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Mahmoudi F, Haghighat Gollo K. Influences of Serotonin Hydrochloride on Adiponectin, Ghrelin and KiSS1 Genes Expression. Galen Med J 2021; 9:e1767. [PMID: 34466589 PMCID: PMC8343906 DOI: 10.31661/gmj.v9i0.1767] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/27/2019] [Revised: 12/22/2019] [Accepted: 02/03/2020] [Indexed: 11/16/2022] Open
Abstract
Background:
Serotonin and kisspeptin stimulates gonadotropin-releasing hormone (GnRH) and luteinizing hormone (LH) release while ghrelin and adiponectin inhibit them. In the present experimental study, the effects of central injection of serotonin were investigated on LH concentration, KiSS1, adiponectin, and ghrelin genes expression.
Materials and Methods: Fifteen Wistar male rats in three groups received saline or serotonin hydrochloride via the third cerebral ventricle. Blood samples were collected via the tail vein. Serum LH concentration and relative gene expression were evaluated by radioimmunoassay and real-time polymerase chain reaction method, respectively. Results:
Serotonin significantly increased the mean serum LH concentration and KiSS1 gene expression levels compared to the saline group. Serotonin significantly decreased the mean ghrelin and adiponectin genes expression levels compared to the saline group.
Conclusion: The serotonergic pathway may have stimulatory effects on hypothalamic kisspeptin synthesis, partly via inhibiting hypothalamic ghrelin and adiponectin neural activity.
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Affiliation(s)
- Fariba Mahmoudi
- Faculty of Sciences, University of Mohaghegh Ardabili, Ardabil, Iran
- Correspondence to: Fariba Mahmoudi, Faculty of Physiology, Ph. D. Faculty of Sciences, University of Mohaghegh Ardabili, Ardabil, Iran Telephone Number: 09144190422 Email Address:
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Kumbar J, Ganesh CB. Alpha-melanocyte stimulating hormone immunoreactivity in the brain of the cichlid fish Oreochromis mossambicus. Neuropeptides 2021; 87:102128. [PMID: 33639356 DOI: 10.1016/j.npep.2021.102128] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/06/2021] [Accepted: 02/09/2021] [Indexed: 01/01/2023]
Abstract
This study reports the distribution of a pro-opiomelanocortin-derived neuropeptide α-MSH in the brain of the cichlid fish Oreochromis mossambicus. α-MSH-ir fibres were found in the granule cell layer of the olfactory bulb, the medial olfactory tract, the pallium and the subpallium, whereas in the preoptic area of the telencephalon, few large α-MSH-ir perikarya along with extensively labeled fibres were observed close to the ventricular border. Dense network of α-MSH-ir fibres were seen in the hypothalamic areas such as the nucleus preopticus pars magnocellularis, the nucleus preopticus pars parvocellularis, the suprachiasmatic nucleus, the nucleus anterior tuberis, the paraventricular organ, the subdivisions of the nucleus recessus lateralis and the nucleus recessus posterioris. In the nucleus lateralis pars medialis, some α-MSH-ir perikarya and fibres were found along the ventricular margin. In the diencephalon, numerous α-MSH-ir fibres were detected in the nucleus posterior tuberis, the nucleus of the fasciculus longitudinalis medialis and the nucleus preglomerulosus medialis, whereas in the mesencephalon, α-MSH-ir fibres were located in the optic tectum, the torus semicircularis and the tegmentum. In the rhombencephalon, α-MSH-ir fibres were confined to the medial octavolateralis nucleus and the descending octaval nucleus. In the pituitary gland, densely packed α-MSH-ir cells were observed in the pars intermedia region. The widespread distribution of α-MSH-immunoreactivity throughout the brain and the pituitary gland suggests a role for α-MSH peptide in regulation of several neuroendocrine and sensorimotor functions as well as darkening of pigmentation in the tilapia.
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Affiliation(s)
- Jyoti Kumbar
- Neuroendocrinology Research Laboratory, Department of Studies in Zoology, Karnatak University, Dharwad 580 003, India
| | - C B Ganesh
- Neuroendocrinology Research Laboratory, Department of Studies in Zoology, Karnatak University, Dharwad 580 003, India.
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mTORC1 and CB1 receptor signaling regulate excitatory glutamatergic inputs onto the hypothalamic paraventricular nucleus in response to energy availability. Mol Metab 2019; 28:151-159. [PMID: 31420305 PMCID: PMC6822143 DOI: 10.1016/j.molmet.2019.08.005] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/01/2019] [Revised: 07/31/2019] [Accepted: 08/02/2019] [Indexed: 12/29/2022] Open
Abstract
OBJECTIVE The hypothalamic paraventricular nucleus (PVN) is a key target of the melanocortin system, which orchestrates behavioral and metabolic responses depending on energy availability. The mechanistic target of rapamycin complex 1 (mTORC1) and the endocannabinoid type 1 receptor (CB1R) pathways are two key signaling systems involved in the regulation of energy balance whose activity closely depends upon energy availability. Here we tested the hypothesis that modulation of mTORC1 and CB1R signaling regulates excitatory glutamatergic inputs onto the PVN. METHODS Patch-clamp recordings in C57BL/6J mice, in mice lacking the mTORC1 component Rptor or CB1R in pro-opio-melanocortin (POMC) neurons, combined with pharmacology targeting mTORC1, the melanocortin receptor type 4 (MC4R), or the endocannabinoid system under chow or a hypercaloric diet. RESULTS Acute pharmacological inhibition of mTORC1 in C57BL/6J mice decreased glutamatergic inputs onto the PVN via a mechanism requiring modulation of MC4R, endocannabinoid 2-AG mobilization by PVN parvocellular neurons, and retrograde activation of presynaptic CB1R. Further electrophysiology studies using mice lacking mTORC1 activity or CB1R in POMC neurons indicated that the observed effects involved mTORC1 and CB1R-dependent regulation of glutamate release from POMC neurons. Finally, energy surfeit caused by hypercaloric high-fat diet feeding, rapidly and time-dependently altered the glutamatergic inputs onto parvocellular neurons and the ability of mTORC1 and CB1R signaling to modulate such excitatory activity. CONCLUSIONS These findings pinpoint the relationship between mTORC1 and endocannabinoid-CB1R signaling in the regulation of the POMC-mediated glutamatergic inputs onto PVN parvocellular neurons and its rapid alteration in conditions favoring the development of obesity.
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Dos-Santos RC, Reis LC, Perello M, Ferguson AV, Mecawi AS. The actions of ghrelin in the paraventricular nucleus: energy balance and neuroendocrine implications. Ann N Y Acad Sci 2019; 1455:81-97. [PMID: 31008525 DOI: 10.1111/nyas.14087] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2018] [Revised: 02/28/2019] [Accepted: 03/10/2019] [Indexed: 12/15/2022]
Abstract
Ghrelin is a peptide mainly produced and secreted by the stomach. Since its discovery, the impact of ghrelin on the regulation of food intake has been the most studied function of this hormone; however, ghrelin affects a wide range of physiological systems, many of which are controlled by the hypothalamic paraventricular nucleus (PVN). Several pathways may mediate the effects of ghrelin on PVN neurons, such as direct or indirect effects mediated by circumventricular organs and/or the arcuate nucleus. The ghrelin receptor is expressed in PVN neurons, and the peripheral or intracerebroventricular administration of ghrelin affects PVN neuronal activity. Intra-PVN application of ghrelin increases food intake and decreases fat oxidation, which chronically contribute to the increased adiposity. Additionally, ghrelin modulates the neuroendocrine axes controlled by the PVN, increasing the release of vasopressin and oxytocin by magnocellular neurons and corticotropin-releasing hormone by neuroendocrine parvocellular neurons, while possibly inhibiting the release of thyrotropin-releasing hormone. Thus, the PVN is an important target for the actions of ghrelin. Our review discusses the mechanisms of ghrelin actions in the PVN, and its potential implications for energy balance, neuroendocrine, and integrative physiological control.
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Affiliation(s)
- Raoni C Dos-Santos
- Department of Physiological Sciences, Federal Rural University of Rio de Janeiro, Seropédica, Brazil
| | - Luís C Reis
- Department of Physiological Sciences, Federal Rural University of Rio de Janeiro, Seropédica, Brazil
| | - Mario Perello
- Laboratory of Neurophysiology, Multidisciplinary Institute of Cell Biology, La Plata, Argentina
| | - Alastair V Ferguson
- Centre for Neuroscience Studies, Queen's University, Kingston, Ontario, Canada
| | - André S Mecawi
- Laboratory of Neuroendocrinology, Department of Biophysics, Paulista Medical School, Federal University of São Paulo, São Paulo, Brazil
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Chen C, Wang H, Jiao H, Wang X, Zhao J, Lin H. Feed habituation alleviates decreased feed intake after feed replacement in broilers. Poult Sci 2018; 97:733-742. [DOI: 10.3382/ps/pex358] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2017] [Accepted: 10/30/2017] [Indexed: 11/20/2022] Open
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Abstract
Obesity, a major risk factor for the development of diabetes mellitus, cardiovascular diseases and certain types of cancer, arises from a chronic positive energy balance that is often due to unlimited access to food and an increasingly sedentary lifestyle on the background of a genetic and epigenetic vulnerability. Our understanding of the humoral and neuronal systems that mediate the control of energy homeostasis has improved dramatically in the past few decades. However, our ability to develop effective strategies to slow the current epidemic of obesity has been hampered, largely owing to the limited knowledge of the mechanisms underlying resistance to the action of metabolic hormones such as leptin and ghrelin. The development of resistance to leptin and ghrelin, hormones that are crucial for the neuroendocrine control of energy homeostasis, is a hallmark of obesity. Intensive research over the past several years has yielded tremendous progress in our understanding of the cellular pathways that disrupt the action of leptin and ghrelin. In this Review, we discuss the molecular mechanisms underpinning resistance to leptin and ghrelin and how they can be exploited as targets for pharmacological management of obesity.
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Affiliation(s)
- Huxing Cui
- Department of Pharmacology, University of Iowa, Iowa City, Iowa 52246, USA
- Fraternal Order of Eagles Diabetes Research Center, University of Iowa, Iowa City, Iowa 52242, USA
| | - Miguel López
- Department of Physiology, Center for Research in Molecular Medicine and Chronic Diseases (CiMUS), University of Santiago de Compostela-Instituto de Investigación Sanitaria, Santiago de Compostela 15782, Spain
- Centro de Investigación Biomédica en Red-Fisiopatología de la Obesidad y Nutrición (CIBERobn), Santiago de Compostela 15706, Spain
| | - Kamal Rahmouni
- Department of Pharmacology, University of Iowa, Iowa City, Iowa 52246, USA
- Fraternal Order of Eagles Diabetes Research Center, University of Iowa, Iowa City, Iowa 52242, USA
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Lucas N, Legrand R, Breton J, Déchelotte P, Edwards-Lévy F, Fetissov SO. Chronic delivery of α-melanocyte-stimulating hormone in rat hypothalamus using albumin-alginate microparticles: effects on food intake and body weight. Neuroscience 2015; 290:445-53. [PMID: 25637491 DOI: 10.1016/j.neuroscience.2015.01.037] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2014] [Revised: 01/08/2015] [Accepted: 01/08/2015] [Indexed: 02/08/2023]
Abstract
Chronic delivery of neuropeptides in the brain is a useful experimental approach to study their long-term effects on various biological parameters. In this work, we tested albumin-alginate microparticles, as a potential delivery system, to study if continuous release in the hypothalamus of α-melanocyte-stimulating hormone (α-MSH), an anorexigenic neuropeptide, may result in a long-term decrease in food intake and body weight. The 2-week release of α-MSH from peptide-loaded particles was confirmed by an in vitro assay. Then, daily food intake and body weight were studied for 18 days in rats injected bilaterally into the paraventricular hypothalamic nucleus with particles loaded or not with α-MSH. A decrease in body weight gain, persisting throughout the study, was found in rats injected with α-MSH-charged particles as compared with rats receiving non-charged particles and with rats injected with the same dose of α-MSH in solution. Food intake was significantly decreased for 3 days in rats receiving α-MSH-loaded particles and it was not followed by the feeding rebound effect which appears after food restriction. The presence of α-MSH-loaded particles in the hypothalamus was confirmed by immunohistochemistry. In conclusion, our study validates albumin-alginate microparticles as a new carrier system for long-term delivery of neuropeptides in the brain and demonstrates that chronic delivery of α-MSH in the hypothalamus results in a prolonged suppression of food intake and a decrease of body weight gain in rats.
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Affiliation(s)
- N Lucas
- Inserm UMR1073, Nutrition, Gut and Brain Laboratory, Rouen 76183, France; Institute for Research and Innovation in Biomedicine (IRIB), Rouen University, Normandy University, 76000, France
| | - R Legrand
- Inserm UMR1073, Nutrition, Gut and Brain Laboratory, Rouen 76183, France; Institute for Research and Innovation in Biomedicine (IRIB), Rouen University, Normandy University, 76000, France
| | - J Breton
- Inserm UMR1073, Nutrition, Gut and Brain Laboratory, Rouen 76183, France; Institute for Research and Innovation in Biomedicine (IRIB), Rouen University, Normandy University, 76000, France
| | - P Déchelotte
- Inserm UMR1073, Nutrition, Gut and Brain Laboratory, Rouen 76183, France; Institute for Research and Innovation in Biomedicine (IRIB), Rouen University, Normandy University, 76000, France; Rouen University Hospital, CHU Charles Nicolle, Rouen 76183, France
| | - F Edwards-Lévy
- Institute of Molecular Chemistry of Reims (ICMR), UMR CNRS 7312, University of Reims Champagne-Ardenne, 51100, France
| | - S O Fetissov
- Inserm UMR1073, Nutrition, Gut and Brain Laboratory, Rouen 76183, France; Institute for Research and Innovation in Biomedicine (IRIB), Rouen University, Normandy University, 76000, France.
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Byerly MS, Swanson RD, Semsarzadeh NN, McCulloh PS, Kwon K, Aja S, Moran TH, Wong GW, Blackshaw S. Identification of hypothalamic neuron-derived neurotrophic factor as a novel factor modulating appetite. Am J Physiol Regul Integr Comp Physiol 2013; 304:R1085-95. [PMID: 23576617 DOI: 10.1152/ajpregu.00368.2012] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Disruption of finely coordinated neuropeptide signals in the hypothalamus can result in altered food intake and body weight. We identified neuron-derived neurotrophic factor (NENF) as a novel secreted protein through a large-scale screen aimed at identifying novel secreted hypothalamic proteins that regulate food intake. We observed robust Nenf expression in hypothalamic nuclei known to regulate food intake, and its expression was altered under the diet-induced obese (DIO) condition relative to the fed state. Hypothalamic Nenf mRNA was regulated by brain-derived neurotrophic factor (BDNF) signaling, itself an important regulator of appetite. Delivery of purified recombinant BDNF into the lateral cerebral ventricle decreased hypothalamic Nenf expression, while pharmacological inhibition of trkB signaling increased Nenf mRNA expression. Furthermore, recombinant NENF administered via an intracerebroventricular cannula decreased food intake and body weight and increased hypothalamic Pomc and Mc4r mRNA expression. Importantly, the appetite-suppressing effect of NENF was abrogated in obese mice fed a high-fat diet, demonstrating a diet-dependent modulation of NENF function. We propose the existence of a regulatory circuit involving BDNF, NENF, and melanocortin signaling. Our study validates the power of using an integrated experimental and bioinformatic approach to identify novel CNS-derived proteins with appetite-modulating function and reveals NENF as an important central modulator of food intake.
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Affiliation(s)
- Mardi S Byerly
- Department of Physiology and Center for Metabolism and Obesity Research, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA.
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Liu L, Song Z, Sheikhahmadi A, Jiao H, Lin H. Effect of corticosterone on gene expression of feed intake regulatory peptides in laying hens. Comp Biochem Physiol B Biochem Mol Biol 2012; 162:81-7. [PMID: 22554475 DOI: 10.1016/j.cbpb.2012.04.005] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/27/2011] [Revised: 04/06/2012] [Accepted: 04/10/2012] [Indexed: 11/16/2022]
Abstract
The present study was conducted to explore the effects of corticosterone (CORT) on the regulation of appetite-associated genes in laying hens. Forty eight laying hens were randomly divided into two groups: one received subcutaneous injection of CORT (2mg/kg body weight, CORT-exposed) and the other received sham-treatment (Control). Treatment of hens with CORT stimulated an increase (P<0.05) in plasma CORT, glucose, uric acid (UA), insulin, cholesterol (Chol) and triiodothyronine (T(3)), but the concentrations of plasma non-esterified fatty acids (NEFA) and triacylglycerol (TG) were decreased (P<0.05). CORT treatment had no significant effect (P>0.05) on the mRNA levels of neuropeptide Y (NPY), corticotropin-releasing hormone (CRH), melanocortin receptor 4 and 5 (MCR-4 and MCR-5) and cholecystokinin (CCK) in the hypothalamus when compared with control hens. However, the expression of pro-opiomelanocortin (POMC), agouti-related protein (AgRP) and melanocortin recepter 1 (MCR-1) were significantly (P<0.05) suppressed while the mRNA levels of ghrelin and cocaine-and amphetamine-regulated transcript (CART) were significantly upregulated (P<0.05) in CORT-treated hens. Treatment of laying hens with CORT had no significant (P>0.05) effect on the mRNA levels of CCK in the glandular stomach and the duodenum, and those of ghrelin in the glandular stomach, the duodenum and the jejunum. However, the mRNA levels of CCK in the jejunum and the ileum, and those of ghrelin in the ileum were significantly (P<0.05) suppressed by CORT treatment. In conclusion, these results suggest that CORT plays a unique role in some special neuropeptides (e.g., ghrelin, CART, POMC, CCK and MCRs) and a dynamic balance between these appetite-associated peptides in the hypothalamus and the gastrointestinal tract defines the feeding status of CORT-exposed laying hens.
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Affiliation(s)
- Lei Liu
- Department of Animal Science, Shandong Agricultural University, Taian, Shandong 271018, China
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Cardona Cano S, Merkestein M, Skibicka KP, Dickson SL, Adan RAH. Role of ghrelin in the pathophysiology of eating disorders: implications for pharmacotherapy. CNS Drugs 2012; 26:281-96. [PMID: 22452525 DOI: 10.2165/11599890-000000000-00000] [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] [Indexed: 12/23/2022]
Abstract
Ghrelin is the only known circulating orexigenic hormone. It increases food intake by interacting with hypothalamic and brainstem circuits involved in energy balance, as well as reward-related brain areas. A heightened gut-brain ghrelin axis is an emerging feature of certain eating disorders such as anorexia nervosa and Prader-Willi syndrome. In common obesity, ghrelin levels are lowered, whereas post-meal ghrelin levels remain higher than in lean individuals. Agents that interfere with ghrelin signalling have therapeutic potential for eating disorders, including obesity. However, most of these drugs are only in the preclinical phase of development. Data obtained so far suggest that ghrelin agonists may have potential in the treatment of anorexia nervosa, while ghrelin antagonists seem promising for other eating disorders such as obesity and Prader-Willi syndrome. However, large clinical trials are needed to evaluate the efficacy and safety of these drugs.
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Shariat-Madar B, Kolte D, Verlangieri A, Shariat-Madar Z. Prolylcarboxypeptidase (PRCP) as a new target for obesity treatment. Diabetes Metab Syndr Obes 2010; 3:67-78. [PMID: 20694162 PMCID: PMC2916657 DOI: 10.2147/dmsott.s7290] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/03/2022] Open
Abstract
Recently, we serendipitously discovered that mice with the deficiency of the enzyme prolylcarboxypeptidase (PRCP) have elevated alpha-melanocyte-stimulating hormone (alpha-MSH) levels which lead to decreased food intake and weight loss. This suggests that PRCP is an endogenous inactivator of alpha-MSH and an appetite stimulant. Since a modest weight loss can have the most profound influence on reducing cardiovascular risk factors, the inhibitors of PRCP would be emerging as a possible alternative for pharmacotherapy in high-risk patients with obesity and obesity-related disorders. The discovery of a new biological activity of PRCP in the PRCP-deficient mice and studies of alpha-MSH function indicate the importance and complexity of the hypothalamic pro-opiomelanocortin (POMC) system in altering food intake. Identifying a role for PRCP in regulating alpha-MSH in the brain may be a critical step in enhancing our understanding of how the brain controls food intake and body weight. In light of recent findings, the potential role of PRCP in regulating fuel homeostasis is critically evaluated. Further studies of the role of PRCP in obesity are much needed.
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Affiliation(s)
- B Shariat-Madar
- College of Literature, Science, and the Arts, University of Michigan, Ann Arbor MI, USA
| | - D Kolte
- School of Pharmacy, Department of Pharmacology, University of Mississippi, University, MS, USA
| | - A Verlangieri
- School of Pharmacy, Department of Pharmacology, University of Mississippi, University, MS, USA
| | - Z Shariat-Madar
- School of Pharmacy, Department of Pharmacology, University of Mississippi, University, MS, USA
- Correspondence: Zia Shariat-Madar, University of Mississippi, 219 B, Faser Hall, University, MS 38677–1848, USA, Tel +662 915 5150, Fax +662 915 5148, Email
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Ghrelin in the CNS: from hunger to a rewarding and memorable meal? ACTA ACUST UNITED AC 2008; 58:160-70. [PMID: 18308399 DOI: 10.1016/j.brainresrev.2008.01.004] [Citation(s) in RCA: 47] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2007] [Revised: 01/20/2008] [Accepted: 01/23/2008] [Indexed: 01/19/2023]
Abstract
Ghrelin, the endogenous agonist of the growth hormone secretagogue receptor, has been shown to induce robust feeding responses in numerous experimental models. Although ghrelin comes from both peripheral and central sources, its hyperphagic properties, to a large extent, arise from activity at the brain level. The current review focuses on describing central mechanisms through which this peptide affects consumption. We address the issue of whether ghrelin serves just as a signal of energy needs of the organism or - as suggested by the most recent findings - also affects food intake via other feeding-related mechanisms, including reward and memory. Complexity of ghrelin's role in the regulation of ingestive behavior is discussed by characterizing its influence on consumption, reward and memory as well as by defining its function within the brain circuitry and interplay with other neuropeptides.
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Wu R, Zhou M, Das P, Dong W, Ji Y, Yang D, Miksa M, Zhang F, Ravikumar TS, Wang P. Ghrelin inhibits sympathetic nervous activity in sepsis. Am J Physiol Endocrinol Metab 2007; 293:E1697-702. [PMID: 17911350 DOI: 10.1152/ajpendo.00098.2007] [Citation(s) in RCA: 58] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Our previous studies have shown that norepinephrine (NE) upregulates proinflammatory cytokines by activating alpha(2)-adrenoceptor. Therefore, modulation of the sympathetic nervous system represents a novel treatment for sepsis. We have also shown that a novel stomach-derived peptide, ghrelin, is downregulated in sepsis and that its intravenous administration decreases proinflammatory cytokines and mitigates organ injury. However, it remains unknown whether ghrelin inhibits sympathetic activity through central ghrelin receptors [i.e., growth hormone secretagogue receptor 1a (GHSR-la)] in sepsis. To study this, sepsis was induced in male rats by cecal ligation and puncture (CLP). Ghrelin was administered through intravenous or intracerebroventricular injection 30 min before CLP. Our results showed that intravenous administration of ghrelin significantly reduced the elevated NE and TNF-alpha levels at 2 h after CLP. NE administration partially blocked the inhibitory effect of ghrelin on TNF-alpha in sepsis. GHSR-la inhibition by the administration of a GHSR-la antagonist, [d-Arg(1),d-Phe(5), d-Trp(7,9),Leu(11)]substance P, significantly increased both NE and TNF-alpha levels even in normal animals. Markedly elevated circulating levels of NE 2 h after CLP were also significantly decreased by intracerebroventricular administration of ghrelin. Ghrelin's inhibitory effect on NE release was completely blocked by intracerebroventricular injection of the GHSR-1a antagonist or a neuropeptide Y (NPY)/Y(1) receptor antagonist. However, ghrelin's downregulatory effect on TNF-alpha release was only partially diminished by these agents. Thus ghrelin has sympathoinhibitory properties that are mediated by central ghrelin receptors involving a NPY/Y1 receptor-dependent pathway. Ghrelin's inhibitory effect on TNF-alpha production in sepsis is partially because of its modulation of the overstimulated sympathetic nerve activation.
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Affiliation(s)
- Rongqian Wu
- The Feinstein Institute for Medical Research, 350 Community Dr., Manhasset, NY 11030, USA
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