Littérature scientifique sur le sujet « AgRP neuron »
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Articles de revues sur le sujet "AgRP neuron"
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Oh, Youjin, Eun-Seon Yoo, Sang Hyeon Ju, Eunha Kim, Seulgi Lee, Seyun Kim, Kevin Wickman et Jong-Woo Sohn. « GIRK2 potassium channels expressed by the AgRP neurons decrease adiposity and body weight in mice ». PLOS Biology 21, no 8 (18 août 2023) : e3002252. http://dx.doi.org/10.1371/journal.pbio.3002252.
Texte intégralRésumé :
It is well known that the neuropeptide Y (NPY)/agouti-related peptide (AgRP) neurons increase appetite and decrease thermogenesis. Previous studies demonstrated that optogenetic and/or chemogenetic manipulations of NPY/AgRP neuronal activity alter food intake and/or energy expenditure (EE). However, little is known about intrinsic molecules regulating NPY/AgRP neuronal excitability to affect long-term metabolic function. Here, we found that the G protein-gated inwardly rectifying K+ (GIRK) channels are key to stabilize NPY/AgRP neurons and that NPY/AgRP neuron-selective deletion of the GIRK2 subunit results in a persistently increased excitability of the NPY/AgRP neurons. Interestingly, increased body weight and adiposity observed in the NPY/AgRP neuron-selective GIRK2 knockout mice were due to decreased sympathetic activity and EE, while food intake remained unchanged. The conditional knockout mice also showed compromised adaptation to coldness. In summary, our study identified GIRK2 as a key determinant of NPY/AgRP neuronal excitability and driver of EE in physiological and stress conditions.
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Klima, Michelle, Amber Alhadeff, Kayla Kruger, Santiago Pulido, Aaron McKnight et J. Nicholas Betley. « A Neural Circuit for the Suppression of Peripheral Inflammation by Hunger ». Journal of Immunology 204, no 1_Supplement (1 mai 2020) : 228.23. http://dx.doi.org/10.4049/jimmunol.204.supp.228.23.
Texte intégralRésumé :
Abstract Hunger is a primal biological drive that can initiate behavioral changes. Intuitively, hunger can inhibit behaviors such as sleep while simultaneously promoting foraging. Because pain can prevent an animal from seeking food we questioned if hunger could suppress pain. We found that food deprived mice reduce their response to inflammatory nociceptive stimuli. This reduction in nocifensive behavior during hunger is specific to inflammatory pain as the response to acute thermal and mechanical nociceptive stimuli remains intact. During hunger, agouti-related protein expressing (AgRP) neurons in the hypothalamus become active. AgRP neuron activation is both necessary and sufficient for feeding behavior and is thus a way to model hunger without the peripheral complications. Importantly, activating AgRP neurons recapitulates the analgesic effects of hunger. Because food deprivation reduces inflammatory pain responses, we next explored the influence of hunger and AgRP neuron activity on peripheral inflammation. To address this question, we measured paws after an injection of Complete Freund’s Adjuvant (CFA) in food deprived mice. We found that food deprivation was able to reduce CFA-induced paw inflammation compared to ad libitum fed controls. To assess the role of the AgRP circuit on inflammation, we measured CFA injected paws during optogenetic stimulation of AgRP neurons. Optogenetic activation of AgRP neurons rapidly reduces paw inflammation. This rapid and robust reduction in peripheral inflammation following activity in a CNS circuit suggests that AgRP neuron activity interacts with the immune system. Current experiments are aimed to determine the CNS à immune pathway that quickly reduces peripheral inflammation.
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Lin, Chiu-Ya, Kun-Yun Yeh, Hsin-Hung Lai et Guor Mour Her. « AgRP Neuron-Specific Ablation Represses Appetite, Energy Intake, and Somatic Growth in Larval Zebrafish ». Biomedicines 11, no 2 (9 février 2023) : 499. http://dx.doi.org/10.3390/biomedicines11020499.
Texte intégralRésumé :
Neuronal circuits regulating appetite are dominated by arcuate nucleus neurons, which include appetite-promoting and -suppressing neurons that release the orexigenic neuropeptide agouti-related protein (AgRP) and anorexigenic neuropeptide pro-opiomelanocortin, respectively, to compete for melanocortin receptors to modulate feeding behavior. In this study, we expressed novel agrp promoters, including different lengths of the 5’ flanking regions of the agrp gene (4749 bp) in the zebrafish genome. We used the agrp promoter to derive the enhanced green fluorescent protein (EGFP)-nitroreductase (NTR) fusion protein, allowing expression of the green fluorescence signal in the AgRP neurons. Then, we treated the transgenic zebrafish AgRP4.7NTR (Tg [agrp-EGFP-NTR]) with metronidazole to ablate the AgRP neurons in the larvae stage and observed a decline in their appetite and growth. The expression of most orexigenic and growth hormone/insulin-like growth factor axis genes decreased, whereas that of several anorexigenic genes increased. Our findings demonstrate that AgRP is a critical regulator of neuronal signaling for zebrafish appetite and energy intake control. Thus, AgRP4.7NTR can be used as a drug-screening platform for therapeutic targets to treat human appetite disorders, including obesity. Furthermore, the unique agrp promoter we identified can be a powerful tool for research on AgRP neurons, especially AgRP neuron-mediated pathways in the hypothalamus, and appetite.
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van de Wall, Esther, Rebecca Leshan, Allison W. Xu, Nina Balthasar, Roberto Coppari, Shun Mei Liu, Young Hwan Jo et al. « Collective and Individual Functions of Leptin Receptor Modulated Neurons Controlling Metabolism and Ingestion ». Endocrinology 149, no 4 (27 décembre 2007) : 1773–85. http://dx.doi.org/10.1210/en.2007-1132.
Texte intégralRésumé :
Two known types of leptin-responsive neurons reside within the arcuate nucleus: the agouti gene-related peptide (AgRP)/neuropeptide Y (NPY) neuron and the proopiomelanocortin (POMC) neuron. By deleting the leptin receptor gene (Lepr) specifically in AgRP/NPY and/or POMC neurons of mice, we examined the several and combined contributions of these neurons to leptin action. Body weight and adiposity were increased by Lepr deletion from AgRP and POMC neurons individually, and simultaneous deletion in both neurons (A+P LEPR-KO mice) further increased these measures. Young (periweaning) A+P LEPR-KO mice exhibit hyperphagia and decreased energy expenditure, with increased weight gain, oxidative sparing of triglycerides, and increased fat accumulation. Interestingly, however, many of these abnormalities were attenuated in adult animals, and high doses of leptin partially suppress food intake in the A+P LEPR-KO mice. Although mildly hyperinsulinemic, the A+P LEPR-KO mice displayed normal glucose tolerance and fertility. Thus, AgRP/NPY and POMC neurons each play mandatory roles in aspects of leptin-regulated energy homeostasis, high leptin levels in adult mice mitigate the importance of leptin-responsiveness in these neurons for components of energy balance, suggesting the presence of other leptin-regulated pathways that partially compensate for the lack of leptin action on the POMC and AgRP/NPY neurons.
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Padilla, Stephanie L., Jian Qiu, Casey C. Nestor, Chunguang Zhang, Arik W. Smith, Benjamin B. Whiddon, Oline K. Rønnekleiv, Martin J. Kelly et Richard D. Palmiter. « AgRP to Kiss1 neuron signaling links nutritional state and fertility ». Proceedings of the National Academy of Sciences 114, no 9 (14 février 2017) : 2413–18. http://dx.doi.org/10.1073/pnas.1621065114.
Texte intégralRésumé :
Mammalian reproductive function depends upon a neuroendocrine circuit that evokes the pulsatile release of gonadotropin hormones (luteinizing hormone and follicle-stimulating hormone) from the pituitary. This reproductive circuit is sensitive to metabolic perturbations. When challenged with starvation, insufficient energy reserves attenuate gonadotropin release, leading to infertility. The reproductive neuroendocrine circuit is well established, composed of two populations of kisspeptin-expressing neurons (located in the anteroventral periventricular hypothalamus, Kiss1AVPV, and arcuate hypothalamus, Kiss1ARH), which drive the pulsatile activity of gonadotropin-releasing hormone (GnRH) neurons. The reproductive axis is primarily regulated by gonadal steroid and circadian cues, but the starvation-sensitive input that inhibits this circuit during negative energy balance remains controversial. Agouti-related peptide (AgRP)-expressing neurons are activated during starvation and have been implicated in leptin-associated infertility. To test whether these neurons relay information to the reproductive circuit, we used AgRP-neuron ablation and optogenetics to explore connectivity in acute slice preparations. Stimulation of AgRP fibers revealed direct, inhibitory synaptic connections with Kiss1ARH and Kiss1AVPV neurons. In agreement with this finding, Kiss1ARH neurons received less presynaptic inhibition in the absence of AgRP neurons (neonatal toxin-induced ablation). To determine whether enhancing the activity of AgRP neurons is sufficient to attenuate fertility in vivo, we artificially activated them over a sustained period and monitored fertility. Chemogenetic activation with clozapine N-oxide resulted in delayed estrous cycles and decreased fertility. These findings are consistent with the idea that, during metabolic deficiency, AgRP signaling contributes to infertility by inhibiting Kiss1 neurons.
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Na, Junewoo, Byong Seo Park, Doohyeong Jang, Donggue Kim, Thai Hien Tu, Youngjae Ryu, Chang Man Ha et al. « Distinct Firing Activities of the Hypothalamic Arcuate Nucleus Neurons to Appetite Hormones ». International Journal of Molecular Sciences 23, no 5 (26 février 2022) : 2609. http://dx.doi.org/10.3390/ijms23052609.
Texte intégralRésumé :
The hypothalamic arcuate nucleus (Arc) is a central unit that controls the appetite through the integration of metabolic, hormonal, and neuronal afferent inputs. Agouti-related protein (AgRP), proopiomelanocortin (POMC), and dopaminergic neurons in the Arc differentially regulate feeding behaviors in response to hunger, satiety, and appetite, respectively. At the time of writing, the anatomical and electrophysiological characterization of these three neurons has not yet been intensively explored. Here, we interrogated the overall characterization of AgRP, POMC, and dopaminergic neurons using genetic mouse models, immunohistochemistry, and whole-cell patch recordings. We identified the distinct geographical location and intrinsic properties of each neuron in the Arc with the transgenic lines labelled with cell-specific reporter proteins. Moreover, AgRP, POMC, and dopaminergic neurons had different firing activities to ghrelin and leptin treatments. Ghrelin led to the increased firing rate of dopaminergic and AgRP neurons, and the decreased firing rate of POMC. In sharp contrast, leptin resulted in the decreased firing rate of AgRP neurons and the increased firing rate of POMC neurons, while it did not change the firing rate of dopaminergic neurons in Arc. These findings demonstrate the anatomical and physiological uniqueness of three hypothalamic Arc neurons to appetite control.
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Fang, Xing, Shujun Jiang, Jiangong Wang, Yu Bai, Chung Sub Kim, David Blake, Neal L. Weintraub, Yun Lei et Xin-Yun Lu. « Chronic unpredictable stress induces depression-related behaviors by suppressing AgRP neuron activity ». Molecular Psychiatry 26, no 6 (11 janvier 2021) : 2299–315. http://dx.doi.org/10.1038/s41380-020-01004-x.
Texte intégralRésumé :
AbstractPrevious studies have shown that AgRP neurons in the arcuate nucleus (ARC) respond to energy deficits and play a key role in the control of feeding behavior and metabolism. Here, we demonstrate that chronic unpredictable stress, an animal model of depression, decreases spontaneous firing rates, increases firing irregularity and alters the firing properties of AgRP neurons in both male and female mice. These changes are associated with enhanced inhibitory synaptic transmission and reduced intrinsic neuronal excitability. Chemogenetic inhibition of AgRP neurons increases susceptibility to subthreshold unpredictable stress. Conversely, chemogenetic activation of AgRP neurons completely reverses anhedonic and despair behaviors induced by chronic unpredictable stress. These results indicate that chronic stress induces maladaptive synaptic and intrinsic plasticity, leading to hypoactivity of AgRP neurons and subsequently causing behavioral changes. Our findings suggest that AgRP neurons in the ARC are a key component of neural circuitry involved in mediating depression-related behaviors and that increasing AgRP neuronal activity coule be a novel and effective treatment for depression.
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Huang, Hu, Seung Hwan Lee, Chianping Ye, Ines S. Lima, Byung-Chul Oh, Bradford B. Lowell, Janice M. Zabolotny et Young-Bum Kim. « ROCK1 in AgRP Neurons Regulates Energy Expenditure and Locomotor Activity in Male Mice ». Endocrinology 154, no 10 (1 octobre 2013) : 3660–70. http://dx.doi.org/10.1210/en.2013-1343.
Texte intégralRésumé :
Normal leptin signaling is essential for the maintenance of body weight homeostasis. Proopiomelanocortin- and agouti-related peptide (AgRP)-producing neurons play critical roles in regulating energy metabolism. Our recent work demonstrates that deletion of Rho-kinase 1 (ROCK1) in the AgRP neurons of mice increased body weight and adiposity. Here, we report that selective loss of ROCK1 in AgRP neurons caused a significant decrease in energy expenditure and locomotor activity of mice. These effects were independent of any change in food intake. Furthermore, AgRP neuron-specific ROCK1-deficient mice displayed central leptin resistance, as evidenced by impaired Signal Transducer and Activator of Transcription 3 activation in response to leptin administration. Leptin's ability to hyperpolarize and decrease firing rate of AgRP neurons was also abolished in the absence of ROCK1. Moreover, diet-induced and genetic forms of obesity resulted in reduced ROCK1 activity in murine arcuate nucleus. Of note, high-fat diet also impaired leptin-stimulated ROCK1 activity in arcuate nucleus, suggesting that a defect in hypothalamic ROCK1 activity may contribute to the pathogenesis of central leptin resistance in obesity. Together, these data demonstrate that ROCK1 activation in hypothalamic AgRP neurons is required for the homeostatic regulation of energy expenditure and adiposity. These results further support previous work identifying ROCK1 as a key regulator of energy balance and suggest that targeting ROCK1 in the hypothalamus may lead to development of antiobesity therapeutics.
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Liu, Yang, Ying Huang, Tiemin Liu, Hua Wu, Huxing Cui et Laurent Gautron. « Lipopolysacharide Rapidly and Completely Suppresses AgRP Neuron-Mediated Food Intake in Male Mice ». Endocrinology 157, no 6 (25 avril 2016) : 2380–92. http://dx.doi.org/10.1210/en.2015-2081.
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Although Agouti-related peptide (AgRP) neurons play a key role in the regulation of food intake, their contribution to the anorexia caused by proinflammatory insults has yet to be identified. Using a combination of neuroanatomical and pharmacogenetics experiments, this study sought to investigate the importance of AgRP neurons and downstream targets in the anorexia caused by the peripheral administration of a moderate dose of lipopolysaccharide (LPS) (100 μg/kg, ip). First, in the C57/Bl6 mouse, we demonstrated that LPS induced c-fos in select AgRP-innervated brain sites involved in feeding but not in any arcuate proopiomelanocortin neurons. Double immunohistochemistry further showed that LPS selectively induced c-Fos in a large subset of melanocortin 4 receptor-expressing neurons in the lateral parabrachial nucleus. Secondly, we used pharmacogenetics to stimulate the activity of AgRP neurons during the course of LPS-induced anorexia. In AgRP-Cre mice expressing the designer receptor hM3Dq-Gq only in AgRP neurons, the administration of the designer drug clozapine-N-oxide (CNO) induced robust food intake. Strikingly, CNO-mediated food intake was rapidly and completely blunted by the coadministration of LPS. Neuroanatomical experiments further indicated that LPS did not interfere with the ability of CNO to stimulate c-Fos in AgRP neurons. In summary, our findings combined together support the view that the stimulation of select AgRP-innervated brain sites and target neurons, rather than the inhibition of AgRP neurons themselves, is likely to contribute to the rapid suppression of food intake observed during acute bacterial endotoxemia.
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Coutinho, Eulalia A., Melanie Prescott, Sabine Hessler, Christopher J. Marshall, Allan E. Herbison et Rebecca E. Campbell. « Activation of a Classic Hunger Circuit Slows Luteinizing Hormone Pulsatility ». Neuroendocrinology 110, no 7-8 (21 octobre 2019) : 671–87. http://dx.doi.org/10.1159/000504225.
Texte intégralRésumé :
Introduction: The central regulation of fertility is carefully coordinated with energy homeostasis, and infertility is frequently the outcome of energy imbalance. Neurons in the hypothalamus expressing neuropeptide Y and agouti-related peptide (NPY/AgRP neurons) are strongly implicated in linking metabolic cues with fertility regulation. Objective: We aimed here to determine the impact of selectively activating NPY/AgRP neurons, critical regulators of metabolism, on the activity of luteinizing hormone (LH) pulse generation. Methods: We employed a suite of in vivo optogenetic and chemogenetic approaches with serial measurements of LH to determine the impact of selectively activating NPY/AgRP neurons on dynamic LH secretion. In addition, electrophysiological studies in ex vivo brain slices were employed to ascertain the functional impact of activating NPY/AgRP neurons on gonadotropin-releasing hormone (GnRH) neurons. Results: Selective activation of NPY/AgRP neurons significantly decreased post-castration LH secretion. This was observed in males and females, as well as in prenatally androgenized females that recapitulate the persistently elevated LH pulse frequency characteristic of polycystic ovary syndrome (PCOS). Reduced LH pulse frequency was also observed when optogenetic stimulation was restricted to NPY/AgRP fiber projections surrounding GnRH neuron cell bodies in the rostral preoptic area. However, electrophysiological studies in ex vivo brain slices indicated these effects were likely to be indirect. Conclusions: These data demonstrate the ability of NPY/AgRP neuronal signaling to modulate and, specifically, reduce GnRH/LH pulse generation. The findings suggest a mechanism by which increased activity of this hunger circuit, in response to negative energy balance, mediates impaired fertility in otherwise reproductively fit states, and highlight a potential mechanism to slow LH pulsatility in female infertility disorders, such as PCOS, that are associated with hyperactive LH secretion.
Thèses sur le sujet "AgRP neuron"
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Qu, Mengdi. « Molecular mechanism underlying CaMK1D-dependent function in AgRP neurons ». Electronic Thesis or Diss., Strasbourg, 2024. http://www.theses.fr/2024STRAJ029.
Texte intégralRésumé :
La perturbation des mécanismes de réponse au stress chez les organismes peut entraîner une dysfonction cellulaire et des maladies telles que le syndrome métabolique. L'équilibre énergétique est principalement régulé par le système nerveux central (SNC), qui intègre des signaux hormonaux, neuronaux et alimentaires provenant de divers tissus. Une dysfonction de ce système est liée à l'obésité et au syndrome métabolique, qui sont tous deux des précurseurs du diabète de type 2 (T2D). Notre laboratoire a découvert que la protéine kinase ID dépendante du calcium/calmoduline (CaMK1D), un gène associé au T2D, favorise la prise alimentaire médiée par la ghréline chez les souris. Cependant, le rôle de la signalisation de CaMK1D dans les neurones NPY/AgRP reste encore à éclaircir. Dans cette étude, nous avons réalisé un séquençage de l'ARN en utilisant la lignée cellulaire hypothalamique GT1-7. Nous avons ainsi découvert que CalHM6 est une cible potentielle en aval de la signalisation de CaMK1D. Les niveaux d'ARNm de CalHM6 sont ainsi significativement augmentés dans les cellules CaMK1D-/- et sont réduits lorsque CaMK1D est ré-exprimé. Cela a également été confirmé in vivo dans l'hypothalamus des souris CaMK1D-/-. CalHM6, probablement un canal calcique dépendant du voltage, a montré des niveaux intracellulaires de Ca2+ augmentés en réponse à la ghréline dans les cellules CaMK1D-/- par rapport aux cellules CaMK1D+/+ en utilisant la méthode jGCamps. En résumé, notre travail a montré que CalHM6 est une nouvelle cible de CaMK1D. Une expression élevée de CaMK1D, entraînant une faible expression de CalHM6, pourrait ainsi favoriser la prise alimentaire et l'obésité en modulant la signalisation dépendante du calcium dans les neurones NPY/AgRPDisruption of stress response mechanisms in organisms can lead to cellular dysfunction and diseases like metabolic syndrome. Energy balance is mainly regulated by the central nervous system (CNS), which integrates hormonal, neuronal, and dietary signals from various tissues. Dysfunction in this system is linked to obesity and metabolic syndrome, both precursors to type 2 diabetes (T2D). Our laboratory discovered that calcium/calmodulin-dependent protein kinase ID (CaMK1D), a gene associated with T2D, promotes ghrelin-mediated food intake in mice. However, CaMK1D signaling in NPY/AgRP neurons still remains questions. In this work, we proformed RNA sequencing using the GT1-7 hypothalamic cell line. To this end, we found that CalHM6 is a downstream target of CaMK1D signaling. CalHM6 mRNA levels were significantly upregulated in CaMK1D-/- cells and downregulated when CaMK1D was re-expressed. This was confirmed in vivo in the hypothalamus of CaMK1D-/- mice. CalHM6, likely a voltage-gated calcium channel, showed increased intracellular Ca2+ levels in response to ghrelin in CaMK1D-/- cells compared to CaMK1D+/+ cells using jGCamps method. Altogether, our work showed CalHM6 is a novel target of CaMK1D. High CaMK1D, leading to low CalHM6 expression, may enhance food intake and obesity by modulating calcium-dependent signaling in NPY/AgRP neuron
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Zagmutt, Caroca Sebastián. « Analysis of the in vivo effect of carnitine palmitoyltransferase 1A deletion in AgRP neurons ». Doctoral thesis, Universitat de Barcelona, 2020. http://hdl.handle.net/10803/671758.
Texte intégralRésumé :
Food intake and whole-body energy balance are regulated by the brain through a sophisticated neuronal network located mostly in the hypothalamus. In particular, the hypothalamic arcuate nucleus (ARC) is a fundamental sensor for the hormones and nutrients that inform about the energy state of the organism.
The ARC contains two populations of neurons with opposite functions: anorexigenic proopiomelanocortin (POMC)-expressing neurons and orexigenic Agouti-related protein (AgRP)- expressing neurons. Activation of AgRP neurons leads to an increase in food intake and a decrease in energy expenditure. It has been suggested that lipid metabolism in the ARC plays an important role in the central control of whole-body energy balance. Yet it is unclear whether lipid metabolism regulates the activity of AgRP neurons specifically. To answer this question, we studied mutant mice lacking carnitine palmitoyltransferase 1A (CPT1A) specifically in AgRP neurons (Cpt1aAgRP(-/-) mice). CPT1A regulates the rate-limiting step in the mitochondrial oxidation of fatty acids (FAs) and therefore plays a central role in the metabolism of lipids.
The results presented here demonstrated that the deletion of Cpt1a in AgRP neurons induces sex- based differences on the energy metabolism. Although male and female Cpt1aAgRP(-/-) mice showed a reduction of the body weight gain, both genders afford this reduction in different way. Male Cpt1aAgRP(-/-) mice showed a reduction of food intake with no changes in the energy expenditure, while female Cpt1aAgRP(-/-) mice increased the energy expenditure with no changes in food intake. Despite these results, the AgRP neuronal activation in fasting condition or by high levels of ghrelin were impaired in both genders. At a peripheral level, the deletion of Cpt1a in AgRP had an impact on different adipose tissues. On the one hand, the lack of Cpt1a in AgRP neurons activated the brown adipose tissue (BAT) activity, on the other hand, induced a substantial reduction of white adipose tissues, specially inguinal and gonadal fat pads.
Although AgRP neurons have been associated with solid food consumption, here we also reported that AgRP neurons could be involved in water homeostasis. Mice lacking CPT1A in AgRP neurons showed reduced levels of AV/ADH hormone and had impaired activation of center related with thirst. Finally, our results reveal that AgRP neurons requires Cpt1a to maintain a normal morphology and physiology. The deletion of Cpt1a in AgRP neurons does not affect the neuronal viability. However, interfered in the number of dendritic spines altering their morphology and normal state of the synapses.
Altogether, our results suggest that CPT1A and FAs oxidation in AgRP neurons impact peripheral energy balance highlighting this pathway as a possible target for therapeutic strategies to decrease body weight. We also provide evidence that AgRP could be involved in the regulation of water homeostasis.
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Huang, Cao Zhen Fang. « Neuronal circuits and reinforcement mechanisms underlying feeding behaviour ». Thesis, University of Cambridge, 2015. https://www.repository.cam.ac.uk/handle/1810/247221.
Texte intégralRésumé :
Animal survival depends on the brain’s ability to detect the energetic state of the body and to alter behaviour in order to maintain homeostasis. Current research in the control of food consumption stresses the importance of identifying and establishing the specific roles of homeostatic neurons, which sense the body’s energetic state and elicit complex and flexible food seeking behaviours. Recent developments in optogenetics, molecular genetics, and anatomical techniques have made these investigations possible at the resolution of specific cell types and circuits. These neurons are of particular interest because they serve as key entry points to the identification of downstream circuits and reinforcement mechanisms that control feeding behaviour. This dissertation probes the role of two kinds of homeostatic neurons— agouti-related peptide (AGRP) in the arcuate nucleus (ARC) and leptin receptor (LepRb) neurons in the lateral hypothalamic area (LHA)—in the control of food intake. First, I examined the role of LepRb neurons in the LHA in feeding. Results from electrophysiological studies indicate that these neurons consist of a subpopulation of homeostatic sensing LHA γ-aminobutyric acid (GABA) expressing neurons. In addition to their response to leptin, these neurons are capable of modulating their activity in response to changes in glucose levels, further substantiating their role as homeostatic sensing neurons. Behavioural studies using optogenetic activation of these neurons show that their elevated activity is capable of reducing body weight, although their role in modulating feeding remains unclear. Second, I investigated the reinforcement mechanisms employed by AGRP neurons to elicit voracious food consumption and increased willingness to work for food. Conditioned place avoidance studies under optogenetic activation of AGRP neurons reveal that their increased activity has negative valence and is avoided. In addition, imposition of elevated AGRP neuron activity in an operant task reduced instrumental food seeking with particular sensitivity under high effort requirements. Taken together, these results suggest that AGRP neurons employ a negative reinforcement teaching signal to direct action selection during food seeking and consumption. Third, I systematically analyzed the contribution of specific AGRP neuron projection subpopulations in AGRP neuron mediated evoked-feeding behaviour. Optogenetic activation studies of AGRP neuron axons in downstream projection regions indicate that several, but not all, subpopulations are capable of independently evoke food consumption. This work reveals a parallel and redundant functional circuit organization for AGRP neurons in the control of food intake. Interestingly, all AGRP neuron subpopulations examined displayed similar modulation by states of energy deficit and signals of starvation, despite their apparent divergence in function. As a whole, this dissertation extends our understanding of the role of homeostatic neurons in food consumption and uncovers previously unappreciated functional organization and reinforcement mechanisms employed by neuronal circuits that control feeding behaviour.
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Ramírez, Flores Sara. « Hypothalamic Ceramide Levels regulated by CPT1C mediate the Orexigenic effect of Ghrelin ». Doctoral thesis, Universitat Internacional de Catalunya, 2014. http://hdl.handle.net/10803/276184.
Texte intégralRésumé :
Recent data suggest that ghrelin exerts its orexigenic action through regulation of hypothalamic AMP-activated protein kinase pathway, leading to a decline in malonyl-CoA levels and desinhibition of carnitine palmitoyltransferase 1A (CPT1A), which increases mitochondrial fatty acid oxidation and ultimately enhances the expression of the orexigenic neuropeptides agouti-related protein (AgRP) and neuropeptide Y (NPY). However, it is unclear whether the brain-specific isoform CPT1C, which is located in the endoplasmic reticulum of neurons, may play a role in this action. Here, we demonstrate that the orexigenic action of ghrelin is totally blunted in CPT1C knockout (KO) mice, despite having the canonical ghrelin signaling pathway activated. We also demonstrate that ghrelin elicits a marked upregulation of hypothalamic C18:0 ceramide levels mediated by CPT1C. Notably, central inhibition of ceramide synthesis with myriocin negated the orexigenic action of ghrelin and normalized the levels of AgRP and NPY, as well as their key transcription factors phosphorylated cAMP-response element-binding protein and forkhead box O1. Furthermore, central treatment with ceramide induced food intake and orexigenic neuropeptides expression in CPT1C KO mice. Third, we demonstrate that ceramides act increasing the BSX expression, the transcription factor that works coordinately with pCREB and FoxO1 to increase orexigenic neuropeptides. Finally we link CPT1C and longevity as we have seen that CPT1CKO mice have reduced lifespan. Overall, these data indicate that, in addition to formerly reported mechanisms, ghrelin also induces food intake through regulation of hypothalamic CPT1C and ceramide metabolism
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Haverty, Maureen. « The microstructure, texture and thermal expansion of nuclear graphite ». Thesis, University of Manchester, 2015. https://www.research.manchester.ac.uk/portal/en/theses/the-microstructure-texture-and-thermal-expansion-of-nuclear-graphite(5fef7053-d4ca-42b8-a203-d5b2e6d5bedc).html.
Texte intégralRésumé :
It is proposed to continue operating the graphite moderated Advanced Gas-cooled Reactor (AGR) fleet past its design life. Nuclear graphite's properties change in reactor and our limited mechanistic understanding of the relationship between graphite structure, across different lengthscales, and its properties limits our ability to predict its future behaviour. An improved understanding of the relationship between graphite's structural features, the relationship between features across different lengthscales and their effect on material properties would all contribute to a mechanistic understanding of graphite behaviour. Thermal expansion generates thermal strains and stresses in the graphite core during thermal transients, such as during reactor start-up and shut-down. Thermal expansion is a function of graphite crystal thermal expansion, crystallographic preferred orientation and microstructure, although the exact relationship between these is not understood. It is also altered by neutron irradiation. This thesis investigates graphite microstructure, virgin and irradiated, and its crystallographic preferred orientation, specifically as they pertain to thermal expansion. The microstructure of British nuclear graphites PGA and Gilsocarbon, used in the Magnox and AGR fleet respectively, have been investigated using scanning electron microscopy (SEM). Trepanned AGR graphite, that is, graphite drilled from the reactor brick during routine inspection is examined. These samples are from the 2012 Hinkley Point B inspection campaign and are taken from several points through the brick thickness. This provides a 'snap shot' of current AGR graphite condition. Deep trepan samples removed from further into the brick thickness are observed for the first time. Neutron damage was observed in Magnox graphite, irradiated in an inert environment in the material test reactor programme INEEL. The spatial variation in texture of PGA and Gilsocarbon, and the change in such texture after prestress was observed using synchrotron x-ray diffraction. Numerical models were used to identify the required texture change to produce changes in CTE, observed by other authors, during in-situ stress. PGA filler lamellae are arranged in parallel arrays and Gilsocarbon's smaller platelets are arranged in bunched clusters. Severe radiolytic oxidation is observed at all trepan locations, with oxidation decreasing away from the fuel. Radiolytic oxidation occurs at platelet edges. Texture measurements have indicated that PGA graphite exhibits significant spatial variation in texture. Gilsocarbon exhibits less variation but the variation observed is large enough to cause increased thermal stresses. Texture measurements of prestressed graphite have indicated that texture changes also vary spatially. Texture results and SEM observations indicate that spatial variation in texture is caused by spatial variation in microstructure. Changes to the filler particle during prestress may alter local texture. These results indicate there is a link between nuclear graphite's microstructure and its texture. The texture, a function of lamellae or platelet arrangement, determines its thermal expansion. Spatial variations in microstructure formed during manufacturing leads to spatial variations in CTE and possibly other texture sensitive properties, such as dimensional change. Deformation of the lamellae or platelets during stress; thermal creep or irradiation creep is expected to contribute to the observed change in properties associated with these stimuli.
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Buccarello, L. « EFFECTS OF DIFFERENT DIETS IN A MOUSE MODEL OF NEURODEGENERATIVE DISEASE ». Doctoral thesis, Università degli Studi di Milano, 2015. http://hdl.handle.net/2434/339393.
Texte intégralRésumé :
Effects of different diets in a mouse model of neurodegeneration
Abstract
Tauopathies are neurodegenerative disorders characterized by the accumulation of abnormal Tau protein leading to cognitive and/or motor dysfunction; several studies suggest that dietary manipulations are increasingly viewed as possible approaches to treating neurodegenerative diseases. The mouse model chosen for this study was P301L; mice expressing P301L mutant Tau mimics features of human tauopathies and provides a model for investigating the neuropathogenesis of diseases. In this study we investigate at 7 and 15 months of age the effects of different diets (high fat-protein diet and low fat-protein diet) on P301L TG and CTR mice valuating metabolic, behavioral and cognitive activities; for the metabolic activities we analyzed survival rate, body weight gain and food and water consumption of animals. For behavioral activities we valuated mnemonic, locomotor and exploratory performances of animals; for cognitive activities we investigated the cognitive impairment (identifying agglomerates of hyperphosphorylated tau, neuronal loss, astrogliosis and oxidative damage) using immunohistochemical analysis and neuronal counts. We characterized P301L TG mouse model (trial 1-3) that replicated the impairments found in patients affected by tauophaty in a way age-gender-dependent showing in female TG mice a strong cognitive impairment strictly correlated with an increase in P-Tau, in both cerebral cortex and hippocampus, as well as astrogliosis and oxidative damage. We found an improvement of pathological conditions in TG mice administrating a low fat-protein diet in a way age-gender-dependent (trial 2-3), occurred with an increased lifespan, a reduction of food and water consumption, a reduction of aggregates of P-Tau, neuronal loss, astrogliosis and oxidative damage. We found an interaction between tauophaty and consumption of high fat-protein expressed on peripheral organs as hepatic insulin resistance and fatty accumulation in the liver, which induced nonalcoholic fatty liver disease in TG mice (trial 4). The correlation between P-Tau, insulin/IGF resistance and high fat-protein diet consumption was expressed by a condition of hepatomegaly characterized by the presence of lobular inflammatory infiltrate and deposits of collagen in liver and spleen, an increase of weight and size of liver and spleen, the highest increase of median levels of triglycerides, AST and ALT in P301L TG mice fed with high-fat protein diet in a way age-gender-dependent. In summary, we demonstrated the importance of interaction between nutrition and neurodegeneration and the role that different diets can have on the onset and development of tauophaty, obtaining an improvement of pathological conditions administrating a low fat-protein diet. Results obtained in this study suggest that P301L-Tau model could represent a valuable tool to study the role and the mechanisms through hyperphosphorylation and Tau aggregation leading to cognitive and memory impairment. Using the influence of nutrition for preventing or reducing the accumulation of hyperphosphorylated tau in this model could finally lead to the development of preventive potential treatments for tauopathies.
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Mascanzoni, Elisa. « Epidemiology of herbicide resistance evolution in rice weeds and variability in Echinochloa spp ». Doctoral thesis, Università degli studi di Padova, 2018. http://hdl.handle.net/11577/3425887.
Texte intégralRésumé :
Resistance issues has geometrically increased in the last ten years and now are affecting the production of all most important crops worldwide. Italy is the first European rice producer with about 230,000 ha cultivate mostly in the north west of the Po Valley. To date six weeds have evolved resistance in this crop, among these the most troublesome is Echinochloa spp. Two main purposes were followed in the research: first it was performed an epidemiological study at a scale as large as the main rice area, second a classification study was done on Echinochloa spp. including a dose response experiment of different species belonging to this genus to herbicides. The aim of epidemiological study was to investigate, at municipality level, the association between herbicide resistance cases identified so far and three important agronomic predictors: water seeding rate, soil texture and rotation rate. The analyses was performed using different statistical tests: discriminant analyses and logistic regressions were used to find the degree of association between resistance presence and the predictors. Neural Network approach was used to calculate the risk of resistance evolution on the base of the predictors. Neural Network was able to predict the evolution of resistance in 70% of municipalities when all 6 resistant weeds were considered in the analyses, 30% when Echinochloa spp. alone was considered, losing part of its predictive power maybe due to the smaller quantity of resistance cases present in the database. Maps in Qgis were composed to graphically display the diffusion of the three predictors in the area of the study and the risk of resistance evolution. A resistance screening was performed on 20 randomly collected populations of Echinochloa spp in the area where GIRE had never recorded resistant cases. 16 populations resulted resistant to ALS+ACCase showing that in in these areas resistance is present, but kept at an acceptable level for the farmers. The second part of the research was focused on the recognition of Echinochloa species, matching already published dichotomical keys, with molecular discrimination performed through DNA barcoding approach. Forty accessions of Echinochloa spp. were collected in 2015 from single plant, they were classified and tested for penoxsulam sensitivity. Among the sensible accessions ten were chosen for reproduction in order to obtain a bigger quantity of seeds for further studies. Penoxsulam screening was repeated on these accessions to confirm sensitivity. Morphological classification and molecular marker discrimination were performed both on original and reproduced accessions, with consistent results. Results show that according to Costea & Tardif (2002) only E. crus-galli and E. oryzicola were present among our accessions, according to Tabacchi et al. (2006) there were E. crus-galli, E. oryzicola and E. phyllopogon. Five DNA regions of the chloroplast were analyzed: matK was able to highlight genetic differences between the “white” species, besides distinguishing E. crus-galli, providing a good, but not complete match with Tabacchi et al. (2006) classification. rbcL region instead, differentiating only E. oryzicola from E. crus-galli provided a 100% match with Costea & Tardif (2002) classification. A Specie-Specific PCR protocol was set up on matK gene to discriminate among the “white” Echinochloa species in a single PCR reaction. Dose response experiment was performed twice on 9 accessions using three different herbicides: cyhalofop – butyl, penoxsulam and florpyrauxifen benzyl, both in greenhouse and in outside conditions: although results were variable, especially in the outside experiment, it was clear that the three herbicides had similar efficacy on all Echinochloa species. Results obtained show that planning herbicides strategies on the base of the Echinochloa spp. present on field could be wrong.La resistenza agli erbicidi è un problema che è cresciuto esponenzialmente negli ultimi 10 anni e riguarda tutte le più importanti colture al mondo. L’Italia è il primo produttore europeo di riso con 230.000 ha localizzati nel nord-ovest della Pianura Padana. Ad oggi 6 infestanti hanno evoluto popolazioni resistenti in riso in Italia, fra queste la più importante è Echinochloa spp. La ricerca si è svolta su due binari paralleli: il primo è uno studio epidemiologico a larga scala sulla principale area riso, il secondo è uno studio sulla classificazione di Echinochloa spp. che comprendente esperimenti di dose risposta su varie specie di Echinochloa spp.agli erbicidi. Obiettivo dello studio epidemiologico era analizzare, a livello comunale, il grado di associazione fra presenza di resistenza e tre importanti predittori agronomici: percentuale di semina in acqua, tessitura del suolo e percentuale di rotazione. Le analisi sono state fatte con più approcci statistici: l’analisi discriminante e la regressione logistica hanno permesso di individuare un alto grado di associazione fra la presenza di resistenza ed i predittori. L’approccio Neural Network ha permesso di calcolare il rischio di evolvere popolazioni resistenti sulla base dei predittori: 70% quando tutte le infestanti resistenti sono state considerate, 30% quando solo i casi di Echinochloa spp. sono stati inclusi, perdendo parte del potere predittivo forse a causa della minore quantità di casi di resistenza inclusi nel database. In Qgis sono state create mappe per illustrare la diffusione dei tre predittori nell’area dello studio e il rischio di evoluzione della resistenza. 20 popolazioni di giavone sono state raccolte nei comuni dove non sono mai stati segnalati casi di resistenza al GIRE ed è stato fatto uno screening. 16 popolazioni sono risultate resistenti ACCase+ALS mostrando che in queste aree la resistenza è presente, ma viene tenuta ad un livello accettabile per gli agricoltori. La seconda parte della ricerca riguardava la classificazione delle diverse specie di giavone, abbinando la classificazione fenotipica alla discriminazione fatta attraverso marcatori molecolari usando il DNA barcoding. 40 accessioni di giavone sono state raccolte da piante singole nel 2015, sono state classificate morfologicamente e testate per la sensibilità al penoxsulam. Fra le piante sensibili, 10 sono state riprodotte per ottenere una quantità maggiore di seme. Lo screening con il penoxsulam è stato ripetuto sulle accessioni riprodotte a confermare la sensibilità. La classificazione morfologica e la discriminazione per marcatori molecolari sono state fatte sia sulle piante originali che sulle riprodotte, dando risultati consistenti: nelle popolazioni riprodotte usando Costea & Tardif (2002) sono presenti solo E. crus-galli ed E. oryzicola, usando Tabacchi et al. (2006) sono presenti E. crus-galli, E. oryzicola ed E. phyllopogon. Sono state analizzate 5 regioni di DNA cloroplastico: matK ha discriminato fra le diverse specie di giavone bianco, oltre a E. crus-galli offrendo un buon match, anche se incompleto, con la classificazione di Tabacchi et al. (2006). Le sequenze di rbcL invece hanno differenziato solo E. oryzicola da E. crus-galli, corrispondendo perfettamente a Costea & Tardif (2002) Un protocollo di PCR specie-specifica è stato impostato su matK gene per discriminare diverse specie di giavoni bianchi in una sola reazione di PCR. Gli esperimenti di dose-risposta sono stati fatti sia in serra che all’aperto su 9 accessioni con 3 erbicidi: cyhalofop – butyl, penoxsulam e florpyrauxifen benzyl: anche se i risultati sono stati variabili, soprattutto nell’esperimento all’aperto, è chiaro che i vari erbicidi hanno efficacia simile su tutte le specie di Echinochloa. I risultati ottenuti dimostrano che pianificare le strategie erbicide sulla base delle diverse specie di Echinochla possa essere erroneo.
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Mesaros, Andrea [Verfasser]. « Activation of Stat3 signaling in AgRP neurons promotes locomotor activity / vorgelegt von Andrea Mesaros ». 2008. http://d-nb.info/989800385/34.
Texte intégralLivres sur le sujet "AgRP neuron"
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IEEE International Workshop on Cellular Neural Networks and Their Applications. (1990 Budapest, Hungary). 1990 IEEE International Workshop on Cellular Neural Networks and Their applications, CNNA-90 : Proceedings : Hotel Agro, Budapest, Hungary, December 16-19, 1990. [New York] : Institute of Electrical and Electronics Engineers, 1990.
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Wójcik-Gładysz, Anna. Ghrelin – hormone with many faces. Central regulation and therapy. The Kielanowski Institute of Animal Physiology and Nutrition, Polish Academy of Sciences, 2020. http://dx.doi.org/10.22358/mono_awg_2020.
Texte intégralRésumé :
Discovered in 1999, ghrelin, is one of the peptides co-creating the hypothalamicgastrointestinal axis, otherwise known as the brain-gut axis. Ghrelin participates in many physiological processes and spectrum of its activity is still being discovered. This 28 amino acid peptide ‒ a product of the ghrl gene, was found in all vertebrates and is synthesized and secreted mainly from enteroendocrine X/A cells located in the gastric mucosa of the stomach. Expression of the ghrelin receptor has been found in many nuclei of the hypothalamus involved in appetite regulation. Therefore it’s presumed that ghrelin is one of the crucial hormones deciphering the energy status required for the maintenance of organism homeostasis. Ghrelin acts as a signal of starvation or energy insufficiency and its level in plasma is reduced after the meal. Neuropeptide Y (NPY) and agouti-related peptide (AgRP; NPY/AgRP) neurons located in the arcuate nucleus (ARC) area are the main target of ghrelin in the hypothalamus. This subpopulation of neurons is indispensable for inducing orexigenic action of ghrelin. Moreover ghrelin acting as a neurohormone, mainly in the hypothalamus area, plays an important role in the regulation of growth and reproduction processes. Indeed, ghrelin action on reproductive processes has been observed in the systemic effects exerted at both hypothalamus-pituitary and gonadal levels. Similarly the GH-releasing ghrelin action was observed both on the hypothalamus level and directly on the somatotrophic cells in the pituitary and this dose-related GH releasing activity was found in in vitro as well as in in vivo experiments. In recent years, numerous studies revealed that ghrelin potentially takes part in the treatment of diseases associated with serious disturbances in the organism energy balance and/or functioning of the gastrointestinal tract. It was underlined that ghrelin may be a hormone with a broad spectrum of therapeutic effect on obesity and anorexia nervosa, as well as may also have protective effect on neurodegenerative diseases, inflammatory disorders or functional changes in the body caused by cancers. In overall, ghrelin treatment has been tested in over 100 preclinical studies with healthy volunteers as well as patients with various types of cancer, eating disorders such as anorexia nervosa and bulimia nervosa. It was observed that ghrelin has an excellent clinical safety profile and emerging side effects occurred only in 3–10% of patients and did not constitute a sufficient premise to discontinue the therapy. In general, it can be concluded that ghrelin may be sufficiently used as a prescription drug.
Chapitres de livres sur le sujet "AgRP neuron"
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Huang, Cong, Huiping Lin et Yuhan Xiao. « AGRP : A Fused Aspect-Graph Neural Network for Rating Prediction ». Dans Neural Information Processing, 597–608. Cham : Springer International Publishing, 2021. http://dx.doi.org/10.1007/978-3-030-92273-3_49.
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Han, Yong, Guobin Xia et Qi Wu. « Functional Interrogation of the AgRP Neural Circuits in Control of Appetite, Body Weight, and Behaviors ». Dans Advances in Experimental Medicine and Biology, 1–16. Singapore : Springer Singapore, 2018. http://dx.doi.org/10.1007/978-981-13-1286-1_1.
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Shamiul Islam, Md, Ummya Habiba, Md Abu Baten, Nazrul Amin, Imrus Salehin et Tasmia Tahmida Jidney. « Hybrid Convolution Neural Network with Transfer Learning Approach for Agro-Crop Leaf Disease Identification ». Dans Lecture Notes on Data Engineering and Communications Technologies, 209–17. Cham : Springer Nature Switzerland, 2023. http://dx.doi.org/10.1007/978-3-031-24475-9_18.
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Hong, Yiling. « Impact of Silver Nanoparticles on Neurodevelopment and Neurodegeneration ». Dans Neurotoxicity - New Advances. IntechOpen, 2022. http://dx.doi.org/10.5772/intechopen.101723.
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Silver nanoparticles (AgNPs) are one of the most highly commercialized nanoparticles, having been used extensively as an antimicrobial agent in cosmetics, textiles, foods, and the treatment of diseases. However, the impact of AgNPs on human mental health has not yet been well characterized. Using the human pluripotent stem cell (hPSC) neuronal differentiation cellular model to assess AgNPs neurotoxicity has several benefits. First, hPSCs neuronal differentiation process can faithfully recapitulate stages of neural development from neuronal progenitors to mature neurons which can provide an excellent platform for neurodevelopment and neurodegeneration toxicity testing. Furthermore, it can limit the amount of animal use for toxicity studies. With this cellular model, we examined citrate-coated AgNPs (AgSCs) and Polyvinylpyrrolidone-coated (AgSP) mediated neurotoxicity. Our results suggested that AgNP induced neurotoxicity exhibited a coating and dose-dependent manner. AgSC had high neurotoxicity compared with AgSP. AgSC significantly up-graduated Metallothionein (1F, 1E, 2A) proteins, a metal-binding protein that plays an essential role in metal homeostasis, heavy metal detoxification, and cellular anti-oxidative defense. Transcriptome analysis indicated that AgSC inhibited neurogenesis and axon guidance, promoted gliogenesis and neuronal apoptosis through oxidative stress. Supplementation with ascorbic acid can act as an antioxidant to attenuate AgNP-mediated neurotoxicity.
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Thiel, D. « AN INTERACTIVE NEURAL NETWORK FOR ANALYSING THE FOOD CONSUMER BEHAVIOUR STABILITY ». Dans Agri-Food Quality II, 40–44. Elsevier, 1999. http://dx.doi.org/10.1533/9781845698140.2.40.
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Naidu, Diwakar, Babita Majhi et Surendra Kumar Chandniha. « Development of Rainfall Prediction Models Using Machine Learning Approaches for Different Agro-Climatic Zones ». Dans Advances in Data Mining and Database Management, 72–94. IGI Global, 2021. http://dx.doi.org/10.4018/978-1-7998-6659-6.ch005.
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This study focuses on modelling the changes in rainfall patterns in different agro-climatic zones due to climate change through statistical downscaling of large-scale climate variables using machine learning approaches. Potential of three machine learning algorithms, multilayer artificial neural network (MLANN), radial basis function neural network (RBFNN), and least square support vector machine (LS-SVM) have been investigated. The large-scale climate variable are obtained from National Centre for Environmental Prediction (NCEP) reanalysis product and used as predictors for model development. Proposed machine learning models are applied to generate projected time series of rainfall for the period 2021-2050 using the Hadley Centre coupled model (HadCM3) B2 emission scenario data as predictors. An increasing trend in anticipated rainfall is observed during 2021-2050 in all the ACZs of Chhattisgarh State. Among the machine learning models, RBFNN found as more feasible technique for modeling of monthly rainfall in this region.
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Suganyadevi, S., D. Shamia, R. Arun Sekar et R. Deepa. « Automated diagnosis of disease in grape leaves using deep neural networks ». Dans Agri 4.0 and the Future of Cyber-Physical Agricultural Systems, 257–77. Elsevier, 2024. http://dx.doi.org/10.1016/b978-0-443-13185-1.00014-9.
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Kambo, Rubi, Jyothi Pillai et Sunita Soni. « ENHANCING AGRICULTURE COMMODITY PRICE FORECASTING : INTEGRATION OF DEEP LEARNING AND SOFT COMPUTING TECHNIQUES FOR ECONOMIC, FARMER, AND INDUSTRY PERSPECTIVES ». Dans Futuristic Trends in Computing Technologies and Data Sciences Volume 3 Book 8, 113–20. Iterative International Publishers, Selfypage Developers Pvt Ltd, 2024. http://dx.doi.org/10.58532/v3bkct8p2ch4.
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Forecasting the price of agriculture commodities such as vegetables, fruits, cereals etc. is important related to economic concerned, farmer perspective, Agriculturist and Industrialist. Price forecasting contributes to agricultural producers and all others agro audiences in making sound choices regarding the mandi price, or the retail cost, for their commodity in addition to what crop is most profitable for cultivation with the goal to earn the greatest returns. The result ultimately boosts the circumstance and income for agricultural producers meanwhile also assisting government officials in arriving at decisions associated with agriculture. In the realm of agriculture, neural network techniques have been employed for short-term as well as long-term price predictions. It's possible to find an extensive amount of information available regarding the prices of commodities, daily price movements, and arrival costs. Upcoming commodity price prediction might gain from the integration of deep learning and soft computing techniques.
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Madhuri J. et Indiramma M. « Big Data Analytics-Based Agro Advisory System for Crop Recommendation Using Spark Platform ». Dans Advances in Business Information Systems and Analytics, 227–47. IGI Global, 2023. http://dx.doi.org/10.4018/978-1-6684-7105-0.ch012.
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The advancements in science and technology have led to the generation of colossal data in the agricultural sector as a result of which has entered the world of big data. Big data analytics is the solution to store and analyze such large amounts of data to improve productivity in agricultural practices. Hence, the purpose of this research work is to develop a big data recommendation framework that enables farmers to choose the right crops considering the location-specific parameters. The location-specific weather parameters, soil parameters crop characteristics, and demand for the agricultural product in the previous years are considered in the work. The proposed recommendation model is based on the Spark framework that accepts the soil data in real-time analyses along with weather and pricing data by applying artificial neural networks and suggesting a suitable crop for the field conditions. The chapter prioritizes developing an application useful for farmers, agriculture officers, and researchers to provide efficient crop recommendations.
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N.S. Sampaio, Pedro, et Carla Brites. « Near-Infrared Spectroscopy and Machine Learning : Analysis and Classification Methods of Rice ». Dans Rice [Working Title]. IntechOpen, 2021. http://dx.doi.org/10.5772/intechopen.99017.
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Nowadays, the conventional biochemical methods used to differentiate and characterize rice types, biochemical properties, authentication, and contamination issues are difficult to implement due to the high cost of reagents, time requirement and environmental issues. Actually, the success of agri-food technology is directly related to the quality of analysis of experimental data acquired by sensors or techniques such as the infrared-spectroscopy. To overcome these technical limitations, a rapid and non-destructive methodology for discrimination and classification of rice has been investigated. Near-infrared spectroscopy is considered as fast, clean, and non-destructive analytical tools and its spectra present significant biomolecular information that must be analysed by sophisticated methodologies. Machine learning plays an important role in the analysis of the spectral data being used several methods such as Partial Least Squares, Principal Component Analysis, Partial Least Squares-Discriminant Analysis, Support Vector Machine, Artificial Neuronal Network, among others which can successfully be applied for food classification and discrimination as well as in terms of authentication and contamination issues. The quality control of rice is extremely important at every stage of production, beginning with estimation of raw agricultural materials and monitoring their quality during storage, estimating food quality during the production process and of the final products as well as the determination of their authenticity and the detection of adulterants.
Actes de conférences sur le sujet "AgRP neuron"
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Ma, Yuyang, Chao Yang, Haixiang Guan, Jingyue Xu et Chuli Hu. « Prediction of Soil Organic Matter in Black Soil Region Based on BP Neural Network with Genetic Algorithm Variable Selection ». Dans 2024 12th International Conference on Agro-Geoinformatics (Agro-Geoinformatics), 1–6. IEEE, 2024. http://dx.doi.org/10.1109/agro-geoinformatics262780.2024.10660717.
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Yalcin, Hulya, et Salar Razavi. « Plant classification using convolutional neural networks ». Dans 2016 5th International Conference on Agro-geoinformatics (Agro-geoinformatics). IEEE, 2016. http://dx.doi.org/10.1109/agro-geoinformatics.2016.7577698.
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Chang, Gray S., Blaine Grover, John T. Maki et Misti A. Lillo. « The Feasibility Study of AGR 7-Position Fuel Testing Assembly in NEFT Position ». Dans Fourth International Topical Meeting on High Temperature Reactor Technology. ASMEDC, 2008. http://dx.doi.org/10.1115/htr2008-58098.
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In order to support the Next Generation Nuclear Plant (NGNP) Program 2018 deployment schedule, the Advanced Gas Reactor (AGR) Fuel Development and Qualification Program must reduce the AGR fuel irradiation testing time in the Advanced Test Reactor (ATR) from approximately 2 1/2 calendar years to 1 1/2 calendar years. The AGR fuel irradiation testing requirements are: (a) burn-up of at least 14% FIMA; (b) Fast neutron fluence (E > 0.18 MeV) – maximum < 5.1 × 1025 n/m2; (c) limit of fission power density is 350 W/cc; and (d) irradiation time < 1 1/2 calendar years. The accelerated testing could be accomplished by utilizing the ATR North East flux trap (NEFT) position, which can provide more control of the thermal neutron flux rate than the ATR B-10 position currently being used for the AGR-1 fuel testing, which is regulated to achieve the fuel temperature and burn-up rate requirements. In addition, the Fast (E > 1.0 MeV) to Thermal (E < 0.625 eV) neutron flux ratio (F/T) for the NEFT is much harder (higher) than the F/T ratio for the B-10 position. Thus, an appropriate configuration of Beryllium (Be) and water will need to be determined in order to soften (lower) the F/T ratio to the desired value. The proposed AGR 7-position fuel test configuration in the NEFT will utilize a graphite holder consisting of six fuel specimen positions arranged around the perimeter of the graphite holder with a seventh fuel specimen position in the center of the holder. To soften the neutron spectrum in the fuel compacts, the water volume in the outer water annulus can be increased. To reduce the compact power density, a hafnium filter could be incorporated around the graphite holder. After several trials, a hafnium filter with a thickness of 0.008 inches appeared to adequately reduce the power density to achieve the fuel testing requirements. It was also determined that the chosen beryllium-tube and water annulus configuration would adequately soften the neutron spectrum to achieve the fuel testing requirement. This neutronics study is based upon typical ATR cycle operation of 50 effective full power days (EFPD) per cycle for seven proposed irradiation cycles, and a NE lobe power of the 14 MW. The MCWO-calculated fuel compact power density, burnup (% FIMA), and fast neutron fluence (E > 0.18 MeV) results indicate that the average fuel compact burnup and fast neutron fluence reach 14.79% FIMA and 4.16 × 1025 n/m2, respectively. The fuel compact peak burnup reached 16.68% FIMA with corresponding fast neutron fluence for that fuel compact of 5.06 × 1025 n/m2, which satisfied the fuel testing requirements. It is therefore concluded that accelerating the AGR fuel testing using the proposed AGR 7-position fuel test configuration in the NEFT is very feasible.
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Leng, Chuang, Shanzhen Yi et Wenhao Xie. « Estimation of rainfall based on MODIS using neural networks ». Dans 2019 8th International Conference on Agro-Geoinformatics (Agro-Geoinformatics). IEEE, 2019. http://dx.doi.org/10.1109/agro-geoinformatics.2019.8820239.
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Kulaglic, Ajla, et B. Berk Ustundag. « Neural network with wavelet preprocessing for wheat growth stage estimation ». Dans 2016 5th International Conference on Agro-geoinformatics (Agro-geoinformatics). IEEE, 2016. http://dx.doi.org/10.1109/agro-geoinformatics.2016.7577618.
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Askanian, Haroutioun, Ottavio Novello, Christian Coelho, Sophie Commereuc et Vincent Verney. « Application of agro-wastes for bio-composite materials ». Dans THE SECOND ICRANET CÉSAR LATTES MEETING : Supernovae, Neutron Stars and Black Holes. AIP Publishing LLC, 2015. http://dx.doi.org/10.1063/1.4937321.
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Hawkes, Grant L., James W. Sterbentz et John T. Maki. « Thermal Predictions of the AGR-3/4 Experiment With Time Varying Gas Gaps ». Dans ASME 2014 International Mechanical Engineering Congress and Exposition. American Society of Mechanical Engineers, 2014. http://dx.doi.org/10.1115/imece2014-36943.
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A thermal analysis was performed for the Advanced Gas Reactor test experiment (AGR-3/4) with time varying gas gaps. The experiment was irradiated at the Advanced Test Reactor (ATR) at the Idaho National Laboratory (INL). Several fuel irradiation experiments are planned for the AGR Fuel Development and Qualification Program which supports the development of the Very-High-Temperature gas-cooled Reactor (VHTR) under the Next-Generation Nuclear Plant (NGNP) project. AGR-3/4 combines two tests in a series of planned AGR experiments to test tri-structural-isotropic (TRISO)-coated, low-enriched uranium oxy-carbide fuel. The AGR-3/4 test was designed primarily to assess fission product transport through various graphite materials. The AGR-3/4 test irradiation in the ATR started in December 2011 and finished in April 2014. Forty-eight (48) TRISO fueled compacts were inserted into twelve separate capsules for the experiment (four compacts per capsule). The purpose of this analysis was to calculate the temperatures of each compact and graphite layer to obtain daily average temperatures using time (fast neutron fluence) varying gas gaps and to compare with experimentally measured thermocouple data. Previous experimental data was used for the graphite shrinkage versus fast neutron fluence. Heat rates were input from a detailed physics analysis using the Monte Carlo N-Particle (MCNP) code for each day during the experiment. Individual heat rates for each non-fuel component were input as well. A steady-state thermal analysis was performed for each daily calculation. A finite element model was created for each capsule using the commercial finite element heat transfer and stress analysis package ABAQUS. The fission and neutron gamma heat rates were calculated with the nuclear physics code MCNP. ATR outer shim control cylinders and neck shim rods along with driver fuel power and fuel depletion were incorporated into the daily physics heat rate calculations. Compact and graphite thermal conductivity were input as a function of temperature and neutron fluence with the field variable option in ABAQUS. Surface-to-surface radiation heat transfer along with conduction heat transfer through the gas mixture of helium-neon (used for temperature control) was used in these models. Model results are compared to thermocouple data taken during the experiment.
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Kouhalvandi, Lida, Ece Olcay Gunes et Serdar Ozoguz. « Algorithms for Speeding-Up the Deep Neural Networks For Detecting Plant Disease ». Dans 2019 8th International Conference on Agro-Geoinformatics (Agro-Geoinformatics). IEEE, 2019. http://dx.doi.org/10.1109/agro-geoinformatics.2019.8820541.
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Kang, Lingjun, Liping Di, Meixia Deng, Eugene Yu et Yang Xu. « Forecasting vegetation index based on vegetation-meteorological factor interactions with artificial neural network ». Dans 2016 5th International Conference on Agro-geoinformatics (Agro-geoinformatics). IEEE, 2016. http://dx.doi.org/10.1109/agro-geoinformatics.2016.7577673.
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Sawant, Suryakant, Rishabh Agarwal, Jayantrao Mohite, Ankur Pandit et Srinivasu Pappula. « Field Boundary Identification using Convolutional Neural Network and GIS on High Resolution Satellite Observations ». Dans 2021 9th International Conference on Agro-Geoinformatics (Agro-Geoinformatics). IEEE, 2021. http://dx.doi.org/10.1109/agro-geoinformatics50104.2021.9530340.
Texte intégralRapports d'organisations sur le sujet "AgRP neuron"
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Gothilf, Yoav, Roger Cone, Berta Levavi-Sivan et Sheenan Harpaz. Genetic manipulations of MC4R for increased growth and feed efficiency in fish. United States Department of Agriculture, janvier 2016. http://dx.doi.org/10.32747/2016.7600043.bard.
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The hypothalamic melanocortin system plays a central role in the regulation of food consumption and energy homeostasis in mammals. Accordingly, our working hypothesis in this project was that genetic editing of the mc4r gene, encoding Melanocortin Receptor 4 (MC4R), will enhance food consumption, feed efficiency and growth in fish. To test this hypothesis and to assess the utility of mc4r editing for the enhancement of feed efficiency and growth in fish, the following objectives were set: Test the effect of the mc4r-null allele on feeding behavior, growth, metabolism and survival in zebrafish. Generate mc4r-null alleles in tilapia and examine the consequences for growth and survival, feed efficiency and body composition. Generate and examine the effect of naturally-occurring mc4r alleles found in swordfish on feeding behavior, growth and survival in zebrafish. Define the MC4R-mediated and MC4R-independent effects of AgRP by crossing mc4r- null strains with fish lacking AgRP neurons or the agrpgene. Our results in zebrafish did not support our hypothesis. While knockout of the agrpgene or genetic ablation of hypothalamic AgRP neurons led to reduced food intake in zebrafish larvae, knockout (KO) of the mc4r gene not only did not increase the rate of food intake but even reduced it. Since Melanocortin Receptor 3 (MC3R) has also been proposed to be involved in hypothalamic control of food intake, we also tested the effectofmc3r gene KO. Again, contrary to our hypothesis, the rate of food intake decreased. The next step was to generate a double mutant lucking both functional MC3R and MC4R. Again, the double KO exhibited reduced food intake. Thus, the only manipulation within the melanocortin system that affected food intake in consistent with the expected role of the system was seen in zebrafish larvae upon agrpKO. Interestingly, despite the apparent reduced food intake in the larval stage, these fish grow to be of the same size as wildtype fish at the adult stage. Altogether, it seems that there is a compensatory mechanism that overrides the effect of genetic manipulations of the melanocortin system in zebrafish. Under Aim 3, we introduced the Xna1, XnB1l, and XnB2A mutations from the Xiphophorus MC4R alleles into the zebrafish MC4R gene. We hypothesized that these MC4R mutations would act as dominant negative alleles to increase growth by suppressing endogenous MC4R activity. When we examined the activity of the three mutant alleles, we were unable to document any inhibition of a co-transfected wild type MC4R allele, hence we did not introduce these alleles into zebrafish. Since teleost fish possess two agrpgenes we also tested the effect of KO of the agrp2 gene and ablation of the AgRP2 cells. We found that the AgRP2 system does not affect food consumption but may rather be involved in modulating the stress response. To try to apply genetic editing in farmed fish species we turned to tilapia. Injection of exogenous AgRP in adult tilapia induced significant changes in the expression of pituitary hormones. Genetic editing in tilapia is far more complicated than in zebrafish. Nevertheless, we managed to generate one mutant fish carrying a mutation in mc4r. That individual died before reaching sexual maturity. Thus, our attempt to generate an mc4r-mutant tilapia line was almost successful and indicate out non-obvious capability to generate mutant tilapia.
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Walker, Billy, et Michael Reichenberger. MEASURED THERMAL AND FAST NEUTRON FLUENCE RATES ATR CYCLES 167A AGR. Office of Scientific and Technical Information (OSTI), juillet 2020. http://dx.doi.org/10.2172/1688702.
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Walker, Billy, et Michael Reichenberger. MEASURED THERMAL AND FAST NEUTRON FLUENCE RATES ATR CYCLES 168A AGR. Office of Scientific and Technical Information (OSTI), décembre 2020. http://dx.doi.org/10.2172/2376855.
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Smith, Larry, et Michael Reichenberger. MEASURED THERMAL AND FAST NEUTRON FLUENCE RATES FOR AGR HOLDERS DURING CYCLE 166B. Office of Scientific and Technical Information (OSTI), mars 2020. http://dx.doi.org/10.2172/2370096.
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