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Engel JA, Pålsson E, Vallöf D, Jerlhag E. Ghrelin activates the mesolimbic dopamine system via nitric oxide associated mechanisms in the ventral tegmental area. Nitric Oxide 2023; 131:1-7. [PMID: 36513266 DOI: 10.1016/j.niox.2022.12.001] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/02/2022] [Revised: 11/08/2022] [Accepted: 12/05/2022] [Indexed: 12/14/2022]
Abstract
Besides enhanced feeding, the orexigenic peptide ghrelin activates the mesolimbic dopamine system to cause reward as measured by locomotor stimulation, dopamine release in nucleus accumbens shell (NAcS), and conditioned place preference. Although the ventral tegmental area (VTA) appears to be a central brain region for this ghrelin-reward, the underlying mechanisms within this area are unknown. The findings that the gaseous neurotransmitter nitric oxide (NO) modulate the ghrelin enhanced feeding, led us to hypothesize that ghrelin increases NO levels in the VTA, and thereby stimulates reward-related behaviors. We initially demonstrated that inhibition of NO synthesis blocked the ghrelin-induced activation of the mesolimbic dopamine system. We then established that antagonism of downstream signaling of NO in the VTA, namely sGC, prevents the ability of ghrelin to stimulate the mesolimbic dopamine system. The association of ghrelin to NO was further strengthened by in vivo electrochemical recordings showing that ghrelin enhances the NO release in the VTA. Besides a GABAB -receptor agonist, known to reduce NO and cGMP, blocks the stimulatory properties of ghrelin. The present series of experiments reveal that ablated NO signaling, through pharmacologically inhibiting the production of NO and/or cGMP, prevents the ability of ghrelin to induced reward-related behaviors.
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Affiliation(s)
- Jörgen A Engel
- Institute of Neuroscience and Physiology, Department of Pharmacology, The Sahlgrenska Academy at the University of Gothenburg, Gothenburg, Sweden
| | - Erik Pålsson
- Institute of Neuroscience and Physiology, Department of Neurochemistry and Psychiatry, The Sahlgrenska Academy at the University of Gothenburg, Gothenburg, Sweden
| | - Daniel Vallöf
- Institute of Neuroscience and Physiology, Department of Pharmacology, The Sahlgrenska Academy at the University of Gothenburg, Gothenburg, Sweden
| | - Elisabet Jerlhag
- Institute of Neuroscience and Physiology, Department of Pharmacology, The Sahlgrenska Academy at the University of Gothenburg, Gothenburg, Sweden.
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Hristov M, Landzhov B, Yakimova K. Cafeteria diet-induced obesity reduces leptin-stimulated NADPH-diaphorase reactivity in the hypothalamic arcuate nucleus of rats. Acta Histochem 2020; 122:151616. [PMID: 33066838 DOI: 10.1016/j.acthis.2020.151616] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/27/2020] [Revised: 08/08/2020] [Accepted: 08/17/2020] [Indexed: 02/07/2023]
Abstract
Leptin is an adipokine that plays an important role in the regulation of energy homeostasis. The failure of endogenous and exogenous leptin to mediate its effects (for example, at suppressing appetite and decreasing body weight) has been termed leptin resistance. Hyperleptinemia and leptin resistance can be well demonstrated in animals in which obesity is induced by consumption of a palatable, high-calorie diet (e.g., cafeteria diet-induced obesity). Since leptin receptor signaling is known to be impaired in the hypothalamic arcuate nucleus (ARC) of obese rodents, we investigated the effect of leptin on nicotinamide adenine dinucleotide phosphate-diaphorase (NADPH-d) reactivity in the ARC of male Wistar rats with cafeteria diet-induced obesity. Our results have shown that after intraperitoneal administration of leptin, the number of NADPH-d positive neurons in the ARC was significantly lower in obese rats compared with that observed in normal weight rats. Additionally, we have found that leptin-induced NADPH-d staining in ARC neurons and the adjacent ependyma was decreased in obese rats. The results presented here suggest that the ability of leptin to activate nitric oxide synthase in neurons within the ARC as well as tanycytes and ependymal cells of the third ventricle is reduced in rats made obese by a cafeteria diet. We speculate that impairment in leptin-induced NO production presents a potential mechanism, involved in the pathogenesis of obesity and obesity-related disease states.
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Affiliation(s)
- Milen Hristov
- Department of Pharmacology and Toxicology, Faculty of Medicine, Medical University of Sofia, 2 "Zdrave" St., 1431 Sofia, Bulgaria.
| | - Boycho Landzhov
- Department of Anatomy, Histology and Embryology, Faculty of Medicine, Medical University of Sofia, 2 "Zdrave" St., 1431 Sofia, Bulgaria
| | - Krassimira Yakimova
- Department of Pharmacology and Toxicology, Faculty of Medicine, Medical University of Sofia, 2 "Zdrave" St., 1431 Sofia, Bulgaria
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Nitric oxide and l-arginine regulate feeding in satiated rats. Appetite 2019; 132:44-54. [DOI: 10.1016/j.appet.2018.09.023] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/05/2018] [Revised: 08/14/2018] [Accepted: 09/27/2018] [Indexed: 12/27/2022]
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Zendehdel M, Moosadoost Y, Masoumi R, Rostami B, Shahir MH, Hassanpour S. Endogenous Nitric Oxide and Dopamine Regulate Feeding Behavior in Neonatal Layer-type Chickens. ANNALS OF ANIMAL SCIENCE 2017. [DOI: 10.1515/aoas-2016-0094] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
Abstract
Evidence from animal studies suggests that endogenous nitric oxide and dopamine (DA) have a regulatory role in the rewarding system, but their interaction(s) have not been studied in avian species. In this study, 4 experiments were performed to determine the effects of central administration of L-arginine (nitric oxide precursor; 200 nmol), NG-nitro-L-arginine methyl ester (L-NAME, a nitric oxide synthase inhibitor; 100 nmol), amphetamine (an indirect DA agonist; 125 pmol) and DA (40 pmol) on feeding behavior in neonatal layer-type chickens (each experiment included 4 groups, n=12 birds in each group). Prior to the initiation of the treatments, birds were fasted for 3 hours (FD3). In experiment 1, chickens received intracerebroventricular (ICV) injection of saline, L-NAME (100 nmol), amphetamine (125 pmol), and combination of L-NAME + amphetamine. In experiment 2, chickens received the ICV injection of saline, L-arginine (200 nmol), amphetamine (125 pmol) and their combination. In experiment 3, chickens received ICV injection of saline, L-arginine (200 nmol), DA (40 pmol) and L-arginine + DA. In experiment 4, chickens received ICV injection of saline, L-NAME (100 nmol), DA (40 pmol) and L-NAME + DA. Thereafter, the cumulative food intake (on the basis of metabolic body weight) was recorded until 2-h post injection. The results showed that ICV injection of amphetamine or DA significantly decreased food intake (P<0.05). Also, co-administration of L-NAME + amphetamine attenuated the hypophagic effect of amphetamine (P<0.05), while combined administration of L-NAME and DA had no effect on DA-induced hypophagia. Additionally, the hypophagic effect of amphetamine was significantly amplified by L-arginine (P<0.05), but the combination of L-arginine and DA did not alter feeding behavior which was induced by DA. These results suggest an interaction between DAergic and nitrergic systems via a presynaptic mechanism on food intake regulation in layer-type chicken.
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Affiliation(s)
- Morteza Zendehdel
- Department of Basic Sciences, Faculty of Veterinary Medicine , University of Tehran , 14155-6453 Tehran , Iran (Islamic Republic of)
| | - Yasaman Moosadoost
- Department of Animal Sciences, Faculty of Agriculture , University of Zanjan , 38791-45371 Zanjan , Iran (Islamic Republic of)
| | - Reza Masoumi
- Department of Animal Sciences, Faculty of Agriculture , University of Zanjan , 38791-45371 Zanjan , Iran (Islamic Republic of)
| | - Behnam Rostami
- Department of Animal Sciences, Faculty of Agriculture , University of Zanjan , 38791-45371 Zanjan , Iran (Islamic Republic of)
| | - Mohammad Hossein Shahir
- Department of Animal Sciences, Faculty of Agriculture , University of Zanjan , 38791-45371 Zanjan , Iran (Islamic Republic of)
| | - Shahin Hassanpour
- Department of Basic Sciences, Faculty of Veterinary Medicine, Science and Research Branch , Islamic Azad University , Tehran , Iran (Islamic Republic of)
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Abtahi S, Mirza A, Howell E, Currie PJ. Ghrelin enhances food intake and carbohydrate oxidation in a nitric oxide dependent manner. Gen Comp Endocrinol 2017; 250:9-14. [PMID: 28552460 PMCID: PMC6885356 DOI: 10.1016/j.ygcen.2017.05.017] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/19/2017] [Revised: 05/24/2017] [Accepted: 05/24/2017] [Indexed: 12/13/2022]
Abstract
In the present study we sought to investigate interactions between hypothalamic nitric oxide (NO) and ghrelin signaling on food intake and energy substrate utilization as measured by the respiratory exchange ratio (RER). Guide cannulae were unilaterally implanted in either the arcuate (ArcN) or paraventricular (PVN) nuclei of male Sprague-Dawley rats. Animals were pretreated with subcutaneous (2.5-10mg/kg/ml) or central (0-100pmol) N-nitro-l-Arginine methyl ester (l-NAME) followed by 50pmol of ghrelin administered into either the ArcN or PVN. Both l-NAME and ghrelin were microinjected at the onset of the active cycle and food intake and RER were assessed 2h postinjection. RER was measured as the ratio of the volume of carbon dioxide expelled relative to the volume of oxygen consumed (VCO2/VO2) using an open-circuit indirect calorimeter. Our results demonstrated that peripheral and central l-NAME pretreatment dose-dependently attenuated ghrelin induced increases in food intake and RER in either the ArcN or PVN. In fact the 100pmol dose largely reversed the metabolic effects of ghrelin in both anatomical regions. These findings suggest that ghrelin enhancement of food intake and carbohydrate oxidation in the rat ArcN and PVN is NO-dependent.
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Affiliation(s)
- Shayan Abtahi
- Department of Psychology, Reed College, Portland, OR, USA
| | - Aaisha Mirza
- Department of Psychology, Reed College, Portland, OR, USA
| | - Erin Howell
- Department of Psychology, Reed College, Portland, OR, USA
| | - Paul J Currie
- Department of Psychology, Reed College, Portland, OR, USA.
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Hassanpour S, Zendehdel M, Babapour V, Charkhkar S. Endocannabinoid and nitric oxide interaction mediates food intake in neonatal chicken. Br Poult Sci 2015; 56:443-51. [PMID: 26053311 DOI: 10.1080/00071668.2015.1059407] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
The aim of the current study was to investigate the interaction of the nitric oxide and cannabinoidergic systems on feeding behaviour in neonatal chicken. A total of 6 experiments were designed to evaluate the interaction between cannabinoidergic and nitrergic systems on food intake in 3-h food-deprived (FD3) neonatal chickens. In Experiment 1, chickens received intracerebroventricular (ICV) injections of saline, 2-arachidonoylglycerol (2-AG) (a CB1 receptor agonist, 2 µg), l-arginine (nitric oxide precursor, 200 nmol) and co-administration of 2-AG + l-arginine. In Experiment 2, ICV injection of saline, 2-AG (2 µg), l-NAME (a nitric oxide synthesis inhibitor, 100 nmol) and their combination (2-AG + l-NAME) were applied to the birds. In Experiment 3, injections were saline, CB65 (a CB2 receptor agonist, 1.25 µg), l-arginine (200 nmol) and CB65 + l-arginine. In Experiment 4, birds received ICV injection of saline, CB65 (1.25 µg), l-NAME (100 nmol) and CB65 + l-NAME. In Experiment 5, chickens were ICV injected with saline, l-arginine (800 nmol), SR141716A (a selective CB1 receptor antagonist, 6.25 µg) and l-arginine + SR141716A. In Experiment 6, birds were injected with saline, l-arginine (800 nmol), AM630 (a selective CB2 receptor antagonist, 5 µg) and l-arginine + AM630. Cumulative food intake was recorded until 2-h post injection. ICV injection of CB1 and CB2 receptor agonists increased food intake. Co-injection of 2-AG + l-NAME increased the hyperphagic effects of CB1 receptors. CB2 receptor-induced food intake was not affected by co-administration of CB65 + l-NAME. l-Arginine decreased food intake and this effect was amplified by co-injection of l-arginine + SR141716A. However; CB2 receptor antagonists had no effect on l-arginine-induced hypophagia. The results suggest that there is an interaction between endogenous nitric oxide and the cannabinoidergic system on feeding behaviour which is mediated via CB1 receptors in the neonatal chicken.
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Affiliation(s)
- S Hassanpour
- a Department of Physiology, Faculty of Veterinary Medicine, Science and Research Branch , Islamic Azad University , Tehran , Iran
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Agmatine attenuates lipopolysaccharide induced anorexia and sickness behavior in rats. Pharmacol Biochem Behav 2015; 132:108-114. [DOI: 10.1016/j.pbb.2015.02.013] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/19/2014] [Revised: 02/12/2015] [Accepted: 02/16/2015] [Indexed: 01/14/2023]
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Sapru HN. Role of the hypothalamic arcuate nucleus in cardiovascular regulation. Auton Neurosci 2012; 175:38-50. [PMID: 23260431 DOI: 10.1016/j.autneu.2012.10.016] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2012] [Revised: 10/16/2012] [Accepted: 10/18/2012] [Indexed: 02/07/2023]
Abstract
Recently the hypothalamic arcuate nucleus (Arc) has been implicated in cardiovascular regulation. Both pressor and depressor responses can be elicited by the chemical stimulation of the Arc. The direction of cardiovascular responses (increase or decrease) elicited from the Arc depends on the baseline blood pressure. The pressor responses are mediated via increase in sympathetic nerve activity and involve activation of the spinal ionotropic glutamate receptors. Arc-stimulation elicits tachycardic responses which are mediated via inhibition of vagal input and excitation of sympathetic input to the heart. The pathways within the brain mediating the pressor and tachycardic responses elicited from the Arc have not been delineated. The depressor responses to the Arc-stimulation are mediated via the hypothalamic paraventricular nucleus (PVN). Gamma aminobutyric acid type A receptors, neuropeptide Y1 receptors, and opiate receptors in the PVN mediate the depressor responses elicited from the Arc. Some circulating hormones (e.g., leptin and insulin) may reach the Arc via the leaky blood-brain barrier and elicit their cardiovascular effects. Although the Arc is involved in mediating the cardiovascular responses to intravenously injected angiotensin II and angiotensin-(1-12), these effects may not be due to leakage of these peptides across the blood-brain barrier in the Arc; instead, circulating angiotensins may act on neurons in the SFO and mediate cardiovascular actions via the projections of SFO neurons to the Arc. Cardiovascular responses elicited by acupuncture have been reported to be mediated by direct and indirect projections of the Arc to the RVLM.
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Affiliation(s)
- Hreday N Sapru
- Department of Neurological Surgery, UMDNJ-New Jersey Medical School, 185 South Orange Avenue, Newark, NJ 07103, USA.
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Borner T, Pinkernell S, Lutz TA, Riediger T. Lipopolysaccharide inhibits ghrelin-excited neurons of the arcuate nucleus and reduces food intake via central nitric oxide signaling. Brain Behav Immun 2012; 26:867-79. [PMID: 22465682 DOI: 10.1016/j.bbi.2012.03.005] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/27/2012] [Revised: 03/14/2012] [Accepted: 03/19/2012] [Indexed: 12/30/2022] Open
Abstract
Lipopolysaccharide (LPS) induces anorexia and expression of inducible nitric oxide synthase (iNOS) in the hypothalamic arcuate nucleus (Arc). Peripheral administration of the iNOS inhibitor 1400 W counteracts the anorectic effects of LPS. Here we investigated the role of central NO signaling in LPS anorexia. In electrophysiological studies we tested whether 1400 W counteracts the iNOS-dependent inhibition of Arc neurons triggered by in vivo or in vitro stimulation with LPS. We used the hormone ghrelin as a functional reference stimulus because ghrelin is known to activate orexigenic Arc neurons. Further, we investigated whether in vitro LPS stimulation induces an iNOS-mediated formation of the second messenger cGMP. Since the STAT1 pathway contributes to the regulation of iNOS expression we investigated whether LPS treatment induces STAT1 phosphorylation in the Arc. Finally we tested the effect of intracerebroventricular injection of 1400 W on LPS-induced anorexia. Superfusion with 1400 W (10(-4) M) increased neuronal activity in 37% of neurons in Arc slices from LPS treated (100 μg/kg ip) but not from saline treated rats. Similarly, 1400 W excited 45% of Arc neurons after in vitro stimulation with LPS (100 ng/ml). In both approaches, a considerable percentage of 1400 W sensitive neurons were excited by ghrelin (10(-8)M; 50% and 75%, respectively). In vitro stimulation with LPS induced cGMP formation in the Arc, which was blocked by co-incubation with 1400 W. LPS treatment elicited a pSTAT1 response in the Arc of mice. Central 1400 W injection (4 μg/rat) attenuated LPS-induced anorexia and counteracted the LPS-dependent decrease in respiratory quotient and energy expenditure. In conclusion, the current findings substantiate a role of central iNOS dependent NO formation in LPS-induced effects on eating and energy homeostasis. A pharmacological blockade of NO formation might be a therapeutic approach to ameliorate disease-related anorexia.
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Affiliation(s)
- Tito Borner
- Institute of Veterinary Physiology and Centre of Integrative Human Physiology, University of Zurich, 8057 Zurich, Switzerland
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Shinohara K, Hirooka Y, Kishi T, Sunagawa K. Reduction of Nitric Oxide-Mediated γ-Amino Butyric Acid Release in Rostral Ventrolateral Medulla Is Involved in Superoxide-Induced Sympathoexcitation of Hypertensive Rats. Circ J 2012; 76:2814-21. [DOI: 10.1253/circj.cj-12-0399] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Affiliation(s)
- Keisuke Shinohara
- Department of Cardiovascular Medicine, Kyushu University Graduate School of Medical Sciences
| | - Yoshitaka Hirooka
- Department of Advanced Cardiovascular Regulation and Therapeutics, Kyushu University Graduate School of Medical Sciences
| | - Takuya Kishi
- Department of Advanced Therapeutics for Cardiovascular Diseases, Kyushu University Graduate School of Medical Sciences
| | - Kenji Sunagawa
- Department of Cardiovascular Medicine, Kyushu University Graduate School of Medical Sciences
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Synergic effects of estradiol and progesterone on regulation of the hypothalamic neuronal nitric oxide synthase expression in ovariectomized mice. Brain Res 2011; 1404:1-9. [DOI: 10.1016/j.brainres.2011.06.017] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2011] [Revised: 06/03/2011] [Accepted: 06/04/2011] [Indexed: 11/20/2022]
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Feng DD, Yang SK, Loudes C, Simon A, Al-Sarraf T, Culler M, Alvear-Perez R, Llorens-Cortes C, Chen C, Epelbaum J, Gardette R. Ghrelin and obestatin modulate growth hormone-releasing hormone release and synaptic inputs onto growth hormone-releasing hormone neurons. Eur J Neurosci 2011; 34:732-44. [DOI: 10.1111/j.1460-9568.2011.07787.x] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
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Abstract
This review will summarize recent findings concerning the biological regulation of starvation as it relates to anorexia nervosa (AN), a serious eating disorder that mainly affects female adolescents and young adults. AN is generally viewed as a psychosomatic disorder mediated by obsessive concerns about weight, perfectionism and an overwhelming desire to be thin. By contrast, the thesis that will be developed here is that, AN is primarily a metabolic disorder caused by defective regulation of the starvation response, which leads to ambivalence towards food, decreased food consumption and characteristic psychopathology. We will trace the starvation response from yeast to man and describe the central role of insulin (and insulin-like growth factor-1 (IGF-1))/Akt/ F-box transcription factor (FOXO) signaling in this response. Akt is a serine/threonine kinase downstream of the insulin and IGF-1 receptors, whereas FOXO refers to the subfamily of Forkhead box O transcription factors, which are regulated by Akt. We will also discuss how initial bouts of caloric restriction may alter the production of neurotransmitters that regulate appetite and food-seeking behavior and thus, set in motion a vicious cycle. Finally, an integrated approach to treatment will be outlined that addresses the biological aspects of AN.
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Riediger T, Cordani C, Potes CS, Lutz TA. Involvement of nitric oxide in lipopolysaccharide induced anorexia. Pharmacol Biochem Behav 2010; 97:112-20. [PMID: 20430051 DOI: 10.1016/j.pbb.2010.04.015] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/11/2010] [Revised: 04/01/2010] [Accepted: 04/15/2010] [Indexed: 12/21/2022]
Abstract
Treatment with the bacterial endotoxin lipopolysaccharide (LPS) is a commonly used model to induce disease-related anorexia. Following LPS treatment inducible nitric oxide synthase (iNOS) is expressed in the hypothalamic arcuate nucleus (ARC), where nitric oxide (NO) inhibits orexigenic neurons. Intracellular STAT signaling is triggered by inflammatory stimuli and has been linked to the transcriptional regulation of iNOS. We evaluated whether pharmacological blockade of iNOS by the specific inhibitor 1400W attenuates LPS-induced anorexia. Furthermore, we hypothesized that the tolerance to the anorectic effect occurring after repeated LPS treatment is paralleled by a blunted STAT3 phosphorylation in the ARC. Rats treated with a subcutaneous injection of 1400W (10 mg/kg) showed an attenuated anorectic LPS response relative to control rats receiving only LPS (100 µg/kg; i.p.). Similarly, iNOS blockade attenuated LPS-induced adipsia, hyperthermia, inactivity and the concomitant drop in energy expenditure. While single LPS treatment increased STAT3 phosphorylation in the ARC, rats treated repeatedly with LPS showed no anorectic response and also no STAT3 phosphorylation in the ARC after the second and third LPS injections, respectively. Hence, pSTAT3 signaling in the ARC might be part of the intracellular cascades translating pro-inflammatory stimuli into suppression of food intake. The current findings substantiate a role of iNOS dependent NO formation in disease-related anorexia.
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Affiliation(s)
- Thomas Riediger
- Institute of Veterinary Physiology, University of Zurich, Zurich, Switzerland.
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Riediger T, Eisele N, Scheel C, Lutz TA. Effects of glucagon-like peptide 1 and oxyntomodulin on neuronal activity of ghrelin-sensitive neurons in the hypothalamic arcuate nucleus. Am J Physiol Regul Integr Comp Physiol 2010; 298:R1061-7. [DOI: 10.1152/ajpregu.00438.2009] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Glucagon-like peptide 1 (GLP-1) and oxyntomodulin (OXM) are structurally related gastrointestinal hormones that are secreted in response to food intake. They reduce food intake and body weight and exert partly overlapping actions on glucose homeostasis and gastrointestinal function. The hypothalamic arcuate (ARC) nucleus is among the central structures expressing a high density of GLP-1 receptors (GLP-1R), which are known to be activated by both peptides. It was the aim of our electrophysiological studies to characterize the effects of GLP-1 and OXM on functionally defined ghrelin-sensitive ARC neurons. GLP-1 and OXM (10−7 M) exerted excitatory effects in about two-thirds of ghrelin-inhibited neurons and in approximately one-third of ghrelin-excited cells. In addition, a minor fraction of the ghrelin-excited cells was inhibited by both peptides. There was a high degree of cosensitivity to GLP-1 and OXM, and the effects of both hormones were blocked by the GLP-1R antagonist exendin(9–39). The GLP-1R-mediated excitations and inhibitions persisted under synaptic blockade, indicating a direct postsynaptic mode of action. Our results demonstrate that GLP-1 and OXM directly and similarly alter neuronal activity in the ARC, probably via a common GLP-1R-mediated mechanism. Ghrelin-antagonistic effects on neuronal activity, which might be implicated in ghrelin-antagonistic in vivo actions, resulting from GLP-1R stimulation (e.g., GLP-1R dependent supression of food intake), predominated in ghrelin-inhibited ARC neurons. However, a subset of ghrelin-excited ARC neurons showed responses to OXM or GLP-1, suggesting the existence of a common mode of action for these hormones; the functional relevance of this effect remains to be elucidated.
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Affiliation(s)
- Thomas Riediger
- Institute of Veterinary Physiology and Centre of Integrative Human Physiology, University of Zurich, Zurich, Switzerland
| | - Nicole Eisele
- Institute of Veterinary Physiology and Centre of Integrative Human Physiology, University of Zurich, Zurich, Switzerland
| | - Caroline Scheel
- Institute of Veterinary Physiology and Centre of Integrative Human Physiology, University of Zurich, Zurich, Switzerland
| | - Thomas A. Lutz
- Institute of Veterinary Physiology and Centre of Integrative Human Physiology, University of Zurich, Zurich, Switzerland
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Osterstock G, Escobar P, Mitutsova V, Gouty-Colomer LA, Fontanaud P, Molino F, Fehrentz JA, Carmignac D, Martinez J, Guerineau NC, Robinson ICAF, Mollard P, Méry PF. Ghrelin stimulation of growth hormone-releasing hormone neurons is direct in the arcuate nucleus. PLoS One 2010; 5:e9159. [PMID: 20161791 PMCID: PMC2820089 DOI: 10.1371/journal.pone.0009159] [Citation(s) in RCA: 53] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2009] [Accepted: 01/08/2010] [Indexed: 11/26/2022] Open
Abstract
Background Ghrelin targets the arcuate nucleus, from where growth hormone releasing hormone (GHRH) neurones trigger GH secretion. This hypothalamic nucleus also contains neuropeptide Y (NPY) neurons which play a master role in the effect of ghrelin on feeding. Interestingly, connections between NPY and GHRH neurons have been reported, leading to the hypothesis that the GH axis and the feeding circuits might be co-regulated by ghrelin. Principal Findings Here, we show that ghrelin stimulates the firing rate of identified GHRH neurons, in transgenic GHRH-GFP mice. This stimulation is prevented by growth hormone secretagogue receptor-1 antagonism as well as by U-73122, a phospholipase C inhibitor and by calcium channels blockers. The effect of ghrelin does not require synaptic transmission, as it is not antagonized by γ-aminobutyric acid, glutamate and NPY receptor antagonists. In addition, this hypothalamic effect of ghrelin is independent of somatostatin, the inhibitor of the GH axis, since it is also found in somatostatin knockout mice. Indeed, ghrelin does not modify synaptic currents of GHRH neurons. However, ghrelin exerts a strong and direct depolarizing effect on GHRH neurons, which supports their increased firing rate. Conclusion Thus, GHRH neurons are a specific target for ghrelin within the brain, and not activated secondary to altered activity in feeding circuits. These results support the view that ghrelin related therapeutic approaches could be directed separately towards GH deficiency or feeding disorders.
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Affiliation(s)
- Guillaume Osterstock
- Inserm U-661, Montpellier, France
- CNRS UMR 5203, Institut de Génomique Fonctionnelle, Montpellier, France
- Université Montpellier 1, 2, Montpellier, France
| | - Pauline Escobar
- Inserm U-661, Montpellier, France
- CNRS UMR 5203, Institut de Génomique Fonctionnelle, Montpellier, France
- Université Montpellier 1, 2, Montpellier, France
| | - Violeta Mitutsova
- Inserm U-661, Montpellier, France
- CNRS UMR 5203, Institut de Génomique Fonctionnelle, Montpellier, France
- Université Montpellier 1, 2, Montpellier, France
| | - Laurie-Anne Gouty-Colomer
- Inserm U-661, Montpellier, France
- CNRS UMR 5203, Institut de Génomique Fonctionnelle, Montpellier, France
- Université Montpellier 1, 2, Montpellier, France
| | - Pierre Fontanaud
- Inserm U-661, Montpellier, France
- CNRS UMR 5203, Institut de Génomique Fonctionnelle, Montpellier, France
- Université Montpellier 1, 2, Montpellier, France
| | - François Molino
- Inserm U-661, Montpellier, France
- CNRS UMR 5203, Institut de Génomique Fonctionnelle, Montpellier, France
- Université Montpellier 1, 2, Montpellier, France
| | - Jean-Alain Fehrentz
- Université Montpellier 1, 2, Montpellier, France
- CNRS UMR 5247, Institut des Biomolécules Max Mousseron, Montpellier, France
| | - Danielle Carmignac
- Division of Molecular Neuroendocrinology, MRC National Institute for Medical Research, The Ridgeway, Mill Hill, London, United Kingdom
| | - Jean Martinez
- Université Montpellier 1, 2, Montpellier, France
- CNRS UMR 5247, Institut des Biomolécules Max Mousseron, Montpellier, France
| | - Nathalie C. Guerineau
- Inserm U-661, Montpellier, France
- CNRS UMR 5203, Institut de Génomique Fonctionnelle, Montpellier, France
- Université Montpellier 1, 2, Montpellier, France
| | - Iain C. A. F. Robinson
- Division of Molecular Neuroendocrinology, MRC National Institute for Medical Research, The Ridgeway, Mill Hill, London, United Kingdom
| | - Patrice Mollard
- Inserm U-661, Montpellier, France
- CNRS UMR 5203, Institut de Génomique Fonctionnelle, Montpellier, France
- Université Montpellier 1, 2, Montpellier, France
| | - Pierre-François Méry
- Inserm U-661, Montpellier, France
- CNRS UMR 5203, Institut de Génomique Fonctionnelle, Montpellier, France
- Université Montpellier 1, 2, Montpellier, France
- * E-mail:
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18
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Fioramonti X, Marsollier N, Song Z, Fakira KA, Patel RM, Brown S, Duparc T, Pica-Mendez A, Sanders NM, Knauf C, Valet P, McCrimmon RJ, Beuve A, Magnan C, Routh VH. Ventromedial hypothalamic nitric oxide production is necessary for hypoglycemia detection and counterregulation. Diabetes 2010; 59:519-28. [PMID: 19934009 PMCID: PMC2809968 DOI: 10.2337/db09-0421] [Citation(s) in RCA: 80] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
OBJECTIVE The response of ventromedial hypothalamic (VMH) glucose-inhibited neurons to decreased glucose is impaired under conditions where the counterregulatory response (CRR) to hypoglycemia is impaired (e.g., recurrent hypoglycemia). This suggests a role for glucose-inhibited neurons in the CRR. We recently showed that decreased glucose increases nitric oxide (NO) production in cultured VMH glucose-inhibited neurons. These in vitro data led us to hypothesize that NO release from VMH glucose-inhibited neurons is critical for the CRR. RESEARCH DESIGN AND METHODS The CRR was evaluated in rats and mice in response to acute insulin-induced hypoglycemia and hypoglycemic clamps after modulation of brain NO signaling. The glucose sensitivity of ventromedial nucleus glucose-inhibited neurons was also assessed. RESULTS Hypoglycemia increased hypothalamic constitutive NO synthase (NOS) activity and neuronal NOS (nNOS) but not endothelial NOS (eNOS) phosphorylation in rats. Intracerebroventricular and VMH injection of the nonselective NOS inhibitor N(G)-monomethyl-l-arginine (l-NMMA) slowed the recovery to euglycemia after hypoglycemia. VMH l-NMMA injection also increased the glucose infusion rate (GIR) and decreased epinephrine secretion during hyperinsulinemic/hypoglycemic clamp in rats. The GIR required to maintain the hypoglycemic plateau was higher in nNOS knockout than wild-type or eNOS knockout mice. Finally, VMH glucose-inhibited neurons were virtually absent in nNOS knockout mice. CONCLUSIONS We conclude that VMH NO production is necessary for glucose sensing in glucose-inhibited neurons and full generation of the CRR to hypoglycemia. These data suggest that potentiating NO signaling may improve the defective CRR resulting from recurrent hypoglycemia in patients using intensive insulin therapy.
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Affiliation(s)
- Xavier Fioramonti
- Department of Pharmacology and Physiology, New Jersey Medical School, Newark, New Jersey
| | - Nicolas Marsollier
- National Center for Scientific Research, University Paris Diderot, Paris, France
| | - Zhentao Song
- Department of Pharmacology and Physiology, New Jersey Medical School, Newark, New Jersey
| | - Kurt A. Fakira
- Department of Pharmacology and Physiology, New Jersey Medical School, Newark, New Jersey
| | - Reema M. Patel
- Department of Pharmacology and Physiology, New Jersey Medical School, Newark, New Jersey
| | - Stacey Brown
- Department of Internal Medicine, Yale University School of Medicine, New Haven, Connecticut
| | - Thibaut Duparc
- INSERM U858, Institut de Medecine Moleculaire de Rangueil, IFR150, Université Paul Sabatier, Toulouse, France
| | - Arnaldo Pica-Mendez
- Department of Pharmacology and Physiology, New Jersey Medical School, Newark, New Jersey
| | - Nicole M. Sanders
- Division of Endocrinology/Metabolism, Veterans Affairs Puget Sound Health Care System, Seattle, Washington
| | - Claude Knauf
- INSERM U858, Institut de Medecine Moleculaire de Rangueil, IFR150, Université Paul Sabatier, Toulouse, France
| | - Philippe Valet
- INSERM U858, Institut de Medecine Moleculaire de Rangueil, IFR150, Université Paul Sabatier, Toulouse, France
| | - Rory J. McCrimmon
- INSERM U858, Institut de Medecine Moleculaire de Rangueil, IFR150, Université Paul Sabatier, Toulouse, France
| | - Annie Beuve
- Department of Pharmacology and Physiology, New Jersey Medical School, Newark, New Jersey
| | - Christophe Magnan
- National Center for Scientific Research, University Paris Diderot, Paris, France
| | - Vanessa H. Routh
- Department of Pharmacology and Physiology, New Jersey Medical School, Newark, New Jersey
- Corresponding author: Vanessa H. Routh,
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19
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Nakamura T, Bhatt S, Sapru HN. Cardiovascular responses to hypothalamic arcuate nucleus stimulation in the rat: role of sympathetic and vagal efferents. Hypertension 2009; 54:1369-75. [PMID: 19884562 DOI: 10.1161/hypertensionaha.109.140715] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Experiments were carried out in urethane-anesthetized, artificially ventilated, adult male Wistar rats. Microinjections (50 nL) of N-methyl-d-aspartic acid (1, 5, and 10 mmol/L), but not artificial cerebrospinal fluid, into the hypothalamic arcuate nucleus (ARCN) elicited increases in mean arterial pressure (5.7+/-0.5, 13.2+/-1.4, and 17.3+/-1.1 mm Hg, respectively) and heart rate (24.3+/-4.3, 49.3+/-5.2, and 75.2+/-8.0 bpm, respectively). ARCN stimulation was accomplished by microinjections of a maximally effective concentration of N-methyl-d-aspartic acid (10 mmol/L). The tachycardic responses to the ARCN stimulation were significantly attenuated after bilateral vagotomy. Intrathecal injections of ionotropic glutamate receptor (iGLUR) antagonists completely blocked pressor responses to the ARCN stimulation, whereas the tachycardic responses were significantly attenuated but not abolished. Intrathecal injections of iGLUR antagonists at T9 to T10, combined with bilateral vagotomy, completely blocked the tachycardic responses to ARCN stimulation. ARCN stimulation with N-methyl-d-aspartic acid elicited increased activities of the greater splanchnic nerve (91.7+/-14.8%) and the renal nerve (109.3+/-13%). Intrathecal injections of iGLURs at T9 to T10 blocked the increase in the greater splanchnic nerve activity in response to ARCN stimulation. These results indicate the following: (1) the chemical stimulation of the ARCN elicits increases in mean arterial pressure, greater splanchnic nerve and renal nerve activity, and heart rate; (2) the increases in mean arterial pressure and sympathetic nerve activity are mediated via the activation of spinal cord iGLURs; and (3) the increases in heart rate are mediated via the activation of spinal cord iGLURs and decreases in vagal input to the heart.
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Affiliation(s)
- Takeshi Nakamura
- Department of Neurological Surgery, MSB H-586, UMDNJ-New Jersey Medical School, 185 South Orange Ave, Newark, NJ 07103, USA
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20
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Aslan A, Yildirim M, Ayyildiz M, Güven A, Agar E. The role of nitric oxide in the inhibitory effect of ghrelin against penicillin-induced epileptiform activity in rat. Neuropeptides 2009; 43:295-302. [PMID: 19552953 DOI: 10.1016/j.npep.2009.05.005] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/09/2009] [Revised: 04/10/2009] [Accepted: 05/23/2009] [Indexed: 11/25/2022]
Abstract
Ghrelin, a gastric peptide with key action on food intake, has been recently recognized as a potential antiepileptic agent. In the present study, we investigated the involvement of nitric oxide in the effect of ghrelin on penicillin-induced epileptiform activity in rat. Thirty minutes after penicillin injection, ghrelin, at doses of 0.5, 1, 2 microg, was administered intracerebroventricularly (i.c.v.). Ghrelin, at a dose of 1 microg, significantly decreased the mean frequency of epileptiform activity without changing the amplitude whereas other doses of ghrelin (0.5 and 2 microg) did not alter either the mean of frequency or amplitude of epileptiform activity. The effects of systemic administration of nitric oxide synthase (NOS) inhibitors, non-selective N(G)-nitro-l-arginine methyl ester (l-NAME), selective neuronal NOS inhibitor, 7-nitroindazole (7-NI) and NO substrate, l-arginine on the anticonvulsive effects of ghrelin were investigated. The administration of l-NAME (60 mg/kg, i.p.), 15 min before ghrelin (1microg) application, reversed the anti-epileptiform effects of ghrelin whereas 7-NI (40 mg/kg, i.p.) did not influence it. The present study provides electrophysiological evidence that the intracerebroventricular injection of ghrelin has an inhibitory effect against epileptiform activity in the penicillin model of epilepsy. The anti-epileptiform activity of ghrelin was reversed by nonspecific nitric oxide synthase inhibitor l-NAME, but not selective neuronal nitric oxide synthase inhibitor 7-NI, indicating that ghrelin requires activation of endothelial-NOS/NO route in the brain.
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Affiliation(s)
- Ali Aslan
- Department of Physiology, Faculty of Medicine, University of Ondokuz Mayis, 55139 Samsun, Turkey
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21
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Abstract
As a chemical transmitter in the mammalian central nervous system, nitric oxide (NO) is still thought a bit of an oddity, yet this role extends back to the beginnings of the evolution of the nervous system, predating many of the more familiar neurotransmitters. During the 20 years since it became known, evidence has accumulated for NO subserving an increasing number of functions in the mammalian central nervous system, as anticipated from the wide distribution of its synthetic and signal transduction machinery within it. This review attempts to probe beneath those functions and consider the cellular and molecular mechanisms through which NO evokes short- and long-term modifications in neural performance. With any transmitter, understanding its receptors is vital for decoding the language of communication. The receptor proteins specialised to detect NO are coupled to cGMP formation and provide an astonishing degree of amplification of even brief, low amplitude NO signals. Emphasis is given to the diverse ways in which NO receptor activation initiates changes in neuronal excitability and synaptic strength by acting at pre- and/or postsynaptic locations. Signalling to non-neuronal cells and an unexpected line of communication between endothelial cells and brain cells are also covered. Viewed from a mechanistic perspective, NO conforms to many of the rules governing more conventional neurotransmission, particularly of the metabotropic type, but stands out as being more economical and versatile, attributes that presumably account for its spectacular evolutionary success.
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Affiliation(s)
- John Garthwaite
- Wolfson Institute for Biomedical Research, University College London, Gower Street, London WCIE 6BT, UK.
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22
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Bibliography. Current world literature. Growth and development. Curr Opin Endocrinol Diabetes Obes 2008; 15:79-101. [PMID: 18185067 DOI: 10.1097/med.0b013e3282f4f084] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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23
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Becskei C, Riediger T, Hernádfalvy N, Arsenijevic D, Lutz TA, Langhans W. Inhibitory effects of lipopolysaccharide on hypothalamic nuclei implicated in the control of food intake. Brain Behav Immun 2008; 22:56-64. [PMID: 17624718 DOI: 10.1016/j.bbi.2007.06.002] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/31/2007] [Revised: 06/01/2007] [Accepted: 06/02/2007] [Indexed: 10/23/2022] Open
Abstract
The arcuate nucleus (Arc) and the lateral hypothalamic area (LHA), two key hypothalamic nuclei regulating feeding behavior, express c-Fos, a marker of neuronal activation in fasted animals. This is reversed by refeeding. In the present study we tested whether an anorectic dose of lipopolysaccharide (LPS), the cell wall component of Gram-negative bacteria, also inhibits fasting-induced c-Fos expression in these hypothalamic nuclei. This would suggest that they are involved in anorexia during bacterial infections as well. We also studied whether LPS modulates the activity of orexin-A positive (OX+) LHA neurons. Food deprived BALB/c mice were injected with LPS or saline and were sacrificed 4 or 6h later. Four hours after injection, LPS reduced the number of c-Fos positive cells in the Arc and in the LHA, but had no effect on c-Fos in OX+ neurons. Six hours after injection, LPS reduced c-Fos expression in the LHA, both in the OX- and OX+ neurons, but not in the Arc. These results show that LPS modulates neuronal activity in the Arc and LHA similar to feeding-related stimuli, suggesting that the observed effects might contribute to the anorectic effect of LPS. Thus, physiological satiety signals released during refeeding and anorexia during bacterial infection seem to engage similar neuronal substrates.
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Affiliation(s)
- Csilla Becskei
- Institute of Veterinary Physiology and Zurich Centre of Human Integrative Physiology, University of Zurich, Winterthurerstrasse 260, 8057 Zurich, Switzerland.
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