9050089.

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Iodine deficiency is the main environmental factor leading to thyroid cancer. At the same time iodine excess may also contribute to thyroid cancer. Potassium iodate (KIO3), which is broadly used in salt iodization program, may increase oxidative damage to membrane lipids (lipid peroxidation, LPO) under experimental conditions, with the strongest damaging effect at KIO3 concentration of ~10 mM (corresponding to physiological iodine concentration in the thyroid). Melatonin and indole-3-propionic acid (IPA) are effective antioxidative indoles, each of which protects against KIO3-induced LPO in the thyroid. The study aims to check if melatonin used together with IPA (in their highest achievable in vitro concentrations) reveals stronger protective effects against KIO3-induced LPO in porcine thyroid homogenates than each of these antioxidants used separately. Homogenates were incubated in the presence of KIO3 (200; 100; 50; 25; 20; 15; 10; 7.5; 5.0; 2.5; 1.25; 0.0 mM) without/with melatonin (5 mM) or without/with IPA (10 mM) or without/with melatonin + IPA, and then, to further clarify the narrow range of KIO3 concentrations, against which melatonin + IPA reveal cumulative protective effects, the following KIO3 concentrations were used: 20; 18.75; 17.5; 16.25; 15; 13.75; 12.5; 11.25; 10; 8.75; 7.5; 0.0 mM. Malondialdehyde + 4-hydroxyalkenals (MDA + 4-HDA) concentration (LPO index) was measured spectrophotometrically. Protective effects of melatonin + IPA were stronger than those revealed by each antioxidant used separately, but only when LPO was induced by KIO3 in concentrations from 18.75 mM to 8.75 mM, corresponding to physiological iodine concentration in the thyroid. In conclusion, melatonin and indole-3-propionic acid exert cumulative protective effects against oxidative damage caused by KIO3, when this prooxidant is used in concentrations close to physiological iodine concentrations in the thyroid. Therefore, the simultaneous administration of these two indoles should be considered to prevent more effectively oxidative damage (and thereby thyroid cancer formation) caused by iodine compounds applied in iodine prophylaxis.

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Yang, Lu, Sijia Bu, Shengxue Zhao, Ning Wang, Jiaxin Xiao, Feng He e Xuan Gao. "Transcriptome and physiological analysis of increase in drought stress tolerance by melatonin in tomato". PLOS ONE 17, n. 5 (17 maggio 2022): e0267594. http://dx.doi.org/10.1371/journal.pone.0267594.

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Drought stress seriously affects tomato growth, yield and quality. Previous reports have pointed out that melatonin (MT) can alleviate drought stress damage to tomato. To better understand the possible physiological and molecular mechanisms, chlorophyll fluorescence parameters and leaf transcriptome profiles were analyzed in the “Micro Tom” tomato cultivar with or without melatonin irrigation under normal and drought conditions. Polyethylene glycol 6000 (PEG6000) simulated continuous drought treatment reduced plant height, but melatonin treatment improved plant growth rate. Physiological parameter measurements revealed that the drought-induced decreases in maximum efficiency of photosystem II (PSII) photochemistry, the effective quantum yield of PSII, electron transfer rate, and photochemical quenching value caused by PEG6000 treatment were alleviated by melatonin treatment, which suggests a protective effect of melatonin on PSII. Comparative transcriptome analysis identified 447, 3982, 4526 and 3258 differentially expressed genes (DEGs) in the comparative groups plus-melatonin vs. minus-melatonin (no drought), drought vs. no drought (minus-melatonin), drought vs. no drought (melatonin) and plus-melatonin vs. minus-melatonin (drought), respectively. Gene Ontology and Kyoto Encyclopedia of Genes and Genomes analysis revealed that DEGs in the four comparative groups were involved in multiple metabolic processes and closely related to hormone signal transduction and transcription factors. Transcriptome data revealed that melatonin changed the expression pattern of most hormone signal transduction related DEGs induced by drought, and improved plant drought resistance by down-regulating the expression of linoleic acid catabolic enzyme genes. These results provide new insights into a probable mechanism of the melatonin-induced protection of photosynthesis and enhancement of drought tolerance in tomato plants.

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Bigham-Sadegh, Amin. "The Effects of Melatonin in Bone Healing". Open Access Journal of Veterinary Science & Research 3, n. 2 (2018): 1–8. http://dx.doi.org/10.23880/oajvsr-16000155.

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Melatonin, an endogenous hormone, regularly is produced in pineal gland. Suprachiasmatic nucleus and the light/dark cycle controls melatonin function. Melatonin doesn't act upon specific target tissue; it reaches all organs and tissues and enters all intra cellular structures like mitochondria and nucleus. Melatonin has an important effect on physiological processes of body including regulation of blood pressure, circadian rhythms, ovarian function, seasonal reproduction, and immune function. The general ef fects of melatonin in bone health were proposed by many researchers during the last years. First experiments studied the influence of the pineal gland on level of serum calcium. It has been saw that inhibition the melatonin biosynthesis by exposure of youn g rats to the fluorescent light decrease the concentration of calcium in the serum. The effects of melatonin on bone healing were investigated by scientists, and they observed which melatonin protects the bone from fracture. Studies have showed which melat onin has an influential role on bone - healing because of its regulation of bone cells, antioxidant properties, and promotion of angiogenesis actions. Scientists have been show that melatonin has aninfluential role in bone healing process due to its regulati on of bone cells, antioxidant properties, and promotion of angiogenesis actions.

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Raynaud, F., J. L. Miguel, B. Vivien-Roels, M. Masson-Pévet e P. Pévet. "The effect of 5-methoxytryptamine on golden hamster gonads is not a consequence of its acetylation into melatonin". Journal of Endocrinology 121, n. 3 (giugno 1989): 507–12. http://dx.doi.org/10.1677/joe.0.1210507.

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ABSTRACT Radioimmunoassay and high performance liquid chromatography were used to determine if the gonadal atrophy induced by late afternoon injections of 5-methoxytryptamine (5-MT) in golden hamsters kept under long photoperiod could be due to the acetylation of this compound into melatonin. An increase in plasma concentrations of melatonin (10–13 nmol/l) was detected 15 min after injection of 130 nmol 5-MT. An injection of 4·3 nmol melatonin generated a similar plasma concentration of melatonin. 5-MT (130 nmol) and melatonin (4·3 nmol) were then injected daily in the late afternoon to golden hamsters kept under long photoperiod. After 8 weeks, 5-MT induced total testicular regression, while melatonin induced partial atrophy only. Thus under these experimental conditions, 5-MT had a physiological activity independent of that of melatonin. Journal of Endocrinology (1989) 121, 507–512

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Prada, Claudia, Susan B. Udin, Allan F. Wiechmann e Irina V. Zhdanova. "Stimulation of Melatonin Receptors Decreases Calcium Levels in Xenopus Tectal Cells by Activating GABAC Receptors". Journal of Neurophysiology 94, n. 2 (agosto 2005): 968–78. http://dx.doi.org/10.1152/jn.01286.2004.

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To investigate the physiological effects of melatonin receptors in the Xenopus tectum, we have used the fluorescent indicator Fluo-4 AM to monitor calcium dynamics of cells in tectal slices. Bath application of KCl elicited fluorescence increases that were reduced by melatonin. This effect was stronger at the end of the light period than at the end of the dark period. Melatonin increased γ-aminobutyric acid-C (GABAC)–receptor activity, as demonstrated by the ability of the GABAC-receptor antagonists, picrotoxin and TPMPA, to abolish the effects of melatonin. In contrast, neither the GABAA-receptor antagonist bicuculline nor the GABAB-receptor antagonist CGP 35348 diminished the effects of melatonin. RT-PCR analyses revealed expression of the 3 known melatonin receptors, MT1 (Mel1a), MT2 (Mel1b), and Mel1c. Because the effect of melatonin on tectal calcium increases was antagonized by an MT2-selective antagonist, 4-P-PDOT, we performed Western blot analyses with an antibody to the MT2 receptor; the data indicate that the MT2 receptor is expressed primarily as a dimeric complex and is glycosylated. The receptor is present in higher amounts at the end of the light period than at the end of the dark period, in a pattern complementary to the changes in melatonin levels, which are higher during the night than during the day. These results imply that melatonin, acting by MT2 receptors, modulates GABAC receptor activity in the optic tectum and that this effect is influenced by the light–dark cycle.

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Song, Juhyun, So Mang Kang, Kyoung Min Lee e Jong Eun Lee. "The Protective Effect of Melatonin on Neural Stem Cell against LPS-Induced Inflammation". BioMed Research International 2015 (2015): 1–13. http://dx.doi.org/10.1155/2015/854359.

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Stem cell therapy for tissue regeneration has several limitations in the fact that transplanted cells could not survive for a long time. For solving these limitations, many studies have focused on the antioxidants to increase survival rate of neural stem cells (NSCs). Melatonin, an antioxidant synthesized in the pineal gland, plays multiple roles in various physiological mechanisms. Melatonin exerts neuroprotective effects in the central nervous system. To determine the effect of melatonin on NSCs which is in LPS-induced inflammatory stress state, we first investigated nitric oxide (NO) production and cytotoxicity using Griess reagent assays, LDH assay, and neurosphere counting. Also, we investigated the effect of melatonin on NSCs by measuring the mRNA levels of SOX2, TLX, and FGFR-2. In addition, western blot analyses were performed to examine the activation of PI3K/Akt/Nrf2 signaling in LPS-treated NSCs. In the present study, we suggested that melatonin inhibits NO production and protects NSCs against LPS-induced inflammatory stress. In addition, melatonin promoted the expression of SOX2 and activated the PI3K/Akt/Nrf2 signaling under LPS-induced inflammation condition. Based on our results, we conclude that melatonin may be an important factor for the survival and proliferation of NSCs in neuroinflammatory diseases.

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Iwan, Paulina, Jan Stepniak e Malgorzata Karbownik-Lewinska. "Pro-Oxidative Effect of KIO3 and Protective Effect of Melatonin in the Thyroid—Comparison to Other Tissues". Life 11, n. 6 (21 giugno 2021): 592. http://dx.doi.org/10.3390/life11060592.

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Not only iodine deficiency, but also its excess may contribute to thyroid cancer. Potassium iodate (KIO3), which is broadly used in the salt iodization program, can increase oxidative damage to membrane lipids (lipid peroxidation, LPO) under experimental conditions, with the strongest damaging effect at KIO3 concentration of ~10 mM (corresponding to physiological iodine concentration in the thyroid). Melatonin is an effective antioxidant, which protects against KIO3-induced LPO in the thyroid. This study aimed to compare the protective effects of melatonin, used in the highest achievable in vitro concentration, against KIO3-induced oxidative damage to membrane lipids in various porcine tissues (thyroid, ovary, liver, kidney, brain, spleen, and small intestine). Homogenates were incubated in the presence of KIO3 (20; 15; 10; 7.5; 5.0; 0.0 mM) without/with melatonin (5 mM). The malondialdehyde + 4-hydroxyalkenals (MDA + 4-HDA) concentration (LPO index) was measured spectrophotometrically. KIO3 increased the LPO in all examined tissues; in the thyroid, the damaging effect of KIO3 (10; and 7.5 mM) was lower than in other tissues and was not observed for the lowest concentration of 5 mM. Melatonin reduced LPO induced by KIO3 (10, 7.5, and 5 mM) in all tissues, and in the thyroid it was also protective against as high a concentration of KIO3 as 15 mM; the LPO level resulting from KIO3 + melatonin treatment was lower in the thyroid than in other tissues. In conclusion, the thyroid is less sensitive tothe pro-oxidative effects of KIO3 compared to other tissues. The strongest protective effect of melatonin was observed in the thyroid, but beneficial effects were significant also in other tissues. Melatonin should be considered to avoid the potential damaging effects of iodine compounds applied in iodine prophylaxis.

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Ogunkunle, Nathaniel, Friday Zakari, Felix Samuel e Bobwealth O. Omontese. "PSI-15 Effects of Melatonin on Behavioral and Physiological Responses of Weaned Beef Calves". Journal of Animal Science 100, Supplement_3 (21 settembre 2022): 234–35. http://dx.doi.org/10.1093/jas/skac247.425.

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Abstract Weaning is a stressful event often associated with changes in physiological characteristics, increased restlessness, reduced feed intake, and poor performance. This study was designed to evaluate the effects of melatonin on behavioral and physiological responses of weaned beef calves. Angus beef calves (n=36) at 7-mo of age were stratified by dam parity, body weight, calf sex and randomly allocated to receive either 24mg melatonin implants (MEL) or physiological saline (CON). A subset of calves were fitted with accelerometers on the hind leg to monitor activity levels for 7 days after weaning. Blood samples, rectal temperature, chute score and body weight measurements were collected on d 0, 7 and 14 after weaning. Activity of MEL calves was significantly (P < 0.05) lower than CON. The MEL calves had lower (P < 0.05) chute score on d 7 and 14 compared to CON. There was no marked effect of melatonin on rectal temperature and hematological parameters, however, platelet showed significant (P < 0.05) difference with MEL recording higher values compared to CON. Average daily gain (ADG) was 1.67 and 2.35kg/d in CON and MEL, respectively. We concluded that although no differences in ADG, hemogram, and rectal temperature were observed, melatonin treated calves had reduced behavioral stress response associated with weaning.

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Song, Runxian, Faujiah Nurhasanah Ritonga, Haiyang Yu, Changjun Ding e Xiyang Zhao. "Effects of Exogenous Antioxidant Melatonin on Physiological and Biochemical Characteristics of Populus cathayana × canadansis ‘Xin Lin 1’ under Salt and Alkaline Stress". Forests 13, n. 8 (13 agosto 2022): 1283. http://dx.doi.org/10.3390/f13081283.

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Salt and alkaline stress is one of the important problems restricting agricultural production and afforestation projects. This kind of stress will greatly limit the growth and development of forest trees. Recently, melatonin has been gradually realized as a strong kind of antioxidant due to its important regulatory and protective roles in the process of plant growth and development. This study takes Xin Lin 1 (Populus cathayana × canadansis ‘Xin Lin 1’) as the research object, and measures the changes of physiological indexes at different time points to verify the alleviation effect of melatonin under salt and alkaline stress. In this experiment, plants have different behaviors in the face of different levels of exogenous melatonin. Among them, low concentrations of melatonin (50 μM and 100 μM) were more helpful to reduce the levels of MDA and osmotic regulators in leaves. At this level, the SOD and CAT content in the leaves increased significantly. Melatonin at 800 μM was more inclined to induce POD, but its activity was not significantly induced. Overall, melatonin contributes to the secretion of ABA in plants and has a tendency to inhibit the content of SA. It is worth mentioning that the 100 μM melatonin treatment was more conducive to the secretion of IAA. To sum up, this experiment proves that melatonin has a dose effect in alleviating stress.

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Gilad, Eli, Haim Matzkin e Nava Zisapel. "Inactivation of Melatonin Receptors by Protein Kinase C in Human Prostate Epithelial Cells". Endocrinology 138, n. 10 (1 ottobre 1997): 4255–61. http://dx.doi.org/10.1210/endo.138.10.5269.

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Abstract The pineal hormone melatonin regulates seasonal reproduction and pubertal development in mammals. We recently found melatonin receptors in the human benign prostate tissue, primarily associated with the microsome-enriched fraction of the epithelial cells. In cultured benign prostate epithelial cells, melatonin, at physiological concentrations, suppressed [3H]thymidine incorporation and cGMP levels. The effects of melatonin were transient, suggesting inactivation of the receptors. In the present study, the possibility of inactivation of the prostate melatonin receptors by protein kinase C (PKC) was explored. Treatment of the microsome-enriched fraction with crude rat brain PKC in the presence of phorbol 12-myristate 13-acetate (TPA) or CaCl2 abolished the specific [125I]melatonin binding. This effect was prevented by the PKC inhibitor bisindolylmaleimide (GF-109203). [125I]Melatonin binding could be reinstated by iodoacetamide treatment. In benign prostate epithelial cells in culture, TPA pretreatment markedly reduced the apparent affinity of [125I]melatonin binding. In addition, TPA ablated the cells responses to melatonin, namely the suppression of [3H]thymidine incorporation and cGMP levels. Pretreatment with GF-109203 prevented the TPA effects on[ 125I]melatonin binding and responses. In addition, GF-109203 slowed down the inactivation of the melatonin-mediated inhibition of [3H]thymidine incorporation. Taken together, these data show that melatonin receptors are desensitized by PKC and imply that the transient response to melatonin may be the outcome of a direct or indirect melatonin-mediated activation of endogenous PKC.

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Ancel, Caroline, Agnete H. Bentsen, Marie-Emilie Sébert, Manuel Tena-Sempere, Jens D. Mikkelsen e Valérie Simonneaux. "Stimulatory Effect of RFRP-3 on the Gonadotrophic Axis in the Male Syrian Hamster: The Exception Proves the Rule". Endocrinology 153, n. 3 (1 marzo 2012): 1352–63. http://dx.doi.org/10.1210/en.2011-1622.

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In seasonal mammals, a distinct photoneuroendocrine circuit that involves the pineal hormone melatonin tightly synchronizes reproduction with seasons. In the Syrian hamster, a seasonal model in which sexual activity is inhibited by short days, we have previously shown that the potent GnRH stimulator, kisspeptin, is crucial to convey melatonin's message; however, the precise mechanisms through which melatonin affects kisspeptin remain unclear. Interestingly, rfrp gene expression in the neurons of the dorsomedial hypothalamic nucleus, a brain region in which melatonin receptors are present in the Syrian hamster, is strongly down-regulated by melatonin in short days. Because a large body of evidence now indicates that RFamide-related peptide (RFRP)-3, the product of the rfrp gene, is an inhibitor of gonadotropin secretion in various mammalian species, we sought to investigate its effect on the gonadotrophic axis in the Syrian hamster. We show that acute central injection of RFRP-3 induces c-Fos expression in GnRH neurons and increases LH, FSH, and testosterone secretion. Moreover, chronic central administration of RFRP-3 restores testicular activity and Kiss1 levels in the arcuate nucleus of hamsters despite persisting photoinhibitory conditions. By contrast RFRP-3 does not have a hypophysiotrophic effect. Overall, these findings demonstrate that, in the male Syrian hamster, RFRP-3 exerts a stimulatory effect on the reproductive axis, most likely via hypothalamic targets. This places RFRP-3 in a decisive position between the melatonergic message and Kiss1 seasonal regulation. Additionally, our data suggest for the first time that the function of this peptide depends on the species and the physiological status of the animal model.

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Souissi, Amine, Narimen Yousfi, Rim Dabboubi, Ghaith Aloui, Monoem Haddad e Nizar Souissi. "Effect of acute melatonin administration on physiological response to prolonged exercise". Biological Rhythm Research 51, n. 6 (7 febbraio 2019): 980–87. http://dx.doi.org/10.1080/09291016.2019.1573462.

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Guan, Qingyun, Zixu Wang, Jing Cao, Yulan Dong e Yaoxing Chen. "Mechanisms of Melatonin in Obesity: A Review". International Journal of Molecular Sciences 23, n. 1 (25 dicembre 2021): 218. http://dx.doi.org/10.3390/ijms23010218.

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Obesity and its complications have become a prominent global public health problem that severely threatens human health. Melatonin, originally known as an effective antioxidant, is an endogenous hormone found throughout the body that serves various physiological functions. In recent decades, increasing attention has been paid to its unique function in regulating energy metabolism, especially in glucose and lipid metabolism. Accumulating evidence has established the relationship between melatonin and obesity; nevertheless, not all preclinical and clinical evidence indicates the anti-obesity effect of melatonin, which makes it remain to conclude the clinical effect of melatonin in the fight against obesity. In this review, we have summarized the current knowledge of melatonin in regulating obesity-related symptoms, with emphasis on its underlying mechanisms. The role of melatonin in regulating the lipid profile, adipose tissue, oxidative stress, and inflammation, as well as the interactions of melatonin with the circadian rhythm, gut microbiota, sleep disorder, as well as the α7nAChR, the opioidergic system, and exosomes, make melatonin a promising agent to open new avenues in the intervention of obesity.

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Oliveira-Abreu, Klausen, Nathalia Silva-dos-Santos, Andrelina Coelho-de-Souza, Francisco Ferreira-da-Silva, Kerly Silva-Alves, Ana Cardoso-Teixeira, José Cipolla-Neto e José Leal-Cardoso. "Melatonin Reduces Excitability in Dorsal Root Ganglia Neurons with Inflection on the Repolarization Phase of the Action Potential". International Journal of Molecular Sciences 20, n. 11 (28 maggio 2019): 2611. http://dx.doi.org/10.3390/ijms20112611.

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Melatonin is a neurohormone produced and secreted at night by pineal gland. Many effects of melatonin have already been described, for example: Activation of potassium channels in the suprachiasmatic nucleus and inhibition of excitability of a sub-population of neurons of the dorsal root ganglia (DRG). The DRG is described as a structure with several neuronal populations. One classification, based on the repolarizing phase of the action potential (AP), divides DRG neurons into two types: Without (N0) and with (Ninf) inflection on the repolarization phase of the action potential. We have previously demonstrated that melatonin inhibits excitability in N0 neurons, and in the present work, we aimed to investigate the melatonin effects on the other neurons (Ninf) of the DRG neuronal population. This investigation was done using sharp microelectrode technique in the current clamp mode. Melatonin (0.01–1000.0 nM) showed inhibitory activity on neuronal excitability, which can be observed by the blockade of the AP and by the increase in rheobase. However, we observed that, while some neurons were sensitive to melatonin effect on excitability (excitability melatonin sensitive—EMS), other neurons were not sensitive to melatonin effect on excitability (excitability melatonin not sensitive—EMNS). Concerning the passive electrophysiological properties of the neurons, melatonin caused a hyperpolarization of the resting membrane potential in both cell types. Regarding the input resistance (Rin), melatonin did not change this parameter in the EMS cells, but increased its values in the EMNS cells. Melatonin also altered several AP parameters in EMS cells, the most conspicuously changed was the (dV/dt)max of AP depolarization, which is in coherence with melatonin effects on excitability. Otherwise, in EMNS cells, melatonin (0.1–1000.0 nM) induced no alteration of (dV/dt)max of AP depolarization. Thus, taking these data together, and the data of previous publication on melatonin effect on N0 neurons shows that this substance has a greater pharmacological potency on Ninf neurons. We suggest that melatonin has important physiological function related to Ninf neurons and this is likely to bear a potential relevant therapeutic use, since Ninf neurons are related to nociception.

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Sunyer-Figueres, Mercè, Jennifer Vázquez, Albert Mas, María-Jesús Torija e Gemma Beltran. "Transcriptomic Insights into the Effect of Melatonin in Saccharomyces cerevisiae in the Presence and Absence of Oxidative Stress". Antioxidants 9, n. 10 (1 ottobre 2020): 947. http://dx.doi.org/10.3390/antiox9100947.

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Abstract (sommario):

Melatonin is a ubiquitous indolamine that plays important roles in various aspects of biological processes in mammals. In Saccharomyces cerevisiae, melatonin has been reported to exhibit antioxidant properties and to modulate the expression of some genes involved in endogenous defense systems. The aim of this study was to elucidate the role of supplemented melatonin at the transcriptional level in S. cerevisiae in the presence and absence of oxidative stress. This was achieved by exposing yeast cells pretreated with different melatonin concentrations to hydrogen peroxide and assessing the entry of melatonin into the cell and the yeast response at the transcriptional level (by microarray and qPCR analyses) and the physiological level (by analyzing changes in the lipid composition and mitochondrial activity). We found that exogenous melatonin crossed cellular membranes at nanomolar concentrations and modulated the expression of many genes, mainly downregulating the expression of mitochondrial genes in the absence of oxidative stress, triggering a hypoxia-like response, and upregulating them under stress, mainly the cytochrome complex and electron transport chain. Other categories that were enriched by the effect of melatonin were related to transport, antioxidant activity, signaling, and carbohydrate and lipid metabolism. The overall results suggest that melatonin is able to reprogram the cellular machinery to achieve tolerance to oxidative stress.

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Chang, Tianliang, Yi Zhao, Hongyan He, Qianqian Xi, Jiayi Fu e Yuwei Zhao. "Exogenous melatonin improves growth in hulless barley seedlings under cold stress by influencing the expression rhythms of circadian clock genes". PeerJ 9 (22 gennaio 2021): e10740. http://dx.doi.org/10.7717/peerj.10740.

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Background Melatonin is a hormone substance that exists in various living organisms. Since it was discovered in the pineal gland of cattle in 1956, the function of melatonin in animals has been roughly clarified. Nevertheless, in plants, the research on melatonin is still insufficient. Hulless barley (Hordeum vulgare L. var. nudum hook. f.) is a crop that originates from cultivated barley in the east, usually grown on the Qinghai-Tibet Plateau, becoming the most important food crop in this area. Although the genome and transcriptome research of highland barley has gradually increased recently years, there are still many problems about how hulless barley adapts to the cold climate of the Qinghai-Tibet Plateau. Methods In this study, we set three temperature conditions 25°C, 15°C, 5°C hulless barley seedlings, and at the same time soaked the hulless barley seeds with a 1 µM melatonin solution for 12 hours before the hulless barley seeds germinated. Afterwards, the growth and physiological indicators of hulless barley seedlings under different treatment conditions were determined. Meanwhile, the qRT-PCR method was used to determine the transcription level of the hulless barley circadian clock genes under different treatment conditions under continuous light conditions. Results The results showed the possible mechanism by which melatonin pretreatment can promote the growth of hulless barley under cold stress conditions by studying the effect of melatonin on the rhythm of the circadian clock system and some physiological indicators. The results revealed that the application of 1 µM melatonin could alleviate the growth inhibition of hulless barley seedlings caused by cold stress. In addition, exogenous melatonin could also restore the circadian rhythmic oscillation of circadian clock genes, such as HvCCA1 and HvTOC1, whose circadian rhythmic phenotypes were lost due to environmental cold stress. Additionally, the results confirmed that exogenous melatonin even reduced the accumulation of key physiological indicators under cold stress, including malondialdehyde and soluble sugars. Discussion Overall, these findings revealed an important mechanism that exogenous melatonin alleviated the inhibition of plant vegetative growths either by restoring the disrupted circadian rhythmic expression oscillations of clock genes, or by regulating the accumulation profiles of pivotal physiological indicators under cold stress.

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Yang, Xiaolong, Yumeng Zhang, Ting Liu, Jiali Shi, Mingfang Qi, Yufeng Liu e Tianlai Li. "Integrated Physiological, Transcriptomic, and Proteomic Analyses Reveal the Regulatory Role of Melatonin in Tomato Plants’ Response to Low Night Temperature". Antioxidants 11, n. 10 (19 ottobre 2022): 2060. http://dx.doi.org/10.3390/antiox11102060.

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Abstract (sommario):

Melatonin is a direct free radical scavenger that has been demonstrated to increase plants’ resistance to a variety of stressors. Here, we sought to examine the effect of melatonin on tomato seedlings subjected to low night temperatures using an integrated physiological, transcriptomic, and proteomic approach. We found that a pretreatment with 100 μM melatonin increased photosynthetic and transpiration rates, stomatal apertures, and peroxidase activity, and reduced chloroplast damage of the tomato plant under a low night temperature. The melatonin pretreatment reduced the photoinhibition of photosystem I by regulating the balance of both donor- and acceptor-side restriction of PSI and by increasing electron transport. Furthermore, the melatonin pretreatment improved the photosynthetic performance of proton gradient regulation 5 (SlPGR5) and SlPGR5-like photosynthetic phenotype 1 (SlPGRL1)-suppressed transformants under a low night temperature stress. Transcriptomic and proteomic analyses found that the melatonin pretreatment resulted in the upregulation of genes and proteins related to transcription factors, signal transduction, environmental adaptation, and chloroplast integrity maintenance in low night temperature-stressed tomato plants. Collectively, our results suggest that melatonin can effectively improve the photosynthetic efficiency of tomato plants under a low night temperature and provide novel insights into the molecular mechanism of melatonin-mediated abiotic stress resistance.

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23

Kabiri, Rozita, Ali Hatami, Hakimeh Oloumi, Mehdi Naghizadeh, Fatemeh Nasibi e Zahra Tahmasebi. "Foliar application of melatonin induces tolerance to drought stress in Moldavian balm plants (Dracocephalum moldavica) through regulating the antioxidant system". Folia Horticulturae 30, n. 1 (1 giugno 2018): 155–67. http://dx.doi.org/10.2478/fhort-2018-0016.

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Abstract (sommario):

Abstract Melatonin, as an indoleamine molecule, regulates a wide range of physiological functions during the growth, morphogenesis and response of plants to biotic and abiotic stresses. In this research, the effect of exogenous application of melatonin (0 (distilled water), 50, 100 and 150 µM) to the leaves of Moldavian balm plants grown under different levels of drought stress (100% (control), 80%, 60% and 40% of field water capacity) was investigated. The results indicate that plants which were treated with 100 µM melatonin showed the greatest leaf surface area, lateral branching, flower length and activities of antioxidant enzymes (superoxide dismutase, guaiacol peroxidase and ascorbate peroxidase). Foliar application of 100 µM melatonin had no significant difference in catalase activity in comparison with the control and other concentrations of melatonin under normal, moderate and severe drought stress conditions. The lowest H2O2 content and lipid peroxidation (electrolyte leakage, concentrations of malondialdehyde and other aldehydes) were obtained at the concentration of 100 µM melatonin under severe drought stress. This concentration also significantly increased the chlorophyll content and enhanced the relative water content; however, foliar application of 100 µM melatonin had no significant effect on leaf length and proline content compared with the control under normal and stress conditions. The obtained results suggested that foliar application of 100 µM melatonin was more effective than the concentrations of 50 and 150 µM melatonin in reducing the adverse effects of moderate and severe drought stress.

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Rodríguez-Santana, César, Javier Florido, Laura Martínez-Ruiz, Alba López-Rodríguez, Darío Acuña-Castroviejo e Germaine Escames. "Role of Melatonin in Cancer: Effect on Clock Genes". International Journal of Molecular Sciences 24, n. 3 (18 gennaio 2023): 1919. http://dx.doi.org/10.3390/ijms24031919.

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Abstract (sommario):

The circadian clock is a regulatory system, with a periodicity of approximately 24 h, that generates rhythmic changes in many physiological processes. Increasing evidence links chronodisruption with aberrant functionality in clock gene expression, resulting in multiple diseases, including cancer. In this context, tumor cells have an altered circadian machinery compared to normal cells, which deregulates the cell cycle, repair mechanisms, energy metabolism and other processes. Melatonin is the main hormone produced by the pineal gland, whose production and secretion oscillates in accordance with the light:dark cycle. In addition, melatonin regulates the expression of clock genes, including those in cancer cells, which could play a key role in the numerous oncostatic effects of this hormone. This review aims to describe and clarify the role of clock genes in cancer, as well as the possible mechanisms of the action of melatonin through which it regulates the expression of the tumor’s circadian machinery, in order to propose future anti-neoplastic clinical treatments.

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Huether, G., M. Messner, A. Rodenbeck e R. Hardeland. "Effect of continuous melatonin infusions on steady-state plasma melatonin levels in rats under near physiological conditions". Journal of Pineal Research 24, n. 3 (aprile 1998): 146–51. http://dx.doi.org/10.1111/j.1600-079x.1998.tb00527.x.

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26

Megala, R., M. K. Kalarani, P. Jeyakumar, N. Senthil, R. Pushpam e M. Umapathi. "Standardization of optimum melatonin concentration for drought tolerance at germination and early development stage in rice (CO-54)". Journal of Applied and Natural Science 14, n. 3 (16 settembre 2022): 1022–30. http://dx.doi.org/10.31018/jans.v14i3.3766.

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Abstract (sommario):

Drought stress poses a serious threat to production and nutritional security. In recent years, foliar application of plant growth regulators (PGRs) and nutrients are increasingly employed to overcome physiological constraints resulting in enhanced crop production. Melatonin is a new biomolecule recently found to ameliorate the effect of biotic and abiotic stresses in crop plants. Hence, the present experiment was conducted to assess the optimum concentration of melatonin to mitigate the adverse effect of drought stress on germination and growth components in rice variety CO-54. In this experiment, PEG-mediated drought stress (-0.5 MPa) was imposed with different concentrations of melatonin (at doses of 50, 100, 150, 200, and 250 µM) seed treatments. Together, these results indicated that 200 µM melatonin-treated seeds showed a greater germination percentage (60%), root length (12.23cm), shoot length (8.23cm), fresh and dry weight (0.126g and 0.095g), high vigor index (1910.22), promptness index (64.83), and germination stress index (100) respectively. The result of this experiment provides a shred of strong evidence suggesting that seed treatment of 200 µM melatonin could be considered an effective technique for mitigating the detrimental effects of drought by promoting seed germination and thereby increasing the growth components of seedlings in rice. The study demonstrates that melatonin can shield rice seedlings from the effects of drought stress.

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Baburina, Yulia, Alexey Lomovsky e Olga Krestinina. "Melatonin as a Potential Multitherapeutic Agent". Journal of Personalized Medicine 11, n. 4 (6 aprile 2021): 274. http://dx.doi.org/10.3390/jpm11040274.

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Abstract (sommario):

Melatonin (N-acetyl-5-methoxytryptamine, MEL) is a hormone produced by the pineal gland that was discovered many years ago. The physiological roles of this hormone in the body are varied. The beneficial effects of MEL administration may be related to its influence on mitochondrial physiology. Mitochondrial dysfunction is considered an important factor in various physiological and pathological processes, such as the development of neurodegenerative and cardiovascular diseases, diabetes, various forms of liver disease, skeletal muscle disorders, and aging. Mitochondrial dysfunction induces an increase in the permeability of the inner membrane, which leads to the formation of a permeability transition pore (mPTP) in the mitochondria. The long-term administration of MEL has been shown to improve the functional state of mitochondria and inhibit the opening of the mPTP during aging. It is known that MEL is able to suppress the initiation, progression, angiogenesis, and metastasis of cancer as well as the sensitization of malignant cells to conventional chemotherapy and radiation therapy. This review summarizes the studies carried out by our group on the combined effect of MEL with chemotherapeutic agents (retinoic acid, cytarabine, and navitoclax) on the HL-60 cells used as a model of acute promyelocytic leukemia. Data on the effects of MEL on oxidative stress, aging, and heart failure are also reported.

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Cao, Yang, Peihua Du, Jiahao Ji, Xiaolong He, Jiran Zhang, Yuwei Shang, Huaite Liu, Jizhong Xu e Bowen Liang. "Ionomic Combined with Transcriptomic and Metabolomic Analyses to Explore the Mechanism Underlying the Effect of Melatonin in Relieving Nutrient Stress in Apple". International Journal of Molecular Sciences 23, n. 17 (30 agosto 2022): 9855. http://dx.doi.org/10.3390/ijms23179855.

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Abstract (sommario):

Nutrient stress harms plant growth and yield. Melatonin is a biologically active, multifunctional hormone that relieves abiotic stress in plants. Although previous studies have shown that melatonin plays an important role in improving nutrient-use efficiency, the mechanism of its regulation of nutrient stress remains unclear. In this study, melatonin was applied to apple plants under nutrient stress, and morphological indices, physiological and biochemical indices, and stomatal morphology were evaluated. The response of apple plants to nutrient deficiency and the melatonin mechanism to alleviate nutrient stress were analyzed by combining ionome, transcriptome, and metabolome. The results showed that exogenous melatonin significantly alleviated the inhibitory effect of nutritional stress on the growth of apple plants by regulating stomatal morphology, improving antioxidant enzyme activity, promoting ion absorption, and utilizing and changing the absorption and distribution of minerals throughout the plant. The transcriptome results showed that melatonin alleviated nutrient stress and promoted nutrient absorption and utilization by regulating glutathione metabolism and upregulating some metal ion transport genes. The metabolome results indicated that levels of oxalic acid, L-ascorbic acid, anthocyanins (cyanidin-3-O-galactoside), lignans (lirioresinol A and syringaresinol), and melatonin significantly increased after exogenous melatonin was applied to plants under nutrient stress. These differentially expressed genes and the increase in beneficial metabolites may explain how melatonin alleviates nutrient stress in plants.

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Schwartz, Christine, Mallory A. Ballinger e Matthew T. Andrews. "Melatonin receptor signaling contributes to neuroprotection upon arousal from torpor in thirteen-lined ground squirrels". American Journal of Physiology-Regulatory, Integrative and Comparative Physiology 309, n. 10 (15 novembre 2015): R1292—R1300. http://dx.doi.org/10.1152/ajpregu.00292.2015.

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Abstract (sommario):

The brain of mammalian hibernators is naturally protected. Hibernating ground squirrels undergo rapid and extreme changes in body temperature and brain perfusion as they cycle between lengthy torpor bouts and brief periods of euthermia called interbout arousals (IBAs). Arousal from torpor to IBA occurs rapidly, but there is no evidence of brain injury accompanying this extreme physiological transition. Production of the hormone melatonin accompanies arousal, suggesting that it plays a protective role at this time. Here, we investigated mechanisms of melatonin receptor-mediated protection in the brain of the hibernating ground squirrel. We administered the competitive melatonin receptor antagonist luzindole (30 mg/kg ip) to ground squirrels at the predicted end of a torpor bout, triggering an arousal. We found that luzindole-treated animals exhibited caspase-3 activity two times higher than vehicle-treated animals in the hypothalamus at midarousal ( P = 0.01), suggesting that melatonin receptor signaling is important for protection in this brain region. We also found a 30% decline in succinate-fueled mitochondrial respiration in luzindole-treated animals compared with vehicle-treated animals ( P = 0.019), suggesting that melatonin receptor signaling is important for optimal mitochondrial function during arousal from torpor. The mitochondrial effects of luzindole treatment were seen only during the hibernation season, indicating that this effect is specifically important for arousal from torpor. These data provide evidence for the protective role of melatonin receptor signaling during the extreme physiological transition that occurs when a hibernating mammal arouses from torpor and provide further evidence for regional and seasonal changes in the hibernator brain.

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SILALERT, Parichart, e Wattana PATTANAGUL. "Foliar application of melatonin alleviates the effects of drought stress in rice (Oryza sativa L.) seedlings". Notulae Botanicae Horti Agrobotanici Cluj-Napoca 49, n. 3 (3 settembre 2021): 12417. http://dx.doi.org/10.15835/nbha49312417.

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Abstract (sommario):

Melatonin (N-acetyl-5-methoxytryptamine) plays an essential role in abiotic stress in plants, but its mechanism in drought tolerance is unclear. To better understand the protective roles of melatonin against drought stress, we investigated the effect of foliar application with exogenous melatonin on plant growth, physiological responses, and antioxidant enzyme activities in rice seedlings under drought stress. Rice seedlings were grown for 21 days, and foliar sprayed with 0, 50, 100, 200, and 300 µM melatonin. The control plant was watered daily, while the others were subjected to drought stress by withholding water for seven days. The results showed that drought stress significantly reduced plant growth, relative water content, and chlorophyll content. Electrolyte leakage, malondialdehyde (MDA) content and hydrogen peroxide (H2O2) were also negatively affected by drought stress. Application of melatonin alleviated the effects of drought stress by increasing plant growth, improving relative water content and chlorophyll content, and decreasing electrolyte leakage, MDA, and H2O2. Foliar application with melatonin also increased antioxidant enzyme activities, including superoxide dismutase (SOD), catalase (CAT), ascorbate peroxidase (APX), and guaiacol peroxidase (GPX). In addition, melatonin also enhanced proline and total soluble sugar accumulation during drought stress. It is, therefore, suggested that foliar application with 100 µM melatonin was the most effective for reducing the adverse effects of drought stress in rice plants.

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Wang, Shujuan, Wenju Liu, Aiyou Wen, Bing Yang e Xunsheng Pang. "Luzindole and 4P-PDOT block the effect of melatonin on bovine granulosa cell apoptosis and cell cycle depending on its concentration". PeerJ 9 (8 marzo 2021): e10627. http://dx.doi.org/10.7717/peerj.10627.

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Abstract (sommario):

Granulosa cells play an essential physiological role in mediating the follicle development and survival or apoptosis of granulosa cells dictate the follicle development or atresia. The aim of this study was to investigate the role of high dose (10−5 M) and low dose (10−9 M) melatonin in bovine granulosa cells, and assess whether MT1 and MT2 inhibiter affect granulosa cells response to melatonin. We found that the high dose (10−5 M) and low dose (10−9 M) both could act as an essential role in modulating granulosa cells apoptosis, cell cycle and antioxidant. The beneficial effect could be related to that melatonin promoted the expression of Bcl2, Bcl-xl, SOD1 and GPX4, and inhibited Bax, caspase-3 and p53 expression. Moreover P21 expression was decreased in granulosa cells treated with the high dose (10−5 M) melatonin and increased in that treated with the low dose (10−9 M) melatonin. To further reveal the role of MT1 and MT2 in mediating the effect of melatonin on granulosa cells apoptosis, cell cycle and antioxidant, we found that the luzindole and 4P-PDOT did not affect the effect of high dose (10−5 M) melatonin on regulating Bcl2, Bax, caspase-3, SOD1, GPX4 and p53 expression, while blocked its effect on modulating Bcl-xl and P21expression. However, luzindole and 4P-PDOT disturbed the effect of low dose (10−9 M) melatonin on regulating Bcl2, Bax, caspase-3, Bcl-xl, SOD1, GPX4, and p53 expression. In conclusion, these results reveal that the effect of low dose (10−9 M) melatonin on granulosa cells apoptosis are mediated by MT1 and MT2, and the high dose (10−5 M) melatonin affect the granulosa cells apoptosis by other pathway, besides MT1 and MT2. Moreover MT1 and MT2 may work in concert to modulate bovine granulosa cells function by regulating cellular progression and apoptosis.

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Wallace, J. H., J. J. Robinson, S. Wigzell e R. P. Aitken. "The effect of melatonin on the peripheral concentrations of LH and progesterone post-oestrus and on conception rate in ewes". Proceedings of the British Society of Animal Production (1972) 1988 (marzo 1988): 54. http://dx.doi.org/10.1017/s0308229600016925.

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Abstract (sommario):

Previous studies have shown that for Scottish Blackface ewes kept under a natural photoperiod and exposed to the ram the daily administration of the indoleamine melatonin from June onwards advanced the breeding season and appeared to increase ovulation rate and subsequent litter size (Wigzell et al., 1986). In the primate, exposure to melatonin has been shown to stimulate progesterone production by the corpus luteum in an in vivo perfusion system (Webley & Hearn, 1987). Similarly melatonin administered at physiological concentrations stimulated progesterone production by bovine and human granulosa cell cultures (Webley & Luck, 1986).The present experiments were carried out to determine:-(a) whether or not melatonin enhances progesterone production and thereby the establishment of pregnancy and embryo survival in the ewe.(b) whether melatonin acts directly on the corpus luteum or indirectly via increased activity of the hypothalamic GnRH pulse generator.(c) whether or not the presence of the ram in the immediate post-oestrus period alters the endocrine status of the ewe and thereby influences conception.

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Ye, Fan, Junhong Guo, Pengfu Hou, Yongjun Wang, Fengbin Song, Peng Zhang e Xiangnan Li. "Impacts of Melatonin on Functionalities of Constructed Wetlands for Wastewater Treatment". Land 11, n. 11 (11 novembre 2022): 2022. http://dx.doi.org/10.3390/land11112022.

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Abstract (sommario):

Constructed wetlands (CWs) are effective wastewater treatment systems, relying on plant and substrate uptake and microbial depletion to remove pollutants. It has been reported that melatonin can promote plant growth and change the structure of microbial communities. The effects of melatonin on stress tolerance of plants have been extensively studied, while the effects of melatonin on the efficiency of wastewater treatment in constructed wetlands are rarely known. In the current study, 1 mM melatonin was added to the constructed wetland systems to determine physiological characteristics of Phragmites australis, microbial enzyme activity, and microbial community structure of CWs. Under melatonin treatment, the An and gs of Phragmites australis plants were significantly improved compared with the control. In addition, the contents of phosphate and total anion in the xylem sap of Phragmites australis significantly increased. However, the concentration of total phosphorus in the effluent did change significantly. Melatonin treatment improved the dehydrogenase activity and significantly improved the removal efficiency of NH4+-N in CWs. Furthermore, melatonin reduced the richness of the microbial community in CWs, while it increased the diversity of bacterial community and altered microbial composition. FARPROTAX analysis showed that melatonin increased the abundance of bacteria involved in nitrogen fixation and ureolysis, which may be related to the improvement of plant photosynthetic performance and improved rhizosphere oxygen environment. These results suggested that melatonin may affect plant performance and microbial composition and functions to improve the purification effect of constructed wetland.

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Kurtulmuş, Seda, e Tuğba Kök Taş. "Gıdalarda Bulunan L-Triptofan, Serotonin, Melatonin Profilleri ve Sağlık Üzerine Etkileri". Turkish Journal of Agriculture - Food Science and Technology 3, n. 11 (6 novembre 2015): 877. http://dx.doi.org/10.24925/turjaf.v3i11.877-885.355.

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Abstract (sommario):

Nowadays, depending on the progress of science and technology, our eating habits have changed. The shape and quality of nutrition is important for human health. Especially, some food components have various effect on central nervous system such as depression, anxiety, sleep, appetite. Food constituents are transported into the central nervous system via the neutral amino acids such as phenylalanine, leucine, isoleucine, tyrosine and valine. Amino acids have an important role in human nutrition. It cannot be synthesized in the body and one of the essential amino acids that must be taken outside, trytophan, is indispensable in human nutrition because of it has the many functions. In recent years, scientific community concentrated on the various functions of L-Trytophan (L-Trp) as pioneer in the secretion of the hormones serotonin and melatoninin in the human body. The hormones serotonin and melatonin is responsible for activities such as psychology, sleep, body temperature, blood pressure balance, antioxidant effect, cancer inhibitor, sexuality, autism and circadian rhythms in human body that they are available in various foods such as milk, kefir, yogurt, orange, strawberry, grape, olive oil, walnut, prune, nut, pomegranate, coffee, kiwi and banana. In this study, L-Trp, serotonin and melatonin biosynthesis and metabolism, food profiles and in terms of their physiological and biological effects on human health has been compiled.

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35

Rácz, Beáta, Michaela Dušková, Hana Jandíková, Martin Hill, Karel Vondra e Luboslav Stárka. "How Does Energy Intake Influence the Levels of Certain Steroids?" Prague Medical Report 116, n. 4 (2015): 290–302. http://dx.doi.org/10.14712/23362936.2015.68.

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Abstract (sommario):

The influence of steroid hormones on food intake is well described. However, there are only a few studies on the effect of food intake on steroid levels. The study involved eight non-smoker women (average age 29.48 ± 2.99 years; average BMI 21.3 ± 1.3 kg/m2); they did not use any kind of medication affecting steroidogenesis. We analysed the influence of four various stimuli on the levels of steroid hormones and melatonin. During their follicular phase of menstrual cycle, each woman had an oral glucose tolerance test (OGTT), intravenous glucose tolerance test (IVGTT), a standard breakfast and psyllium (a non-caloric fibre). Cortisol declined during each test, which is a physiological decline in the morning hours. In all tests (except of the application of the non-caloric fibre, psyllium), however, this decline was modified. After the standard breakfast there was an increase in cortisol at 40th minute. The OGTT and IVGTT tests led to a plateau in cortisol levels. Testosterone levels and those of other steroid hormones showed no relationships to tested stimulations. Oral and intravenous glucose have influenced physiological decline of melatonin levels. During the IVGTT test, melatonin levels started to increase at 20th minute, reaching a maximum at 40th minute. The OGTT test led to a delayed increase in melatonin levels, compared to IVGTT. Despite the fact that we performed the tests in the morning hours, when steroid hormone levels physiologically start to change due to their diurnal rhythm, we still found that food intake influences some of the hormone levels.

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Sarkar, Swaimanti, Aindrila Chattopadhyay e Debasish Bandyopadhyay. "Melatonin, the advance-guard in oxidative myocardial assault instigated by exercise stress: a physiological and biochemical insight". Melatonin Research 3, n. 4 (9 ottobre 2020): 451–75. http://dx.doi.org/10.32794/mr11250072.

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Abstract (sommario):

Exercise conducted at an optimum training load is usually beneficial for the overall health of an individual. However, an unaccustomed intense exercise carried out by untrained individuals or elite athletes during over-training and/or competition-related stress often bear inevitable cardiovascular risks. Although many alterations occurring in the cardiovascular system during exercise are the results of training adaptations, sudden cardiovascular deaths reported in competitive athletes is a matter of grave concern. Several oxidative biomarkers that depict the underlying structural and functional impairment of the myocardial tissue have been identified in the individuals subjected to extensive exercise. The exercise-mediated cardiomyopathy is free radical related and also associated with pro-inflammatory response. In this review we will highlight the possible role of melatonin in obviating irrevocable oxidative cardiovascular injury triggered by extensive exercise stress. Melatonin effectively reduces exercise-induced lipid peroxidation, restores natural cellular antioxidant pool and supresses the innate immune cascade reaction that, otherwise, jeopardize cardiovascular integrity. Melatonin blocks the IKK/IκB/NFκB signaling as well as suppress iNOS and COX-2 mediated inflammation in cardiac tissue. In addition, melatonin reduces blood lactate accumulation and accelerates glucose utilization, thereby, promoting energy metabolism in athletes during their training and competition. Physical exertion associated overheating and the resultant sympathetic outflow impede cardiovascular homeostasis. Melatonin not only attenuates the sympathomedullary stimulation but also protects the cardiac cells from the cytotoxic effect of catecholamines. The available information regarding the efficacy of melatonin in amelioration of exercise-driven oxidative insult in cardiac tissue has been discussed and summarized.

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Zhao, Zi-Yan, e Yvan Touitou. "Kinetic changes of melatonin release in rat pineal perifusions at different circadian stages. Effects of corticosteroids". Acta Endocrinologica 129, n. 1 (luglio 1993): 81–88. http://dx.doi.org/10.1530/acta.0.1290081.

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Abstract (sommario):

The kinetic characteristics of melatonin release were documented in perifused pineal glands removed from rats sacrificed at six circadian stages (light/dark =12:12): three during the light phase, i.e. 3, 7 and 11 hours after light onset (HALO), and three during the dark phase, i.e. 15, 19 and 23 HALO. Whatever the circadian stage, the melatonin release decreased during the first 3–4 h and then remained fairly constant and roughly similar up to 8 h of perifusion. However, the kinetics of the release in the first 3 h differed in perifusions of pineal glands removed during the light (progressive decline during 3 h) as compared to perifusions of pineal glands removed during the dark (sharp decline during the first hour and then a progressive decline until reaching a constant level after 3 h). As the effects of steroid administration on melatonin secretion are a matter of controversy, we also studied the direct effects and their circadian stage dependence, if any, of corticosterone, deoxycorticosterone and dexamethasone on melatonin secretion by pineal glands removed 7 HALO (about the middle of the light phase) and 19 HALO (about the middle of the dark phase). High concentrations of corticosterone (0.8 × 10−1 mol/l) and dexamethasone (0.4×10−3 mol/l) resulted in a significant (p<0.001) inhibitory effect on melatonin production (about a 50% and a 30% decrease, respectively) whatever the circadian stage, whereas lower concentrations (10−4–10−5 mol/l of both steroids did not affect melatonin production. In addition, neither pharmacological (1.06 × 10−5 mol/l) nor physiological (for the rat) concentrations (2.1 × 10−7 mol/l) of deoxycorticosterone had any significant effect on pineal melatonin production. These data clearly show the time dependence of the kinetics of melatonin release and an effect of adrenocortical steroids on pineal melatonin production that may be quite different according to the steroid and dosage.

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Carrascal, Livia, Pedro Nunez-Abades, Antonio Ayala e Mercedes Cano. "Role of Melatonin in the Inflammatory Process and its Therapeutic Potential". Current Pharmaceutical Design 24, n. 14 (13 luglio 2018): 1563–88. http://dx.doi.org/10.2174/1381612824666180426112832.

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Abstract (sommario):

Melatonin is an indolamine synthesized and secreted by the pineal gland along with other extrapineal sources including immune system cells, the brain, skin and the gastrointestinal tract. Growing interest in this compound as a potential therapeutic agent in several diseases stems from its pleiotropic effects. Thus, melatonin plays a key role in various physiological activities that include regulation of circadian rhythms, immune responses, the oxidative process, apoptosis or mitochondrial homeostasis. Most of these processes are altered during inflammatory pathologies, among which neurodegenerative and bowel diseases stand out. Therapeutic assays with melatonin indicate that it has a beneficial therapeutic value in the treatment of several inflammatory diseases, such as Alzheimer, Amiotrophic Lateral, Multiple Sclerosis and Huntigton´s disease as well as ulcerative colitis. However, contradictory effects have been demonstrated in Parkinson´s and Chron´s diseases, which, in some cases, the reported effects were beneficial while in others the pathology was exacerbated. These various results may be related to several factors. In the first place, it should be taken into account that at the beginning of the inflammation phase there is a production of reactive oxygen species (ROS) that should not be blocked by exclusively antioxidant molecules, since, on the one hand, it would be interfering with the action of neutrophils and macrophages and, on the other, with the apoptotic signals activated by ROS. It is also important to keep in mind that the end result of an anti-inflammatory molecule will depend on the degree of inflammation or whether or not it has been resolved and has therefore become chronic. In this review we present the use of melatonin in the control of inflammation underlying the above mentioned diseases. These actions are mediated through their receptors but also with their direct antioxidant action and melatonin's ability to break the vicious cycle of ROSinflammation. This review is aimed at evaluating the effect of melatonin on activity of the inflammatory process and at its immunomodulator effects.

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Zakari, Friday, Felix Samuel, Nathaniel Ogunkunle e Bobwealth O. Omontese. "PSI-16 Effects of Melatonin on Physiological Parameters, Chute and Exit Scores in Beef Calves Exposed to Summer Heat Stress". Journal of Animal Science 100, Supplement_3 (21 settembre 2022): 233–34. http://dx.doi.org/10.1093/jas/skac247.423.

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Abstract This study was designed to evaluate the effects of melatonin on rectal temperature (RT), respiratory rate (RR), heat shock protein 70 (HSP 70), growth hormone (GH), chute (CS) and exit scores (ES) in beef calves exposed to heat stress during the summer. A total of twenty (20) eight months old calves divided into 2 groups were used for the study: melatonin group (MEL, n = 10) received 24mg of melatonin, once every 28 days, and control group (CON, n = 10) did not receive any subcutaneous melatonin implant. The effect of melatonin on RT, RR, HSP 70, GH, chute (CS) and ES were evaluated biweekly (Day 0, 14, 28, 42, 56, 70). The mean ambient temperature (AT) 24.00 ± 0.21°C, relative humidity (RH) 81.60 ± 0.76 % and temperature-humidity index (THI) 89.97 ± 0.70 recorded during the study were above the normal range reported for calves. The biweekly fluctuation of weight gain (WG) in MEL were higher than the CON. The mean RT (39.40 ± 0.06°C), RR (62.57 ± 1.15 cpm), CS (1.13 ± 0.04) and ES (1.5 ± 0.09) in the MEL group were lower (P < 0.05) than the corresponding values of 40.10 ± 0.06°C, 71.53 ± 1.59 cpm, 1.40 ± 0.07 and 1.80 ± 0.10 in the CON group. The biweekly variations in RT, RR, CS, ES, HSP 70 were lower (P < 0.05) in the MEL than the CON. Growth hormone concentrations were higher at D56 and 70 in MEL compared to the CON. Our results demonstrated that MEL ameliorates heat stress during the summer by lowering RT, RR, CS, and ES of beef heifers during the study period. In addition, melatonin influenced the biweekly variation in WG, RT, RR, CS, ES, HSP 70 and GH of heifers during the study period.

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Yu, Yufeng, Liyuan Deng, Lu Zhou, Guanghui Chen e Yue Wang. "Exogenous Melatonin Activates Antioxidant Systems to Increase the Ability of Rice Seeds to Germinate under High Temperature Conditions". Plants 11, n. 7 (25 marzo 2022): 886. http://dx.doi.org/10.3390/plants11070886.

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High temperatures are a major concern that limit rice germination and plant growth. Although previous studies found that melatonin can promote seed germination, the physiological regulation mechanism by which exogenous melatonin mediates high temperature tolerance during rice seed germination is still largely unknown. In order to overcome these challenges, the present study investigates the effects of melatonin on the characteristics of rice seed germination as well as on antioxidant properties, under different high temperature conditions. The results show that 100 μM melatonin seed-soaking treatment under high temperature conditions effectively improves the germination potential, the germination index, and the vigor index of rice seeds; increases the length of the shoot and the root; improves the activity of the antioxidant enzymes; and significantly reduces the malondialdehyde content. The gray relational grade of the shoot peroxidase activity and the melatonin soaking treatment was the highest, which was used to evaluate the effect of melatonin on the heat tolerance of rice. The subordinate function method was used to comprehensively evaluate the tolerance, and the results show that the critical concentration of melatonin is 100 μM, and the critical interactive treatment is the germination at 38 °C and followed by the recovery at 26 °C for 1 day + 100 μM. In conclusion, 100 μM of melatonin concentration improved the heat resistance of rice seeds by enhancing the activity of the antioxidant enzymes.

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41

Arendt, J. "Miracle or myth? (Melatonin research)". Problems of Endocrinology 45, n. 3 (15 giugno 1999): 33–35. http://dx.doi.org/10.14341/probl11768.

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Abstract (sommario):

Perhaps more is said about melatonin today than about any other hormone. He is considered almost a panacea for all diseases, a source of youth; in terms of US sales, it currently competes with vitamin C and aspirin. Unfortunately, the role of melatonin is excessively exaggerated, and the claims are largely unfounded or supported only by data obtained in animal experiments [1, 2]. To clarify the mechanism of action of this hormone and its relationship with physiological chronobiology, much more research is needed. In particular, it remains to be determined the most optimal time of appointment and dosage of melatonin for people, allowing to achieve the maximum effect of this drug on the circadian rhythm of a person and on many functions dependent on it.

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Tan, Kexin, Jiangzhu Zheng, Cheng Liu, Xianghan Liu, Xiaomin Liu, Tengteng Gao, Xinyang Song, Zhiwei Wei, Fengwang Ma e Chao Li. "Heterologous Expression of the Melatonin-Related Gene HIOMT Improves Salt Tolerance in Malus domestica". International Journal of Molecular Sciences 22, n. 22 (17 novembre 2021): 12425. http://dx.doi.org/10.3390/ijms222212425.

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Abstract (sommario):

Melatonin, a widely known indoleamine molecule that mediates various animal and plant physiological processes, is formed from N-acetyl serotonin via N-acetylserotonin methyltransferase (ASMT). ASMT is an enzyme that catalyzes melatonin synthesis in plants in the rate-determining step and is homologous to hydroxyindole-O-methyltransferase (HIOMT) melatonin synthase in animals. To date, little is known about the effect of HIOMT on salinity in apple plants. Here, we explored the melatonin physiological function in the salinity condition response by heterologous expressing the homologous human HIOMT gene in apple plants. We discovered that the expression of melatonin-related gene (MdASMT) in apple plants was induced by salinity. Most notably, compared with the wild type, three transgenic lines indicated higher melatonin levels, and the heterologous expression of HIOMT enhanced the expression of melatonin synthesis genes. The transgenic lines showed reduced salt damage symptoms, lower relative electrolyte leakage, and less total chlorophyll loss from leaves under salt stress. Meanwhile, through enhanced activity of antioxidant enzymes, transgenic lines decreased the reactive oxygen species accumulation, downregulated the expression of the abscisic acid synthesis gene (MdNCED3), accordingly reducing the accumulation of abscisic acid under salt stress. Both mechanisms regulated morphological changes in the stomata synergistically, thereby mitigating damage to the plants’ photosynthetic ability. In addition, transgenic plants also effectively stabilized their ion balance, raised the expression of salt stress–related genes, as well as alleviated osmotic stress through changes in amino acid metabolism. In summary, heterologous expression of HIOMT improved the adaptation of apple leaves to salt stress, primarily by increasing melatonin concentration, maintaining a high photosynthetic capacity, reducing reactive oxygen species accumulation, and maintaining normal ion homeostasis.

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Ryg, Morten. "Physiological control of growth, reproduction and lactation in deer". Rangifer 6, n. 2 (1 giugno 1986): 261. http://dx.doi.org/10.7557/2.6.2.657.

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The physiological mechanisms controlling the growth, lactation and reproductive cycles of cervids, and the control of allocation of energy to different organs are discussed. The growth cycle may be secondary to an appetite cycle, regulated by changes in the secretion of prolactin, gonadal steroids, and possibly unknown factors. The reproductive cycle is controlled by changes in the release at the hypothalamic hormone GnRH, and by changes in the feedback effect of gonadal steroids. These cycles are probably the result of the timing effects of nutrition and changing photoperiod on an endogenous, circannual rhythm. The effect of photopenod is mediated by the pineal hormone melatonin. The physiological mechanisms controlling the partitioning of substrates between milk production, fetal growth and the tissues of the mother are poorly understood, but may involve changes in the secretion of growth hormone, insulin and triiodothyronine.

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Li, Yufei, Luqian Zhang, Yufeng Yu, Hongli Zeng, Liyuan Deng, Lifei Zhu, Guanghui Chen e Yue Wang. "Melatonin-Induced Resilience Strategies against the Damaging Impacts of Drought Stress in Rice". Agronomy 12, n. 4 (27 marzo 2022): 813. http://dx.doi.org/10.3390/agronomy12040813.

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Abstract (sommario):

Drought is a severe abiotic stress that imposes a serious threat to rice productivity. Although previous studies have found that melatonin can promote seed germination, the physiological regulation mechanism of drought tolerance in rice seed germination mediated by exogenous melatonin is still unclear. In order to overcome these challenges, polyethylene glycol 6000 (PEG6000) at concentrations of 20% and 35% was used to simulate osmotic stress. Rice seeds were treated with different concentrations of melatonin (i.e., 0, 20, 100, and 500 μM) to study the effects on germination characteristics, growth and development, superoxide dismutase (SOD) activity, peroxidase (POD) activity, catalase (CAT) activity, malondialdehyde (MDA) content, and soluble protein content. The results showed that the seed soaking treatment using melatonin at a concentration of 100 μM under drought stress effectively promoted the germination rate and improved the biomass of rice seed shoots and roots. Meanwhile, this treatment reduced MDA content to alleviate the oxidative damage of rice seeds caused by drought stress. The two-way ANOVA showed that the effect of single melatonin soaking treatment on rice seed germination was more significant than that of single drought stress and the interaction of drought stress and melatonin (p < 0.05). Using the membership function method, it was shown that the critical gradient of rice seeds under drought stress was 35%, and the critical treatment of interactive treatment was 35% + 100 μM. Through grey correlation analysis, it was found that germination rate (7 d) had the highest grey correlation with melatonin seed soaking treatment to evaluate the mitigation effect of melatonin on drought stress. This study provides a theoretical basis for light and simple cultivation technology for the dry direct seeding of rice.

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Zeng, Hongli, Minghao Liu, Xin Wang, Ling Liu, Huiyi Wu, Xuan Chen, Haodong Wang, Quansheng Shen, Guanghui Chen e Yue Wang. "Seed-Soaking with Melatonin for the Improvement of Seed Germination, Seedling Growth, and the Antioxidant Defense System under Flooding Stress". Agronomy 12, n. 8 (15 agosto 2022): 1918. http://dx.doi.org/10.3390/agronomy12081918.

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Abstract (sommario):

Flooding is the main cause of inhibited seed germination and seedling growth during the direct seeding of rice. As a growth-regulating hormone, melatonin plays an important role in promoting seed germination and enhancing plant stress resistance. However, there are still many unknown mechanisms related to the exogenous-melatonin-mediated regulation of submergence tolerance during seed germination. To overcome these challenges, this study investigated the effects of seed-soaking with different melatonin concentrations on the germination and physiological characteristics of rice seeds over different flooding times. The results showed that the exogenous administration of 100 μM of melatonin significantly improved the germination potential, germination rate, germination index, and vigor index of seeds and increased the size of the aboveground and underground biomass. By increasing the activities of superoxide dismutase (SOD) and peroxidase (POD) in shoots and roots, and reducing the content of malondialdehyde (MDA), the 100 μM melatonin alleviated the damage of rice seeds under flooding stress. The gray relational grade between the root MDA content and the melatonin seed-soaking treatment was the highest, and this was used to evaluate the effect of melatonin in alleviating flooding stress. A two-factor analysis of variance showed that the flooding stress treatment and the melatonin treatment had more significant effects on rice seed germination than the flooding and melatonin interaction treatments (p < 0.01). The optimal number of days for rice seeds to resist flooding stress was two, and the optimal concentration for the melatonin seed-soaking treatment was 100 μM. In sum, a 100 μM melatonin seed-soaking treatment can effectively alleviate the damage of flooding stress on rice seeds and promote the growth and development of seedlings. This study provides the theoretical basis for a light and simple cultivation technique for the direct seeding of rice.

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Hadi, Amir, Ehsan Ghaedi, Sajjad Moradi, Makan Pourmasoumi, Abed Ghavami e Marzieh Kafeshani. "Effects of Melatonin Supplementation On Blood Pressure: A Systematic Review and Meta-Analysis of Randomized Controlled Trials". Hormone and Metabolic Research 51, n. 03 (marzo 2019): 157–64. http://dx.doi.org/10.1055/a-0841-6638.

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AbstractMelatonin is a physiological indoleamine secreted from the pineal gland into the bloodstream. This hormone has antioxidant effects in cardiovascular disease, but the evidence regarding its effects on blood pressure (BP) has not been conclusive. Therefore, we assessed the impact of melatonin supplementation on systolic BP (SBP) and diastolic BP (DBP) through a systematic review and meta—analysis of available randomized controlled trials (RCTs). Medline, Scopus, Web of Science, Cochrane library, and Google scholar (until May 2018) were searched to identify potential RCTs with information on melatonin supplementation and BP. Mean Differences (MD) were pooled using a random-effects model. Standard methods were used for assessment of heterogeneity, sensitivity analysis, and publication bias. Pooling 5 RCTs (6 treatment arms) together identified significant reduction for SBP (MD: −3.43 mmHg, 95% confidence interval (CI): −5.76 to −1.09, p=0.004) and DBP (MD: −3.33 mmHg, 95% CI: −4.57 to −2.08, p<0.001) after supplementation with melatonin compared with control treatment. The sensitivity analysis indicated that the results were robust. We did not observe any evidence regarding publication bias. The findings of this meta-analysis support the overall favorable effect of melatonin supplementation on BP regulation.

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Al-Azawi, T. S. S., Majid H. Injidi, A. K. J. Rh,adi e A. A. W. Habib. "The role of melatonin in maintenance of immunological internal environment". Iraqi Journal of Veterinary Medicine 27, n. 1 (28 giugno 2003): 208–15. http://dx.doi.org/10.30539/ijvm.v27i1.1111.

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Melatonin hormone secretes from the pineal gland during dark period. This study was designed to investigate the effect of daily melatonin administration to chicks on some physiological parameters A total of fifty fawbro chicks of one day old were divided into two groups. The first group was given melatonin orally at a dose of 12ug/100g body weight daily for eight weeks and the other group was used as a control. During this experimental work the following parameters were studied. Daily feed and water intake, body temperature before and after melatonin administration with a general observation of chick's behaviour. Blood samples were collected weekly to study some parameters (total red blood cells, hemoglobin content, packed cell volume and differential leukocytic count). The results showed that, melatonin caused a drop of body temperature with relaxation and sleeping of chicks up to three hours after its administration. This period was accompanied by depression of feed and water intake. Total RBCs count, Hb, PCV, and lymphocytes were significantly increased with a decrease in heterophil / lymphocyte ratio. In conclusion, results of this investigation indicate that melatonin causes calming and sleeping of chicks and improves their feed conversion ratio.These results appear to be the first indication that melatonin does play an important role in immunity and improvement of blood picture. These effects were suggested to be due to the immuno – enhancing and anti-stress actio melatonin.

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Sasaki, Haruka, Yi Zhang, Charles W. Emala e Kentaro Mizuta. "Melatonin MT₂ receptor is expressed and potentiates contraction in human airway smooth muscle". American Journal of Physiology-Lung Cellular and Molecular Physiology 321, n. 6 (1 dicembre 2021): L991—L1005. http://dx.doi.org/10.1152/ajplung.00273.2021.

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Nocturnal asthma is characterized by heightened bronchial reactivity at night, and plasma melatonin concentrations are higher in patients with nocturnal asthma symptoms. Numerous physiological effects of melatonin are mediated via its specific G protein-coupled receptors (GPCRs) named the MT1 receptor, which couples to both Gq and Gi proteins, and the MT2 receptor, which couples to Gi. We investigated whether melatonin receptors are expressed on airway smooth muscle; whether they regulate intracellular cyclic AMP (cAMP) and calcium concentrations ([Ca2+]i), which modulate airway smooth muscle tone; and whether they promote airway smooth muscle cell proliferation. We detected the mRNA and protein expression of the melatonin MT2 but not the MT1 receptor in native human and guinea pig airway smooth muscle and cultured human airway smooth muscle (HASM) cells by RT-PCR, immunoblotting, and immunohistochemistry. Activation of melatonin MT2 receptors with either pharmacological concentrations of melatonin (10–100 µM) or the nonselective MT1/MT2 agonist ramelteon (10 µM) significantly inhibited forskolin-stimulated cAMP accumulation in HASM cells, which was reversed by the Gαi protein inhibitor pertussis toxin or knockdown of the MT2 receptor by its specific siRNA. Although melatonin by itself did not induce an initial [Ca2+]i increase and airway contraction, melatonin significantly potentiated acetylcholine-stimulated [Ca2+]i increases, stress fiber formation through the MT2 receptor in HASM cells, and attenuated the relaxant effect of isoproterenol in guinea pig trachea. These findings suggest that the melatonin MT2 receptor is expressed in ASM, and modulates airway smooth muscle tone via reduced cAMP production and increased [Ca2+]i.

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Yan, Huifang, e Peisheng Mao. "Comparative Time-Course Physiological Responses and Proteomic Analysis of Melatonin Priming on Promoting Germination in Aged Oat (Avena sativa L.) Seeds". International Journal of Molecular Sciences 22, n. 2 (15 gennaio 2021): 811. http://dx.doi.org/10.3390/ijms22020811.

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Abstract (sommario):

Melatonin priming is an effective strategy to improve the germination of aged oat (Avena sativa L.) seeds, but the mechanism involved in its time-course responses has remained largely unknown. In the present study, the phenotypic differences, ultrastructural changes, physiological characteristics, and proteomic profiles were examined in aged and melatonin-primed seed (with 10 μM melatonin treatment for 12, 24, and 36 h). Thus, 36 h priming (T36) had a better remediation effect on aged seeds, reflecting in the improved germinability and seedlings, relatively intact cell ultrastructures, and enhanced antioxidant capacity. Proteomic analysis revealed 201 differentially abundant proteins between aged and T36 seeds, of which 96 were up-accumulated. In melatonin-primed seeds, the restoration of membrane integrity by improved antioxidant capacity, which was affected by the stimulation of jasmonic acid synthesis via up-accumulation of 12-oxo-phytodienoic acid reductase, might be a candidate mechanism. Moreover, the relatively intact ultrastructures enabled amino acid metabolism and phenylpropanoid biosynthesis, which were closely associated with energy generation through intermediates of pyruvate, phosphoenolpyruvate, fumarate, and α-ketoglutarate, thus providing energy, active amino acids, and secondary metabolites necessary for germination improvement of aged seeds. These findings clarify the time-course related pathways associated with melatonin priming on promoting the germination of aged oat seeds.

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Shi, Xingyun, Shanshan Xu, Desheng Mu, Ehsan Sadeghnezhad, Qiang Li, Zonghuan Ma, Lianxin Zhao, Qinde Zhang e Lixin Wang. "Exogenous Melatonin Delays Dark-Induced Grape Leaf Senescence by Regulation of Antioxidant System and Senescence Associated Genes (SAGs)". Plants 8, n. 10 (23 settembre 2019): 366. http://dx.doi.org/10.3390/plants8100366.

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Leaf senescence is a developmentally programmed and degenerative process which comprises the last stage of the life cycle of leaves. In order to understand the melatonin effect on grapevine leaf senescence, the dark treatment on detached leaves of Vitis vinifera L. cv. Red Globe was performed to induce leaf senescence at short period of time. Then, a series of physiological and molecular changes in response to exogenous melatonin were measured. Results showed that 100 μM of melatonin treatment could significantly delay the dark induced leaf senescence, which is accompanied by the decreased production of reactive oxygen species (ROS). Meanwhile, melatonin treatment could increase the scavenging activity of antioxidant enzymes, such as peroxidase (POD), superoxide dismutase (SOD), and catalase (CAT). Simultaneously, ascorbate (AsA) and glutathione (GSH) contents, the activities of ascorbate peroxidase (APX), and glutathione reductase (GR) were significantly higher than control treatment in samples treated with melatonin. Furthermore, melatonin treatment showed to suppress the expression of leaf senescence-associated genes (SAGs). All these results demonstrated that melatonin could activate the antioxidant and Ascorbate-Glutathione (AsA-GSH) cycle system and repress the expression of SAGs that lead to delay the dark induced grape leaf senescence.

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