1
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Fritz EM, Pierre A, De Bundel D, Singewald N. Ghrelin receptor agonist MK0677 and overnight fasting do not rescue deficient fear extinction in 129S1/SvImJ mice. Front Psychiatry 2023; 14:1094948. [PMID: 36846243 PMCID: PMC9947350 DOI: 10.3389/fpsyt.2023.1094948] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/10/2022] [Accepted: 01/03/2023] [Indexed: 02/11/2023] Open
Abstract
The hunger hormone ghrelin has been implicated in the modulation of anxiety- and fear-related behaviors in rodents and humans, while its dysregulation may be associated with psychiatric illness. Along these lines, the ghrelin system has been suggested as a potential target to facilitate fear extinction, which is the main mechanism underlying cognitive behavioral therapy. So far, this hypothesis has not been tested in individuals that have difficulties to extinguish fear. Thus, we investigated pharmacological (ghrelin receptor agonist MK0677) and non-pharmacological (overnight fasting) strategies to target the ghrelin system in the 129S1/SvImJ (S1) mouse strain, which models the endophenotype of impaired fear extinction that has been associated with treatment resistance in anxiety and PTSD patients. MK0677 induced food intake and overnight fasting increased plasma ghrelin levels in S1 mice, suggesting that the ghrelin system is responsive in the S1 strain. However, neither systemic administration of MK0677 nor overnight fasting had an effect on fear extinction in S1 mice. Similarly, our groups previously reported that both interventions did not attenuate fear in extinction-competent C57BL/6J mice. In summary, our findings are in contrast to several studies reporting beneficial effects of GHSR agonism and overnight fasting on fear- and anxiety-related behaviors in rodents. Rather, our data agree with accumulating evidence of divergent behavioral effects of ghrelin system activation and underscore the hypothesis that potential benefits of targeting the ghrelin system in fear extinction may be dependent on factors (e.g., previous stress exposure) that are not yet fully understood.
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Affiliation(s)
- Eva Maria Fritz
- Department of Pharmacology and Toxicology, Institute of Pharmacy and CMBI, University of Innsbruck, Innsbruck, Austria
| | - Anouk Pierre
- Department of Pharmaceutical Sciences, Research Group Experimental Pharmacology, Center for Neurosciences (C4N), Vrije Universiteit Brussel, Brussels, Belgium
| | - Dimitri De Bundel
- Department of Pharmaceutical Sciences, Research Group Experimental Pharmacology, Center for Neurosciences (C4N), Vrije Universiteit Brussel, Brussels, Belgium
| | - Nicolas Singewald
- Department of Pharmacology and Toxicology, Institute of Pharmacy and CMBI, University of Innsbruck, Innsbruck, Austria
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2
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Peris-Sampedro F, Le May MV, Stoltenborg I, Schéle E, Dickson SL. A skeleton in the cupboard in ghrelin research: Where are the skinny dwarfs? J Neuroendocrinol 2021; 33:e13025. [PMID: 34427011 DOI: 10.1111/jne.13025] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/30/2021] [Revised: 07/09/2021] [Accepted: 08/05/2021] [Indexed: 12/15/2022]
Abstract
Based on studies delivering ghrelin or ghrelin receptor agonists, we have learned a great deal about the importance of the brain ghrelin signalling system for a wide range of physiological processes that include feeding behaviours, growth hormone secretion and glucose homeostasis. Because these processes can be considered as essential to life, the question arises as to why mouse models of depleted ghrelin signalling are not all skinny dwarfs with a host of behavioural and metabolic problems. Here, we provide a systematic detailed review of the phenotype of mice with deficient ghrelin signalling to help better understand the relevance and importance of the brain ghrelin signalling system, with a particular emphasis on those questions that remain unanswered.
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Affiliation(s)
- Fiona Peris-Sampedro
- Department of Physiology/Endocrine, Institute of Neuroscience and Physiology, The Sahlgrenska Academy at the University of Gothenburg, Gothenburg, Sweden
| | - Marie V Le May
- Department of Physiology/Endocrine, Institute of Neuroscience and Physiology, The Sahlgrenska Academy at the University of Gothenburg, Gothenburg, Sweden
| | - Iris Stoltenborg
- Department of Physiology/Endocrine, Institute of Neuroscience and Physiology, The Sahlgrenska Academy at the University of Gothenburg, Gothenburg, Sweden
| | - Erik Schéle
- Department of Physiology/Endocrine, Institute of Neuroscience and Physiology, The Sahlgrenska Academy at the University of Gothenburg, Gothenburg, Sweden
| | - Suzanne L Dickson
- Department of Physiology/Endocrine, Institute of Neuroscience and Physiology, The Sahlgrenska Academy at the University of Gothenburg, Gothenburg, Sweden
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3
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Chronic Inhibition of FAAH Reduces Depressive-Like Behavior and Improves Dentate Gyrus Proliferation after Chronic Unpredictable Stress Exposure. Behav Neurol 2021; 2021:6651492. [PMID: 33833828 PMCID: PMC8016565 DOI: 10.1155/2021/6651492] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2020] [Revised: 02/24/2021] [Accepted: 03/18/2021] [Indexed: 02/08/2023] Open
Abstract
Symptoms of depressive disorders such as anhedonia and despair can be a product of an aberrant adaptation to stress conditions. Chronic unpredictable stress model (CUS) can generate an increase in the activity of the hypothalamic-pituitary-adrenal axis (HPA) and induce a reduction of neurotrophin signaling and the proliferation of neural progenitors in the adult dentate gyrus, together with increased oxidative stress. Levels of the endocannabinoid anandamide (AEA) seem to affect these depression-by-stress-related features and could be modulated by fatty acid amide hydrolase (FAAH). We aimed to evaluate the effects of FAAH inhibitor, URB597, on depressive-like behavior and neural proliferation of mice subjected to a model of CUS. URB597 was administered intraperitoneally at a dose of 0.2 mg/kg for 14 days after CUS. Depressive-like behaviors, anhedonia, and despair were evaluated in the splash and forced swimming tests, respectively. Alterations at the HPA axis level were analyzed using the relative weight of adrenal glands and serum corticosterone levels. Oxidative stress and brain-derived neurotrophic factor (BDNF) were also evaluated. Fluorescence immunohistochemistry tests were performed for the immunoreactivity of BrdU and Sox2 colabeling for comparison of neural precursors. The administration of URB597 was able to reverse the depressive-like behavior generated in mice after the model. Likewise, other physiological responses associated with CUS were reduced in the treated group, among them, increase in the relative weight of the adrenal glands, increased oxidative stress, and decreased BDNF and number of neural precursors. Most of these auspicious responses to enzyme inhibitor administration were blocked by employing a cannabinoid receptor antagonist. In conclusion, the chronic inhibition of FAAH generated an antidepressant effect, promoting neural progenitor proliferation and BDNF expression, while reducing adrenal gland weight and oxidative stress in mice under the CUS model.
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4
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Berry A, Mazzelli M, Musillo C, Riva MA, Cattaneo A, Cirulli F. High-fat diet during adulthood interacts with prenatal stress, affecting both brain inflammatory and neuroendocrine markers in male rats. Eur J Neurosci 2021; 55:2326-2340. [PMID: 33711185 DOI: 10.1111/ejn.15181] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2020] [Revised: 03/04/2021] [Accepted: 03/04/2021] [Indexed: 02/06/2023]
Abstract
Prenatal stress (PNS) affects foetal programming and, through an interaction with subsequent challenges, can increase vulnerability to mood and metabolic disorders. We have previously shown that, following PNS, adult male rats are characterized by increased vulnerability to a metabolic stressor experienced at adulthood (8-week-high-fat diet-HFD). In this study, we specifically assessed whether PNS might interact with an adult metabolic challenge to induce an inflammatory phenotype. Changes in the expression levels of inflammatory (Il-1β, Tnf-α, Il-6) and of stress response mediators (Nr3c1, Fkbp5) as well as of mood and metabolic regulators (Bdnf, Ghs-R) were investigated in the hippocampus, prefrontal cortex and hypothalamus, brain regions involved in the pathogenesis of depression and prone to inflammation in response to stress. Overall, PNS reduced the expression of Bdnf and Tnf-α, while HFD administered at adulthood counteracted this effect suggesting that PNS impinges upon the same pathways regulating responses to a metabolic challenge at adulthood. Furthermore, HFD and PNS affected the expression of both Nr3c1 and Fkbp5, two neuroendocrine mediators involved in the response to stress, metabolic challenges and in the modulation of the emotional profile (as shown by the correlation between Fkbp5 and the time spent in the open arms of the elevated plus-maze). Overall, these results indicate that the same metabolic and neuroendocrine effectors engaged by PNS are affected by metabolic challenges at adulthood, providing some mechanistic insight into the well-known comorbidity between mood and metabolic disorders.
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Affiliation(s)
- Alessandra Berry
- Center for Behavioral Sciences and Mental Health, Istituto Superiore di Sanità, Rome, Italy
| | - Monica Mazzelli
- Biological Psychiatry Laboratory, IRCCS Istituto Centro San Giovanni di Dio Fatebenefratelli, Brescia, Italy.,Department of Pharmacological and Biomolecular Sciences, University of Milan, Milan, Italy
| | - Chiara Musillo
- Center for Behavioral Sciences and Mental Health, Istituto Superiore di Sanità, Rome, Italy.,PhD Program in Behavioral Neuroscience, Department of Psychology, Sapienza University of Rome, Rome, Italy
| | - Marco Andrea Riva
- Biological Psychiatry Laboratory, IRCCS Istituto Centro San Giovanni di Dio Fatebenefratelli, Brescia, Italy.,Department of Pharmacological and Biomolecular Sciences, University of Milan, Milan, Italy
| | - Annamaria Cattaneo
- Biological Psychiatry Laboratory, IRCCS Istituto Centro San Giovanni di Dio Fatebenefratelli, Brescia, Italy.,Department of Pharmacological and Biomolecular Sciences, University of Milan, Milan, Italy
| | - Francesca Cirulli
- Center for Behavioral Sciences and Mental Health, Istituto Superiore di Sanità, Rome, Italy
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5
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Fritz EM, Singewald N, De Bundel D. The Good, the Bad and the Unknown Aspects of Ghrelin in Stress Coping and Stress-Related Psychiatric Disorders. Front Synaptic Neurosci 2020; 12:594484. [PMID: 33192444 PMCID: PMC7652849 DOI: 10.3389/fnsyn.2020.594484] [Citation(s) in RCA: 22] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/13/2020] [Accepted: 09/14/2020] [Indexed: 12/16/2022] Open
Abstract
Ghrelin is a peptide hormone released by specialized X/A cells in the stomach and activated by acylation. Following its secretion, it binds to ghrelin receptors in the periphery to regulate energy balance, but it also acts on the central nervous system where it induces a potent orexigenic effect. Several types of stressors have been shown to stimulate ghrelin release in rodents, including nutritional stressors like food deprivation, but also physical and psychological stressors such as foot shocks, social defeat, forced immobilization or chronic unpredictable mild stress. The mechanism through which these stressors drive ghrelin release from the stomach lining remains unknown and, to date, the resulting consequences of ghrelin release for stress coping remain poorly understood. Indeed, ghrelin has been proposed to act as a stress hormone that reduces fear, anxiety- and depression-like behaviors in rodents but some studies suggest that ghrelin may - in contrast - promote such behaviors. In this review, we aim to provide a comprehensive overview of the literature on the role of the ghrelin system in stress coping. We discuss whether ghrelin release is more than a byproduct of disrupted energy homeostasis following stress exposure. Furthermore, we explore the notion that ghrelin receptor signaling in the brain may have effects independent of circulating ghrelin and in what way this might influence stress coping in rodents. Finally, we examine how the ghrelin system could be utilized as a therapeutic avenue in stress-related psychiatric disorders (with a focus on anxiety- and trauma-related disorders), for example to develop novel biomarkers for a better diagnosis or new interventions to tackle relapse or treatment resistance in patients.
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Affiliation(s)
- Eva Maria Fritz
- Department of Pharmacology and Toxicology, Institute of Pharmacy and CMBI, University of Innsbruck, Innsbruck, Austria
| | - Nicolas Singewald
- Department of Pharmacology and Toxicology, Institute of Pharmacy and CMBI, University of Innsbruck, Innsbruck, Austria
| | - Dimitri De Bundel
- Department of Pharmaceutical Sciences, Research Group Experimental Pharmacology, Center for Neurosciences (C4N), Vrije Universiteit Brussel, Brussels, Belgium
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6
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Hay RE, Edwards A, Klein M, Hyland L, MacDonald D, Karatsoreos I, Hill MN, Abizaid A. Ghrelin Receptor Signaling Is Not Required for Glucocorticoid-Induced Obesity in Male Mice. Endocrinology 2020; 161:5636885. [PMID: 31748785 PMCID: PMC7445420 DOI: 10.1210/endocr/bqz023] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/12/2019] [Accepted: 11/19/2019] [Indexed: 12/11/2022]
Abstract
Chronically elevated levels of glucocorticoids increase food intake, weight gain, and adiposity. Similarly, ghrelin, a gut-secreted hormone, is also associated with weight gain, adiposity, and increased feeding. Here we sought to determine if corticosterone-induced metabolic and behavioral changes require functional ghrelin receptors (GHSR). To do this, we treated male C57BL mice with chronic corticosterone (CORT) mixed in their drinking water for 28 days. Half of these mice received the GHSR antagonist JMV2959 via osmotic minipumps while treated with CORT. In a second experiment, we gave the same CORT protocol to mice with a targeted mutation to the GHSR or their wild-type littermates. As expected, CORT treatment increased food intake, weight gain, and adiposity, but contrary to expectations, mice treated with a GHSR receptor antagonist or GHSR knockout (KO) mice did not show attenuated food intake, weight gain, or adiposity in response to CORT. Similarly, the effects of CORT on the liver were the same or more pronounced in GHSR antagonist-treated and GHSR KO mice. Treatment with JMV2959 did attenuate the effects of chronic CORT on glycemic regulation as determined by the glucose tolerance test. Finally, disruption of GHSR signaling resulted in behavioral responses associated with social withdrawal, potentially due to neuroprotective effects of GHSR activation. In all, we propose that blocking GHSR signaling helps to moderate glucose concentrations when CORT levels are high, but blocking GHSR signaling does not prevent increased food intake, weight gain, or increased adiposity produced by chronic CORT.
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Affiliation(s)
- Rebecca E Hay
- Department of Neuroscience, Carleton University, Ottawa, ON, Canada
| | - Alex Edwards
- Department of Neuroscience, Carleton University, Ottawa, ON, Canada
| | - Marianne Klein
- Department of Neuroscience, Carleton University, Ottawa, ON, Canada
| | - Lindsay Hyland
- Department of Neuroscience, Carleton University, Ottawa, ON, Canada
| | - David MacDonald
- Department of Neuroscience, Carleton University, Ottawa, ON, Canada
| | - Ilia Karatsoreos
- Department of Integrative Physiology and Neuroscience, Washington State University, Pullman, WA, US
| | - Matthew N Hill
- Hotchkiss Brain Institute, Department of Cell Biology and Anatomy, University of Calgary, Calgary, AB, Canada
| | - Alfonso Abizaid
- Department of Neuroscience, Carleton University, Ottawa, ON, Canada
- Correspondence: Alfonso Abizaid, Department of Neuroscience, Carleton University, 1125 Colonel By Drive, Ottawa, ON K1S5B6, Canada. E-mail:
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7
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Kudryashov NV, Kalinina TS, Shimshirt AA, Volkova AV, Narkevich VB, Naplekova PL, Kasabov KA, Kudrin VS, Voronina TA, Fisenko VP. The Behavioral and Neurochemical Aspects of the Interaction between Antidepressants and Unpredictable Chronic Mild Stress. Acta Naturae 2020; 12:63-72. [PMID: 32477600 PMCID: PMC7245955 DOI: 10.32607/actanaturae.10942] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2019] [Accepted: 01/29/2020] [Indexed: 01/28/2023] Open
Abstract
The behavioral and neurochemical effects of amitriptyline (10 mg/kg, i.p.) and fluoxetine (20 mg/kg, i.p.) after single and chronic administration in the setting of unpredictable mild stress in outbred ICR (CD-1) mice were studied. After a 28-day exposure to stress, we observed an increase in depressive reaction in a forced swim test in mice, as well as reduced hippocampal levels of serotonin (5-hydroxytryptamine, 5-HT) and 5-hydroxyindoleacetic acid (5-HIAA) and an increased hypothalamic level of noradrenaline (NA). Single and chronic administration of amitriptyline and fluoxetine shortened the immobility period and increased the time corresponding to active swimming in the forced swim test. The antidepressant-like effect of fluoxetine - but not of amitriptyline - after a single injection coincided with an increase in the 5-HT turnover in the hippocampus. Chronic administration of the antidepressants increased the hypothalamic levels of NA. Thus, the antidepressant- like effect of amitriptyline and fluoxetine may result from an enhancement of the stress-dependent adaptive mechanisms depleted by chronic stress.
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Affiliation(s)
- N. V. Kudryashov
- Federal State Budgetary Institution «Research Zakusov Institute of Pharmacology», Moscow, 125315 Russia
- Sechenov First Moscow State Medical University (Sechenov University), Moscow, 119991 Russia
- N.K. Koltsov Institute of Developmental Biology RAS, Moscow, 119334 Russia
| | - T. S. Kalinina
- Federal State Budgetary Institution «Research Zakusov Institute of Pharmacology», Moscow, 125315 Russia
- N.K. Koltsov Institute of Developmental Biology RAS, Moscow, 119334 Russia
| | - A. A. Shimshirt
- Federal State Budgetary Institution «Research Zakusov Institute of Pharmacology», Moscow, 125315 Russia
| | - A. V. Volkova
- Federal State Budgetary Institution «Research Zakusov Institute of Pharmacology», Moscow, 125315 Russia
| | - V. B. Narkevich
- Federal State Budgetary Institution «Research Zakusov Institute of Pharmacology», Moscow, 125315 Russia
| | - P. L. Naplekova
- Federal State Budgetary Institution «Research Zakusov Institute of Pharmacology», Moscow, 125315 Russia
| | - K. A. Kasabov
- Federal State Budgetary Institution «Research Zakusov Institute of Pharmacology», Moscow, 125315 Russia
| | - V. S. Kudrin
- Federal State Budgetary Institution «Research Zakusov Institute of Pharmacology», Moscow, 125315 Russia
| | - T. A. Voronina
- Federal State Budgetary Institution «Research Zakusov Institute of Pharmacology», Moscow, 125315 Russia
| | - V. P. Fisenko
- Sechenov First Moscow State Medical University (Sechenov University), Moscow, 119991 Russia
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8
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Turkson S, Kloster A, Hamilton PJ, Neigh GN. Neuroendocrine drivers of risk and resilience: The influence of metabolism & mitochondria. Front Neuroendocrinol 2019; 54:100770. [PMID: 31288042 PMCID: PMC6886586 DOI: 10.1016/j.yfrne.2019.100770] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/02/2019] [Revised: 06/20/2019] [Accepted: 07/03/2019] [Indexed: 02/07/2023]
Abstract
The manifestation of risk versus resilience has been considered from varying perspectives including genetics, epigenetics, early life experiences, and type and intensity of the challenge with which the organism is faced. Although all of these factors are central to determining risk and resilience, the current review focuses on what may be a final common pathway: metabolism. When an organism is faced with a perturbation to the environment, whether internal or external, appropriate energy allocation is essential to resolving the divergence from equilibrium. This review examines the potential role of metabolism in the manifestation of stress-induced neural compromise. In addition, this review details the current state of knowledge on neuroendocrine factors which are poised to set the tone of the metabolic response to a systemic challenge. The goal is to provide an essential framework for understanding stress in a metabolic context and appreciation for key neuroendocrine signals.
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Affiliation(s)
- Susie Turkson
- Department of Anatomy & Neurobiology, Virginia Commonwealth University, Richmond, VA, United States
| | - Alix Kloster
- Department of Anatomy & Neurobiology, Virginia Commonwealth University, Richmond, VA, United States
| | - Peter J Hamilton
- Department of Anatomy & Neurobiology, Virginia Commonwealth University, Richmond, VA, United States
| | - Gretchen N Neigh
- Department of Anatomy & Neurobiology, Virginia Commonwealth University, Richmond, VA, United States.
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9
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Abizaid A. Stress and obesity: The ghrelin connection. J Neuroendocrinol 2019; 31:e12693. [PMID: 30714236 DOI: 10.1111/jne.12693] [Citation(s) in RCA: 29] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/15/2018] [Revised: 01/01/2019] [Accepted: 01/29/2019] [Indexed: 12/20/2022]
Abstract
Ghrelin is a hormone associated with feeding and energy balance. Not surprisingly, this hormone is secreted in response to acute stressors and it is chronically elevated after exposure to chronic stress in tandem with a number of metabolic changes aimed at attaining homeostatic balance. In the present review, we propose that ghrelin plays a key role in these stress-induced homeostatic processes. Ghrelin targets the hypothalamus and brain stem nuclei that are part of the sympathetic nervous system to increase appetite and energy expenditure and promote the use of carbohydrates as a source of fuel at the same time as sparing fat. Ghrelin also targets mesolimbic brain regions such as the ventral segmental area and the hippocampus to modulate reward processes, to protect against damage associated with chronic stress, as well as to potentially increase resilience to stress. In all, these data support the notion that ghrelin, similar to corticosterone, is a critical metabolic hormone that is essential for the stress response.
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Affiliation(s)
- Alfonso Abizaid
- Department of Neuroscience, Carleton University, Ottawa, Ontario, Canada
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10
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Di Natale MR, Soch A, Ziko I, De Luca SN, Spencer SJ, Sominsky L. Chronic predator stress in female mice reduces primordial follicle numbers: implications for the role of ghrelin. J Endocrinol 2019; 241:201-219. [PMID: 30959480 DOI: 10.1530/joe-19-0109] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/27/2019] [Accepted: 04/04/2019] [Indexed: 12/17/2022]
Abstract
Chronic stress is a known suppressor of female reproductive function. However, attempts to isolate single causal links between stress and reproductive dysfunction have not yet been successful due to their multi-faceted aetiologies. The gut-derived hormone ghrelin regulates stress and reproductive function and may therefore be pivotal in the neuroendocrine integration of the hypothalamic-pituitary-adrenal (HPA) and -gonadal (HPG) axes. Here, we hypothesised that chronic stress disrupts ovarian follicle maturation and that this effect is mediated by a stress-induced increase in acyl ghrelin and activation of the growth hormone secretatogue receptor (GHSR). We gave C57BL/6J female mice 30 min daily chronic predator stress for 4 weeks, or no stress, and gave them daily GHSR antagonist (d-Lys3-GHRP-6) or saline. Exposure to chronic predator stress reduced circulating corticosterone, elevated acyl ghrelin levels and led to significantly depleted primordial follicle numbers. GHSR antagonism stress-dependently altered the expression of genes regulating ovarian responsiveness to gonadotropins and was able to attenuate the stress-induced depletion of primordial follicles. These findings suggest that chronic stress-induced elevations of acyl ghrelin may be detrimental for ovarian follicle maturation.
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Affiliation(s)
- Madeleine R Di Natale
- School of Health and Biomedical Sciences, RMIT University, Melbourne, Victoria, Australia
| | - Alita Soch
- School of Health and Biomedical Sciences, RMIT University, Melbourne, Victoria, Australia
| | - Ilvana Ziko
- School of Health and Biomedical Sciences, RMIT University, Melbourne, Victoria, Australia
| | - Simone N De Luca
- School of Health and Biomedical Sciences, RMIT University, Melbourne, Victoria, Australia
| | - Sarah J Spencer
- School of Health and Biomedical Sciences, RMIT University, Melbourne, Victoria, Australia
| | - Luba Sominsky
- School of Health and Biomedical Sciences, RMIT University, Melbourne, Victoria, Australia
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11
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Balsevich G, Abizaid A, Chen A, Karatsoreos IN, Schmidt MV. Stress and glucocorticoid modulation of feeding and metabolism. Neurobiol Stress 2019; 11:100171. [PMID: 31193462 PMCID: PMC6529856 DOI: 10.1016/j.ynstr.2019.100171] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2018] [Revised: 05/07/2019] [Accepted: 05/14/2019] [Indexed: 12/04/2022] Open
Abstract
This perspective highlights research presented as part of the symposium entitled, “Stress and Glucocorticoid Modulation of Feeding and Metabolism” at the 2018 Neurobiology of Stress Workshop held in Banff, AB, Canada. The symposium comprised five researchers at different career stages who each study different aspects of the interaction between the stress response and metabolic control. Their collective results reveal the complexity of this relationship in terms of behavioural and physiological outcomes. Their work emphasizes the need to consider the level of interaction (cellular, tissue, systems) as well as the timing and context in which the interaction is studied. Rather than a comprehensive review on the work presented at the Symposium, here we discuss recurring themes that emerged at the biennial workshop, which address new avenues of research that will drive the field forward.
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Affiliation(s)
- G Balsevich
- Hotchkiss Brain Institute, University of Calgary, 3330 Hospital Dr NW, Calgary, AB, T2N 4N1, Canada
| | - A Abizaid
- Institute of Neuroscience, Carleton University, 1125 Colonel By Drive, Ottawa, ON, K1S 5B6, Canada
| | - A Chen
- Department of Stress Neurobiology and Neurogenetics, Max Planck Institute of Psychiatry, Kraepelinstrasse 2 - 10, Munich, 80804, Germany
| | - I N Karatsoreos
- Department of Integrative Physiology and Neuroscience, Washington State University, 1815 Ferdinand's Lane, Pullman, WA, 99164, United States
| | - M V Schmidt
- Department of Stress Neurobiology and Neurogenetics, Max Planck Institute of Psychiatry, Kraepelinstrasse 2 - 10, Munich, 80804, Germany
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12
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Abbas A, Yu L, Lalonde T, Wu D, Thiessen JD, Luyt LG, Dhanvantari S. Development and Characterization of an 18F-labeled Ghrelin Peptidomimetic for Imaging the Cardiac Growth Hormone Secretagogue Receptor. Mol Imaging 2018; 17:1536012118809587. [PMID: 30394854 PMCID: PMC6236854 DOI: 10.1177/1536012118809587] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023] Open
Abstract
One-third of patients with heart disease develop heart failure, which is diagnosed
through imaging and detection of circulating biomarkers. Imaging strategies reveal
morphologic and functional changes but fall short of detecting molecular abnormalities
that can lead to heart failure, and circulating biomarkers are not cardiac specific. Thus,
there is critical need for biomarkers that are endogenous to myocardial tissues. The
cardiac growth hormone secretagogue receptor 1a (GHSR1a), which binds the hormone ghrelin,
is a potential biomarker for heart failure. We have synthesized and characterized a novel
ghrelin peptidomimetic tracer, an 18F-labeled analogue of G-7039, for positron
emission tomography (PET) imaging of cardiac GHSR1a. In vitro analysis showed enhanced
serum stability compared to natural ghrelin and significantly increased cellular uptake in
GHSR1a-expressing OVCAR cells. Biodistribution studies in mice showed that tissue uptake
of the tracer was independent of circulating ghrelin levels, and there was negligible
cardiac uptake and high uptake in the liver, intestines, and kidneys. Specificity of
tracer uptake was assessed using ghsr −/− mice; both static and dynamic PET imaging revealed no difference in cardiac
uptake, and there was no significant correlation between cardiac standardized uptake
values and GHSR1a expression. Our study lays the groundwork for further refinement of
peptidomimetic PET tracers targeting cardiac GHSR1a.
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Affiliation(s)
- Ahmed Abbas
- 1 Department of Medical Biophysics, Western University, London, Ontario, Canada
| | - Lihai Yu
- 2 Department of Chemistry, Western University, London, Ontario, Canada
| | - Tyler Lalonde
- 2 Department of Chemistry, Western University, London, Ontario, Canada
| | - Derek Wu
- 3 Department of Pathology and Laboratory Medicine, Western University, London, Ontario, Canada
| | - Jonathan D Thiessen
- 1 Department of Medical Biophysics, Western University, London, Ontario, Canada.,4 Imaging Research, Lawson Health Research Institute, London, Ontario, Canada
| | - Leonard G Luyt
- 2 Department of Chemistry, Western University, London, Ontario, Canada.,4 Imaging Research, Lawson Health Research Institute, London, Ontario, Canada.,5 Department of oncology, Western University, London, Ontario, Canada
| | - Savita Dhanvantari
- 1 Department of Medical Biophysics, Western University, London, Ontario, Canada.,3 Department of Pathology and Laboratory Medicine, Western University, London, Ontario, Canada.,4 Imaging Research, Lawson Health Research Institute, London, Ontario, Canada.,6 Metabolism/Diabetes, Lawson Health Research Institute, London, Ontario, Canada
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13
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Naish KR, Laliberte M, MacKillop J, Balodis IM. Systematic review of the effects of acute stress in binge eating disorder. Eur J Neurosci 2018; 50:2415-2429. [DOI: 10.1111/ejn.14110] [Citation(s) in RCA: 26] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2018] [Revised: 07/03/2018] [Accepted: 08/07/2018] [Indexed: 12/01/2022]
Affiliation(s)
- Katherine R. Naish
- Peter Boris Centre for Addictions Research Department of Psychiatry and Behavioural Neurosciences McMaster University and St. Joseph's Healthcare Hamilton Hamilton ON Canada
| | - Michele Laliberte
- Peter Boris Centre for Addictions Research Department of Psychiatry and Behavioural Neurosciences McMaster University and St. Joseph's Healthcare Hamilton Hamilton ON Canada
- Eating Disorders Clinic St. Joseph's Healthcare Hamilton Hamilton ON Canada
- Michael G. DeGroote Centre for Medicinal Cannabis Research Michael G. DeGroote School of Medicine McMaster University and St. Joseph's Healthcare Hamilton Hamilton ON Canada
| | - James MacKillop
- Peter Boris Centre for Addictions Research Department of Psychiatry and Behavioural Neurosciences McMaster University and St. Joseph's Healthcare Hamilton Hamilton ON Canada
- Michael G. DeGroote Centre for Medicinal Cannabis Research Michael G. DeGroote School of Medicine McMaster University and St. Joseph's Healthcare Hamilton Hamilton ON Canada
| | - Iris M. Balodis
- Peter Boris Centre for Addictions Research Department of Psychiatry and Behavioural Neurosciences McMaster University and St. Joseph's Healthcare Hamilton Hamilton ON Canada
- Michael G. DeGroote Centre for Medicinal Cannabis Research Michael G. DeGroote School of Medicine McMaster University and St. Joseph's Healthcare Hamilton Hamilton ON Canada
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14
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Wang C, Gan D, Wu J, Liao M, Liao X, Ai W. Honokiol Exerts Antidepressant Effects in Rats Exposed to Chronic Unpredictable Mild Stress by Regulating Brain Derived Neurotrophic Factor Level and Hypothalamus-Pituitary-Adrenal Axis Activity. Neurochem Res 2018; 43:1519-1528. [PMID: 29855846 DOI: 10.1007/s11064-018-2566-z] [Citation(s) in RCA: 20] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2018] [Revised: 05/22/2018] [Accepted: 05/28/2018] [Indexed: 12/17/2022]
Abstract
Honokiol (HNK), the main active component of Magnolia officinalis, has shown a variety of pharmacological activities. In the present study, we measured the antidepressant-like effects of HNK in a rat model of chronic unpredictable mild stress (CUMS) and explored its possible mechanisms. The antidepressant-like effects of HNK were assessed in rats by an open field test (OFT), sucrose preference test (SPT) and forced swimming test (FST). Then, serum levels of corticotrophin-releasing hormone (CRH), adrenocorticotropic hormone (ACTH) and corticosterone (CORT) and hippocampal brain-derived neurotrophic factor (BDNF) and glucocorticoid receptor α (GRα) levels were assessed to explore the possible mechanisms. We identified that HNK treatment (2, 4, and 8 mg/kg) alleviated the CUMS-induced behavioural deficits. Treatment with HNK also normalized the CUMS-induced hyperactivity of the limbic hypothalamic-pituitary-adrenal (HPA) axis, as indicated by reduced CRH, ACTH and CORT serum levels. In addition, HNK increased the expression of GRα (mRNA and protein) and BDNF (mRNA and protein) in the hippocampus. These data confirmed the antidepressant-like effects of HNK, which may be related to its normalizing the function of the HPA axis and increasing the BDNF level in the hippocampus.
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Affiliation(s)
- Canmao Wang
- Department of Pharmacy, Shenzhen University General Hospital, Shenzhen, Guangdong, 518000, China
| | - Danna Gan
- Department of Pharmacy, Shenzhen Hospital, Southern Medical University, Shenzhen, Guangdong, 518000, China
| | - Jingang Wu
- The Second People's Hospital of China Three Gorges University, Yichang, Hubei, 443000, China
| | - Minhui Liao
- Department of Pharmacy, Shenzhen Hospital, Southern Medical University, Shenzhen, Guangdong, 518000, China
| | - Xinghuan Liao
- Department of Pharmacy, Shenzhen University General Hospital, Shenzhen, Guangdong, 518000, China
| | - Weipeng Ai
- Department of Pharmacy, Shenzhen University General Hospital, Shenzhen, Guangdong, 518000, China.
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15
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Lach G, Schellekens H, Dinan TG, Cryan JF. Anxiety, Depression, and the Microbiome: A Role for Gut Peptides. Neurotherapeutics 2018; 15:36-59. [PMID: 29134359 PMCID: PMC5794698 DOI: 10.1007/s13311-017-0585-0] [Citation(s) in RCA: 307] [Impact Index Per Article: 51.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
The complex bidirectional communication between the gut and the brain is finely orchestrated by different systems, including the endocrine, immune, autonomic, and enteric nervous systems. Moreover, increasing evidence supports the role of the microbiome and microbiota-derived molecules in regulating such interactions; however, the mechanisms underpinning such effects are only beginning to be resolved. Microbiota-gut peptide interactions are poised to be of great significance in the regulation of gut-brain signaling. Given the emerging role of the gut-brain axis in a variety of brain disorders, such as anxiety and depression, it is important to understand the contribution of bidirectional interactions between peptide hormones released from the gut and intestinal bacteria in the context of this axis. Indeed, the gastrointestinal tract is the largest endocrine organ in mammals, secreting dozens of different signaling molecules, including peptides. Gut peptides in the systemic circulation can bind cognate receptors on immune cells and vagus nerve terminals thereby enabling indirect gut-brain communication. Gut peptide concentrations are not only modulated by enteric microbiota signals, but also vary according to the composition of the intestinal microbiota. In this review, we will discuss the gut microbiota as a regulator of anxiety and depression, and explore the role of gut-derived peptides as signaling molecules in microbiome-gut-brain communication. Here, we summarize the potential interactions of the microbiota with gut hormones and endocrine peptides, including neuropeptide Y, peptide YY, pancreatic polypeptide, cholecystokinin, glucagon-like peptide, corticotropin-releasing factor, oxytocin, and ghrelin in microbiome-to-brain signaling. Together, gut peptides are important regulators of microbiota-gut-brain signaling in health and stress-related psychiatric illnesses.
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Affiliation(s)
- Gilliard Lach
- APC Microbiome Institute, University College Cork, Cork, Ireland
| | - Harriet Schellekens
- APC Microbiome Institute, University College Cork, Cork, Ireland
- Department of Anatomy and Neuroscience, University College Cork, Cork, Ireland
- Food for Health Ireland, University College Cork, Cork, Ireland
| | - Timothy G Dinan
- APC Microbiome Institute, University College Cork, Cork, Ireland
- Department of Psychiatry and Neurobehavioural Science, University College Cork, Cork, Ireland
| | - John F Cryan
- APC Microbiome Institute, University College Cork, Cork, Ireland.
- Food for Health Ireland, University College Cork, Cork, Ireland.
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16
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Sominsky L, Hodgson DM, McLaughlin EA, Smith R, Wall HM, Spencer SJ. Linking Stress and Infertility: A Novel Role for Ghrelin. Endocr Rev 2017; 38:432-467. [PMID: 28938425 DOI: 10.1210/er.2016-1133] [Citation(s) in RCA: 34] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/17/2016] [Accepted: 07/24/2017] [Indexed: 12/23/2022]
Abstract
Infertility affects a remarkable one in four couples in developing countries. Psychological stress is a ubiquitous facet of life, and although stress affects us all at some point, prolonged or unmanageable stress may become harmful for some individuals, negatively impacting on their health, including fertility. For instance, women who struggle to conceive are twice as likely to suffer from emotional distress than fertile women. Assisted reproductive technology treatments place an additional physical, emotional, and financial burden of stress, particularly on women, who are often exposed to invasive techniques associated with treatment. Stress-reduction interventions can reduce negative affect and in some cases to improve in vitro fertilization outcomes. Although it has been well-established that stress negatively affects fertility in animal models, human research remains inconsistent due to individual differences and methodological flaws. Attempts to isolate single causal links between stress and infertility have not yet been successful due to their multifaceted etiologies. In this review, we will discuss the current literature in the field of stress-induced reproductive dysfunction based on animal and human models, and introduce a recently unexplored link between stress and infertility, the gut-derived hormone, ghrelin. We also present evidence from recent seminal studies demonstrating that ghrelin has a principal role in the stress response and reward processing, as well as in regulating reproductive function, and that these roles are tightly interlinked. Collectively, these data support the hypothesis that stress may negatively impact upon fertility at least in part by stimulating a dysregulation in ghrelin signaling.
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Affiliation(s)
- Luba Sominsky
- School of Health and Biomedical Sciences, RMIT University, Melbourne, Victoria 3083, Australia
| | - Deborah M Hodgson
- School of Psychology, Faculty of Science and IT, The University of Newcastle, New South Wales 2308, Australia
| | - Eileen A McLaughlin
- School of Biological Sciences, Faculty of Science, The University of Auckland, Auckland 1010, New Zealand.,School of Environmental & Life Sciences, Faculty of Science and IT, The University of Newcastle, New South Wales 2308, Australia
| | - Roger Smith
- Mothers and Babies Research Centre, Hunter Medical Research Institute, Lookout Road, New Lambton Heights, New South Wales 2305, Australia.,Priority Research Centre in Reproductive Science, The University of Newcastle, New South Wales 2308, Australia
| | - Hannah M Wall
- School of Health and Biomedical Sciences, RMIT University, Melbourne, Victoria 3083, Australia
| | - Sarah J Spencer
- School of Health and Biomedical Sciences, RMIT University, Melbourne, Victoria 3083, Australia
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17
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Azegami T, Yuki Y, Sawada S, Mejima M, Ishige K, Akiyoshi K, Itoh H, Kiyono H. Nanogel-based nasal ghrelin vaccine prevents obesity. Mucosal Immunol 2017; 10:1351-1360. [PMID: 28120848 DOI: 10.1038/mi.2016.137] [Citation(s) in RCA: 31] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2016] [Accepted: 12/19/2016] [Indexed: 02/04/2023]
Abstract
Obesity is associated with multiple comorbidities such as cardiovascular diseases and has a huge economic impact on the health-care system. However, the treatment of obesity remains insufficient in terms of efficacy, tolerability, and safety. Here we created a nasal vaccine against obesity for the first time. To avoid the injectable administration-caused pain and skin-related adverse event, we focused on the intranasal route of antigen delivery. We developed a vaccine antigen (ghrelin-PspA (pneumococcal surface protein A)), which is a recombinant fusion protein incorporating ghrelin, a hormone that stimulates food intake and decreases energy expenditure, and PspA, a candidate of pneumococcal vaccine as a carrier protein. Ghrelin-PspA antigen was mixed with cyclic di-GMP adjuvant to enhance the immunogenicity and incorporated within a nanometer-sized hydrogel for the effective antigen delivery. Intranasal immunization with ghrelin-PspA vaccine elicited serum immunoglobulin G antibodies against ghrelin and attenuated body weight gain in diet-induced obesity mice. This obesity-attenuating effect was caused by a decrease in fat accumulation and an increase in energy expenditure that was partially due to an increase in the expression of mitochondrial uncoupling protein 1 in brown adipose tissue. The development of this nasal vaccine provides a new strategy for the prevention and treatment of obesity.
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Affiliation(s)
- T Azegami
- Department of Internal Medicine, School of Medicine, Keio University, Tokyo, Japan.,Division of Mucosal Immunology, Department of Microbiology and Immunology, The Institute of Medical Science, The University of Tokyo, Tokyo, Japan.,International Research and Development Center for Mucosal Vaccines, The Institute of Medical Science, The University of Tokyo, Tokyo, Japan
| | - Y Yuki
- Division of Mucosal Immunology, Department of Microbiology and Immunology, The Institute of Medical Science, The University of Tokyo, Tokyo, Japan.,International Research and Development Center for Mucosal Vaccines, The Institute of Medical Science, The University of Tokyo, Tokyo, Japan
| | - S Sawada
- Department of Polymer Chemistry, Graduate School of Engineering, Kyoto University, Kyoto, Japan.,Japan Science and Technology Agency (JST), The Exploratory Research for Advanced Technology (ERATO), Katura Int' Tech Center, Kyoto, Japan
| | - M Mejima
- Division of Mucosal Immunology, Department of Microbiology and Immunology, The Institute of Medical Science, The University of Tokyo, Tokyo, Japan
| | - K Ishige
- Biochemicals Division, Yamasa Corporation, Chiba, Japan
| | - K Akiyoshi
- Department of Polymer Chemistry, Graduate School of Engineering, Kyoto University, Kyoto, Japan.,Japan Science and Technology Agency (JST), The Exploratory Research for Advanced Technology (ERATO), Katura Int' Tech Center, Kyoto, Japan
| | - H Itoh
- Department of Internal Medicine, School of Medicine, Keio University, Tokyo, Japan
| | - H Kiyono
- Division of Mucosal Immunology, Department of Microbiology and Immunology, The Institute of Medical Science, The University of Tokyo, Tokyo, Japan.,International Research and Development Center for Mucosal Vaccines, The Institute of Medical Science, The University of Tokyo, Tokyo, Japan
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18
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The Role of Ghrelin and Ghrelin Signaling in Aging. Int J Mol Sci 2017; 18:ijms18071511. [PMID: 28704966 PMCID: PMC5536001 DOI: 10.3390/ijms18071511] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2017] [Revised: 07/04/2017] [Accepted: 07/07/2017] [Indexed: 01/20/2023] Open
Abstract
With our aging society, more people hope for a long and healthy life. In recent years, researchers have focused on healthy longevity factors. In particular, calorie restriction delays aging, reduces mortality, and extends life. Ghrelin, which is secreted during fasting, is well known as an orexigenic peptide. Because ghrelin is increased by caloric restriction, ghrelin may play an important role in the mechanism of longevity mediated by calorie restriction. In this review, we will discuss the role of orexigenic peptides with a particular focus on ghrelin. We conclude that the ghrelin-growth hormone secretagogue-R signaling pathway may play an important role in the anti-aging mechanism.
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19
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Liu L, Yang J, Qian F, Lu C. Hypothalamic-pituitary-adrenal axis hypersensitivity in female rats on a post-weaning high-fat diet after chronic mild stress. Exp Ther Med 2017; 14:439-446. [PMID: 28672951 PMCID: PMC5488418 DOI: 10.3892/etm.2017.4498] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/06/2016] [Accepted: 12/23/2016] [Indexed: 12/28/2022] Open
Abstract
A high-fat diet (HFD) is highly correlated to obesity, metabolic diseases and certain behavioral changes. However, the effects of post-weaning HFD in rats during puberty and the role of the hypothalamic-pituitary-adrenal (HPA) axis in this process have remained elusive. The present study hypothesized that the HPA axis mediates the behavioral alterations induced by a post-weaning HFD. To investigate this, female rats were divided into two groups, one of which was fed a HFD from postnatal weeks (PWs) 4-12, while the other group received standard chow. Rats in each group were then subdivided into two subgroups each, and from PW 9-12, animals from one of the two subgroups were subjected to chronic mild stress (CMS), while the other subgroup received no stress. At PW 12, the body weight of rats receiving a HFD but no DMS was significantly higher than that in the control group. The frequency of crossing and rearing in the open field test and the time in the center of the Y-maze were decreased following CMS. Total time to escape was decreased in rats receiving HFD and after CMS. The serum levels of adrenocorticotropic hormone and corticosterone were increased in rats receiving an HFD and after CMS, and the mRNA levels of corticotropin-releasing hormone and arginine vasopressin in the hypothalamus were increased in the HFD + CMS group compared to that in the control group. The mRNA expression of glucocorticoid receptor (GR) in the hippocampi of rats in the HFD + CMS group was significantly decreased and the mineralocorticoid receptor/GR ratio was increased compared to that in the groups receiving either CMS or a HFD. In conclusion, these results indicated that female rats fed a post-weaning HFD showed HPA axis hypersensitivity under CMS, which may mediate behavioral alterations.
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Affiliation(s)
- Lian Liu
- Department of Pharmacology, Medical School of Yangtze University, Jingzhou, Hubei 434023, P.R. China
- Laboratory of Neuronal and Brain Disease Modulation, Yangtze University, Jingzhou, Hubei 434023, P.R. China
| | - Junqiang Yang
- Department of Pharmacology, Medical School of Yangtze University, Jingzhou, Hubei 434023, P.R. China
- Laboratory of Neuronal and Brain Disease Modulation, Yangtze University, Jingzhou, Hubei 434023, P.R. China
| | - Feng Qian
- Laboratory of Neuronal and Brain Disease Modulation, Yangtze University, Jingzhou, Hubei 434023, P.R. China
- Department of Physiology, Medical School of Yangtze University, Jingzhou, Hubei 434023, P.R. China
| | - Chengbiao Lu
- Laboratory of Neuronal and Brain Disease Modulation, Yangtze University, Jingzhou, Hubei 434023, P.R. China
- Department of Physiology, Medical School of Yangtze University, Jingzhou, Hubei 434023, P.R. China
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20
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Exploring the Behavioral and Metabolic Phenotype Generated by Re-Introduction of the Ghrelin Receptor in the Ventral Tegmental Area. Int J Mol Sci 2017; 18:ijms18050914. [PMID: 28445429 PMCID: PMC5454827 DOI: 10.3390/ijms18050914] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2017] [Revised: 04/01/2017] [Accepted: 04/20/2017] [Indexed: 11/16/2022] Open
Abstract
Ghrelin receptor (Ghr-R) signaling in neurons of the ventral tegmental area (VTA) can modulate dopaminergic function and the reward-related effects of both palatable foods and drugs of abuse. In this study, we re-introduced the Ghr-R in VTA neurons in Ghr-R knockout mice (Ghr-RVTA mice) to specifically study the importance of the constitutively active Ghr-R for VTA neuronal signaling. Our results showed that re-introduction of the Ghr-R in the VTA had no impact on body weight or food intake under basal conditions. However, during novel environment stress Ghr-RVTA mice showed increased food intake and energy expenditure compared to Ghr-R knockout mice, demonstrating the significance of Ghr-R signaling in the response to stress. Ghr-RVTA mice also showed increased cocaine-induced locomotor activity compared to Ghr-R knockout mice, highlighting the importance of ghrelin signaling for the reward-related effects of activation of VTA neurons. Overall, our data suggest that re-introduction of the Ghr-R in the mesolimbic reward system of Ghr-R knockout mice increases the level of activation induced by both cocaine and novelty stress.
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21
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Effect of Xiaoyao San on the brain-gut axis in rats after chronic immobilization stress. JOURNAL OF TRADITIONAL CHINESE MEDICAL SCIENCES 2017. [DOI: 10.1016/j.jtcms.2017.09.005] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
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22
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Neonatal overfeeding disrupts pituitary ghrelin signalling in female rats long-term; Implications for the stress response. PLoS One 2017; 12:e0173498. [PMID: 28282447 PMCID: PMC5345806 DOI: 10.1371/journal.pone.0173498] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2017] [Accepted: 02/21/2017] [Indexed: 11/19/2022] Open
Abstract
The hypothalamic-pituitary-adrenal (HPA) axis responses to psychological stress are exacerbated in adult female but not male rats made obese due to overfeeding in early life. Ghrelin, traditionally known for its role in energy homeostasis, has been recently recognised for its role in coordinating the HPA responses to stress, particularly by acting directly at the anterior pituitary where the growth hormone secretagogue receptor (GHSR), the receptor for acyl ghrelin, is abundantly expressed. We therefore hypothesised that neonatal overfeeding in female rats would compromise pituitary responsiveness to ghrelin, contributing to a hyperactive central stress responsiveness. Unlike in males where hypothalamic ghrelin signalling is compromised by neonatal overfeeding, there was no effect of early life diet on circulating ghrelin or hypothalamic ghrelin signalling in females, indicating hypothalamic feeding and metabolic ghrelin circuitry remains intact. However, neonatal overfeeding did lead to long-term alterations in the pituitary ghrelin system. The neonatally overfed females had increased neonatal and reduced adult expression of GHSR and ghrelin-O-acyl transferase (GOAT) in the pituitary as well as reduced pituitary responsiveness to exogenous acyl ghrelin-induced adrenocorticotropic hormone (ACTH) release in vitro. These data suggest that neonatal overfeeding dysregulates pituitary ghrelin signalling long-term in females, potentially accounting for the hyper-responsive HPA axis in these animals. These findings have implications for how females may respond to stress throughout life, suggesting the way ghrelin modifies the stress response at the level of the pituitary may be less efficient in the neonatally overfed.
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23
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Huang HJ, Zhu XC, Han QQ, Wang YL, Yue N, Wang J, Yu R, Li B, Wu GC, Liu Q, Yu J. Ghrelin alleviates anxiety- and depression-like behaviors induced by chronic unpredictable mild stress in rodents. Behav Brain Res 2017; 326:33-43. [PMID: 28245976 DOI: 10.1016/j.bbr.2017.02.040] [Citation(s) in RCA: 58] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2016] [Revised: 02/18/2017] [Accepted: 02/22/2017] [Indexed: 12/31/2022]
Abstract
As a regulator of food intake, ghrelin also plays a key role in mood disorders. Previous studies reported that acute ghrelin administration defends against depressive symptoms of chronic stress. However, the effects of long-term ghrelin on rodents under chronic stress hasn't been revealed. In this study, we found chronic peripheral administration of ghrelin (5nmol/kg/day for 2 weeks, i.p.) could alleviate anxiety- and depression-like behaviors induced by chronic unpredictable mild stress (CUMS). The depression-like behaviors were assessed by the forced swimming test (FST), and anxiety-like behaviors were assessed by the open field test (OFT) and the elevated plus maze test (EPM). Meanwhile, we observed that peripheral acylated ghrelin, together with gastral and hippocampal ghrelin prepropeptide mRNA level, were significantly up-regulated in CUMS mice. Besides, the increased protein level of growth hormone secretagogue receptor (GHSR) in hippocampus were also detected. These results suggested that the endogenous ghrelin/GHSR pathway activated by CUMS plays a role in homeostasis. Further results showed that central treatment of ghrelin (10μg/rat/day for 2 weeks, i.c.v.) or GHRP-6 (the agonist of GHSR, 10μg/rat/day for 2 weeks, i.c.v.) significantly alleviated the depression-like behaviors induced by CUMS in FST and sucrose preference test (SPT). Based on these results, we concluded that central GHSR is involved in the antidepressant-like effect of exogenous ghrelin treatment, and ghrelin/GHSR may have the inherent neuromodulatory properties against depressive symptoms.
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Affiliation(s)
- Hui-Jie Huang
- Department of Integrative Medicine and Neurobiology, State Key Lab of Medical Neurobiology, Institutes of Brain Science, Shanghai Medical College, Fudan University, Shanghai 200032, China
| | - Xiao-Cang Zhu
- Department of Integrative Medicine and Neurobiology, State Key Lab of Medical Neurobiology, Institutes of Brain Science, Shanghai Medical College, Fudan University, Shanghai 200032, China
| | - Qiu-Qin Han
- Department of Integrative Medicine and Neurobiology, State Key Lab of Medical Neurobiology, Institutes of Brain Science, Shanghai Medical College, Fudan University, Shanghai 200032, China
| | - Ya-Lin Wang
- Department of Integrative Medicine and Neurobiology, State Key Lab of Medical Neurobiology, Institutes of Brain Science, Shanghai Medical College, Fudan University, Shanghai 200032, China
| | - Na Yue
- Department of Integrative Medicine and Neurobiology, State Key Lab of Medical Neurobiology, Institutes of Brain Science, Shanghai Medical College, Fudan University, Shanghai 200032, China
| | - Jing Wang
- Department of Integrative Medicine and Neurobiology, State Key Lab of Medical Neurobiology, Institutes of Brain Science, Shanghai Medical College, Fudan University, Shanghai 200032, China
| | - Rui Yu
- Department of Integrative Medicine and Neurobiology, State Key Lab of Medical Neurobiology, Institutes of Brain Science, Shanghai Medical College, Fudan University, Shanghai 200032, China
| | - Bing Li
- Center Laboratory, Jinshan Hospital of Fudan University, Shanghai 201508, China
| | - Gen-Cheng Wu
- Department of Integrative Medicine and Neurobiology, State Key Lab of Medical Neurobiology, Institutes of Brain Science, Shanghai Medical College, Fudan University, Shanghai 200032, China
| | - Qiong Liu
- Department of Anatomy, Histology and Embryology, Shanghai Medical College, Fudan University, Shanghai, China; Key Laboratory of Medical Imaging Computing and Computer Assisted Intervention of Shanghai, Shanghai 200032, China.
| | - Jin Yu
- Department of Integrative Medicine and Neurobiology, State Key Lab of Medical Neurobiology, Institutes of Brain Science, Shanghai Medical College, Fudan University, Shanghai 200032, China.
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24
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Fulcher N, Tran S, Shams S, Chatterjee D, Gerlai R. Neurochemical and Behavioral Responses to Unpredictable Chronic Mild Stress Following Developmental Isolation: The Zebrafish as a Model for Major Depression. Zebrafish 2017; 14:23-34. [DOI: 10.1089/zeb.2016.1295] [Citation(s) in RCA: 56] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Affiliation(s)
- Niveen Fulcher
- Department of Psychology, University of Toronto Mississauga, Mississauga, Canada
| | - Steven Tran
- Department of Cell and Systems Biology, University of Toronto, Toronto, Canada
| | - Soaleha Shams
- Department of Cell and Systems Biology, University of Toronto, Toronto, Canada
| | - Diptendu Chatterjee
- Department of Psychology, University of Toronto Mississauga, Mississauga, Canada
| | - Robert Gerlai
- Department of Psychology, University of Toronto Mississauga, Mississauga, Canada
- Department of Cell and Systems Biology, University of Toronto, Toronto, Canada
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25
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Toufexis DJ, Lipatova O, Johnson AC, Abizaid A. Food-Restriction Lowers the Acoustic Startle Response in both Male and Female Rats, and, in Combination with Acute Ghrelin Injection, Abolishes the Expression of Fear-Potentiated Startle in Male Rats. J Neuroendocrinol 2016; 28. [PMID: 27754564 DOI: 10.1111/jne.12436] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/14/2016] [Revised: 09/20/2016] [Accepted: 10/15/2016] [Indexed: 12/15/2022]
Abstract
Food restriction has been reported to reduce anxiety-like behaviour in male rats, whereas the effects of food restriction on anxiety in female rats are less clear. Ghrelin is a peptide hormone produced and secreted in the stomach that stimulates food intake and is considered to play a role in reward and emotional responses such as fear expression. Under food restriction, endogenous ghrelin levels increase. In the present study, we examined the effect of moderate food restriction (80% of ad libitum fed weight), with or without an acute application of a small dose of exogenous ghrelin intended to cause an immediate hunger response, on the expression of the acoustic startle reflex (ASR). This was carried out under basal conditions (baseline ASR to 90- and 95-dB noise bursts), and in the presence of a light cue associated with a mild foot-shock, as measured by fear-potentiated startle, which compares the proportional change in ASR in the presence of the conditioned stimulus. The results obtained show that food-restriction reduces basal ASR in both male and female rats, apart from any concomitant change in motor activity, suggesting that food-restriction reduces anxiety levels in both sexes. In addition, the data show that food-restriction reduces fear-potentiated startle in male but not female rats. Acute ghrelin injection, prior to fear-potentiated startle testing, eliminates the expression of fear-potentiated startle in food-restricted male rats alone, suggesting a role for ghrelin in the reduction of fear expression in food-restricted male rats. These data imply that, although food-restriction decreases anxiety in both sexes, learned fear responses remain intact after food-restriction in female but not male rats.
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Affiliation(s)
- D J Toufexis
- Department of Psychological Science, University of Vermont, Burlington, VT, USA
| | - O Lipatova
- Department of Psychology, Christopher Newport University, Newport News, VA, USA
| | - A C Johnson
- Department of Neurological Sciences, University of Vermont, Burlington, VT, USA
| | - A Abizaid
- Alfonso Abizaid, Department of Neuroscience, Carlton University, Ottawa, Canada
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Stark R, Santos VV, Geenen B, Cabral A, Dinan T, Bayliss JA, Lockie SH, Reichenbach A, Lemus MB, Perello M, Spencer SJ, Kozicz T, Andrews ZB. Des-Acyl Ghrelin and Ghrelin O-Acyltransferase Regulate Hypothalamic-Pituitary-Adrenal Axis Activation and Anxiety in Response to Acute Stress. Endocrinology 2016; 157:3946-3957. [PMID: 27490185 DOI: 10.1210/en.2016-1306] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
Ghrelin exists in two forms in circulation, acyl ghrelin and des-acyl ghrelin, both of which have distinct and fundamental roles in a variety of physiological functions. Despite this fact, a large proportion of papers simply measure and refer to plasma ghrelin without specifying the acylation status. It is therefore critical to assess and state the acylation status of plasma ghrelin in all studies. In this study we tested the effect of des-acyl ghrelin administration on the hypothalamic-pituitary-adrenal axis and on anxiety-like behavior of mice lacking endogenous ghrelin and in ghrelin-O-acyltransferase (GOAT) knockout (KO) mice that have no endogenous acyl ghrelin and high endogenous des-acyl ghrelin. Our results show des-acyl ghrelin produces an anxiogenic effect under nonstressed conditions, but this switches to an anxiolytic effect under stress. Des-acyl ghrelin influences plasma corticosterone under both nonstressed and stressed conditions, although c-fos activation in the paraventricular nucleus of the hypothalamus is not different. By contrast, GOAT KO are anxious under both nonstressed and stressed conditions, although this is not due to corticosterone release from the adrenals but rather from impaired feedback actions in the paraventricular nucleus of the hypothalamus, as assessed by c-fos activation. These results reveal des-acyl ghrelin treatment and GOAT deletion have differential effects on the hypothalamic-pituitary-adrenal axis and anxiety-like behavior, suggesting that anxiety-like behavior in GOAT KO mice is not due to high plasma des-acyl ghrelin.
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Affiliation(s)
- Romana Stark
- Monash Biomedicine Discovery Institute and Department of Physiology (R.S., V.V.S., J.A.B., S.H.L., A.R., M.B.L., Z.B.A.), Monash University, Clayton, Australia Monash University, Clayton, Melbourne, Victoria 3800, Australia; Department of Anatomy (B.G.M T.K.), Radboud University Medical Center, 6500HB Nijmegen, The Netherlands; Laboratory of Neurophysiology (A.C., M.P.) Multidisciplinary Institute of Cell Biology (Argentine Research Council [CONICET] and Scientific Research Commission, Province of Buenos Aires [CIC-PBA]), La Plata, Buenos Aires, Argentina; School of Health and Biomedical Sciences (T.D., S.J.S.), RMIT University, Melbourne, Victoria 3083, Australia; and Hayward Genetics Center (T.K.), Tulane University, New Orleans, Louisiana 70112
| | - Vanessa V Santos
- Monash Biomedicine Discovery Institute and Department of Physiology (R.S., V.V.S., J.A.B., S.H.L., A.R., M.B.L., Z.B.A.), Monash University, Clayton, Australia Monash University, Clayton, Melbourne, Victoria 3800, Australia; Department of Anatomy (B.G.M T.K.), Radboud University Medical Center, 6500HB Nijmegen, The Netherlands; Laboratory of Neurophysiology (A.C., M.P.) Multidisciplinary Institute of Cell Biology (Argentine Research Council [CONICET] and Scientific Research Commission, Province of Buenos Aires [CIC-PBA]), La Plata, Buenos Aires, Argentina; School of Health and Biomedical Sciences (T.D., S.J.S.), RMIT University, Melbourne, Victoria 3083, Australia; and Hayward Genetics Center (T.K.), Tulane University, New Orleans, Louisiana 70112
| | - Bram Geenen
- Monash Biomedicine Discovery Institute and Department of Physiology (R.S., V.V.S., J.A.B., S.H.L., A.R., M.B.L., Z.B.A.), Monash University, Clayton, Australia Monash University, Clayton, Melbourne, Victoria 3800, Australia; Department of Anatomy (B.G.M T.K.), Radboud University Medical Center, 6500HB Nijmegen, The Netherlands; Laboratory of Neurophysiology (A.C., M.P.) Multidisciplinary Institute of Cell Biology (Argentine Research Council [CONICET] and Scientific Research Commission, Province of Buenos Aires [CIC-PBA]), La Plata, Buenos Aires, Argentina; School of Health and Biomedical Sciences (T.D., S.J.S.), RMIT University, Melbourne, Victoria 3083, Australia; and Hayward Genetics Center (T.K.), Tulane University, New Orleans, Louisiana 70112
| | - Agustina Cabral
- Monash Biomedicine Discovery Institute and Department of Physiology (R.S., V.V.S., J.A.B., S.H.L., A.R., M.B.L., Z.B.A.), Monash University, Clayton, Australia Monash University, Clayton, Melbourne, Victoria 3800, Australia; Department of Anatomy (B.G.M T.K.), Radboud University Medical Center, 6500HB Nijmegen, The Netherlands; Laboratory of Neurophysiology (A.C., M.P.) Multidisciplinary Institute of Cell Biology (Argentine Research Council [CONICET] and Scientific Research Commission, Province of Buenos Aires [CIC-PBA]), La Plata, Buenos Aires, Argentina; School of Health and Biomedical Sciences (T.D., S.J.S.), RMIT University, Melbourne, Victoria 3083, Australia; and Hayward Genetics Center (T.K.), Tulane University, New Orleans, Louisiana 70112
| | - Tara Dinan
- Monash Biomedicine Discovery Institute and Department of Physiology (R.S., V.V.S., J.A.B., S.H.L., A.R., M.B.L., Z.B.A.), Monash University, Clayton, Australia Monash University, Clayton, Melbourne, Victoria 3800, Australia; Department of Anatomy (B.G.M T.K.), Radboud University Medical Center, 6500HB Nijmegen, The Netherlands; Laboratory of Neurophysiology (A.C., M.P.) Multidisciplinary Institute of Cell Biology (Argentine Research Council [CONICET] and Scientific Research Commission, Province of Buenos Aires [CIC-PBA]), La Plata, Buenos Aires, Argentina; School of Health and Biomedical Sciences (T.D., S.J.S.), RMIT University, Melbourne, Victoria 3083, Australia; and Hayward Genetics Center (T.K.), Tulane University, New Orleans, Louisiana 70112
| | - Jacqueline A Bayliss
- Monash Biomedicine Discovery Institute and Department of Physiology (R.S., V.V.S., J.A.B., S.H.L., A.R., M.B.L., Z.B.A.), Monash University, Clayton, Australia Monash University, Clayton, Melbourne, Victoria 3800, Australia; Department of Anatomy (B.G.M T.K.), Radboud University Medical Center, 6500HB Nijmegen, The Netherlands; Laboratory of Neurophysiology (A.C., M.P.) Multidisciplinary Institute of Cell Biology (Argentine Research Council [CONICET] and Scientific Research Commission, Province of Buenos Aires [CIC-PBA]), La Plata, Buenos Aires, Argentina; School of Health and Biomedical Sciences (T.D., S.J.S.), RMIT University, Melbourne, Victoria 3083, Australia; and Hayward Genetics Center (T.K.), Tulane University, New Orleans, Louisiana 70112
| | - Sarah H Lockie
- Monash Biomedicine Discovery Institute and Department of Physiology (R.S., V.V.S., J.A.B., S.H.L., A.R., M.B.L., Z.B.A.), Monash University, Clayton, Australia Monash University, Clayton, Melbourne, Victoria 3800, Australia; Department of Anatomy (B.G.M T.K.), Radboud University Medical Center, 6500HB Nijmegen, The Netherlands; Laboratory of Neurophysiology (A.C., M.P.) Multidisciplinary Institute of Cell Biology (Argentine Research Council [CONICET] and Scientific Research Commission, Province of Buenos Aires [CIC-PBA]), La Plata, Buenos Aires, Argentina; School of Health and Biomedical Sciences (T.D., S.J.S.), RMIT University, Melbourne, Victoria 3083, Australia; and Hayward Genetics Center (T.K.), Tulane University, New Orleans, Louisiana 70112
| | - Alex Reichenbach
- Monash Biomedicine Discovery Institute and Department of Physiology (R.S., V.V.S., J.A.B., S.H.L., A.R., M.B.L., Z.B.A.), Monash University, Clayton, Australia Monash University, Clayton, Melbourne, Victoria 3800, Australia; Department of Anatomy (B.G.M T.K.), Radboud University Medical Center, 6500HB Nijmegen, The Netherlands; Laboratory of Neurophysiology (A.C., M.P.) Multidisciplinary Institute of Cell Biology (Argentine Research Council [CONICET] and Scientific Research Commission, Province of Buenos Aires [CIC-PBA]), La Plata, Buenos Aires, Argentina; School of Health and Biomedical Sciences (T.D., S.J.S.), RMIT University, Melbourne, Victoria 3083, Australia; and Hayward Genetics Center (T.K.), Tulane University, New Orleans, Louisiana 70112
| | - Moyra B Lemus
- Monash Biomedicine Discovery Institute and Department of Physiology (R.S., V.V.S., J.A.B., S.H.L., A.R., M.B.L., Z.B.A.), Monash University, Clayton, Australia Monash University, Clayton, Melbourne, Victoria 3800, Australia; Department of Anatomy (B.G.M T.K.), Radboud University Medical Center, 6500HB Nijmegen, The Netherlands; Laboratory of Neurophysiology (A.C., M.P.) Multidisciplinary Institute of Cell Biology (Argentine Research Council [CONICET] and Scientific Research Commission, Province of Buenos Aires [CIC-PBA]), La Plata, Buenos Aires, Argentina; School of Health and Biomedical Sciences (T.D., S.J.S.), RMIT University, Melbourne, Victoria 3083, Australia; and Hayward Genetics Center (T.K.), Tulane University, New Orleans, Louisiana 70112
| | - Mario Perello
- Monash Biomedicine Discovery Institute and Department of Physiology (R.S., V.V.S., J.A.B., S.H.L., A.R., M.B.L., Z.B.A.), Monash University, Clayton, Australia Monash University, Clayton, Melbourne, Victoria 3800, Australia; Department of Anatomy (B.G.M T.K.), Radboud University Medical Center, 6500HB Nijmegen, The Netherlands; Laboratory of Neurophysiology (A.C., M.P.) Multidisciplinary Institute of Cell Biology (Argentine Research Council [CONICET] and Scientific Research Commission, Province of Buenos Aires [CIC-PBA]), La Plata, Buenos Aires, Argentina; School of Health and Biomedical Sciences (T.D., S.J.S.), RMIT University, Melbourne, Victoria 3083, Australia; and Hayward Genetics Center (T.K.), Tulane University, New Orleans, Louisiana 70112
| | - Sarah J Spencer
- Monash Biomedicine Discovery Institute and Department of Physiology (R.S., V.V.S., J.A.B., S.H.L., A.R., M.B.L., Z.B.A.), Monash University, Clayton, Australia Monash University, Clayton, Melbourne, Victoria 3800, Australia; Department of Anatomy (B.G.M T.K.), Radboud University Medical Center, 6500HB Nijmegen, The Netherlands; Laboratory of Neurophysiology (A.C., M.P.) Multidisciplinary Institute of Cell Biology (Argentine Research Council [CONICET] and Scientific Research Commission, Province of Buenos Aires [CIC-PBA]), La Plata, Buenos Aires, Argentina; School of Health and Biomedical Sciences (T.D., S.J.S.), RMIT University, Melbourne, Victoria 3083, Australia; and Hayward Genetics Center (T.K.), Tulane University, New Orleans, Louisiana 70112
| | - Tamas Kozicz
- Monash Biomedicine Discovery Institute and Department of Physiology (R.S., V.V.S., J.A.B., S.H.L., A.R., M.B.L., Z.B.A.), Monash University, Clayton, Australia Monash University, Clayton, Melbourne, Victoria 3800, Australia; Department of Anatomy (B.G.M T.K.), Radboud University Medical Center, 6500HB Nijmegen, The Netherlands; Laboratory of Neurophysiology (A.C., M.P.) Multidisciplinary Institute of Cell Biology (Argentine Research Council [CONICET] and Scientific Research Commission, Province of Buenos Aires [CIC-PBA]), La Plata, Buenos Aires, Argentina; School of Health and Biomedical Sciences (T.D., S.J.S.), RMIT University, Melbourne, Victoria 3083, Australia; and Hayward Genetics Center (T.K.), Tulane University, New Orleans, Louisiana 70112
| | - Zane B Andrews
- Monash Biomedicine Discovery Institute and Department of Physiology (R.S., V.V.S., J.A.B., S.H.L., A.R., M.B.L., Z.B.A.), Monash University, Clayton, Australia Monash University, Clayton, Melbourne, Victoria 3800, Australia; Department of Anatomy (B.G.M T.K.), Radboud University Medical Center, 6500HB Nijmegen, The Netherlands; Laboratory of Neurophysiology (A.C., M.P.) Multidisciplinary Institute of Cell Biology (Argentine Research Council [CONICET] and Scientific Research Commission, Province of Buenos Aires [CIC-PBA]), La Plata, Buenos Aires, Argentina; School of Health and Biomedical Sciences (T.D., S.J.S.), RMIT University, Melbourne, Victoria 3083, Australia; and Hayward Genetics Center (T.K.), Tulane University, New Orleans, Louisiana 70112
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Ghrelin's Role in the Hypothalamic-Pituitary-Adrenal Axis Stress Response: Implications for Mood Disorders. Biol Psychiatry 2015; 78:19-27. [PMID: 25534754 DOI: 10.1016/j.biopsych.2014.10.021] [Citation(s) in RCA: 90] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/21/2014] [Revised: 09/26/2014] [Accepted: 10/15/2014] [Indexed: 12/24/2022]
Abstract
Ghrelin is a stomach hormone normally associated with feeding behavior and energy homeostasis. Recent studies highlight that ghrelin targets the brain to regulate a diverse number of functions, including learning, memory, motivation, stress responses, anxiety, and mood. In this review, we discuss recent animal and human studies showing that ghrelin regulates the hypothalamic-pituitary-adrenal axis and affects anxiety and mood disorders, such as depression and fear. We address the neural sites of action through which ghrelin regulates the hypothalamic-pituitary-adrenal axis and associated stress-induced behaviors, including the centrally projecting Edinger-Westphal nucleus, the hippocampus, amygdala, locus coeruleus, and the ventral tegmental area. Stressors modulate many behaviors associated with motivation, fear, anxiety, depression, and appetite; therefore, we assess the potential role for ghrelin as a stress feedback signal that regulates these associated behaviors. Finally, we briefly discuss important areas for future research that will help us move closer to potential ghrelin-based therapies to treat stress responses and related disorders.
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Growth Hormone Secretagogue Receptor Dimers: A New Pharmacological Target. eNeuro 2015; 2:eN-REV-0053-14. [PMID: 26464979 PMCID: PMC4596092 DOI: 10.1523/eneuro.0053-14.2015] [Citation(s) in RCA: 60] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2014] [Revised: 03/25/2015] [Accepted: 04/07/2015] [Indexed: 01/04/2023] Open
Abstract
The growth hormone secretagogue receptor (GHSR1a), the target of the ghrelin peptide, is widely distributed throughout the brain, and, while studies have often reported very low or absent levels of central ghrelin, it is now known that GHSR1a, even in the absence of a natural ligand, has physiological roles. Not only do these roles originate from the receptor's constitutive activity, but recent data indicate that GHSR1a dimerizes with a wide array of other receptors. These include the dopamine 1 receptor (D1R), the dopamine 2 receptor (D2R), the melanocortin-3 receptor (MC3R), the serotonin 2C receptor (5-HT2C), and possibly the cannabinoid type 1 receptor (CB1). Within these dimers, signaling of the protomers involved are modified through facilitation, inhibition, and even modification of signaling pathways resulting in physiological consequences not seen in the absence of these dimers. While in some cases the ghrelin peptide is not required for these modifications to occur, in others, the presence is necessary for these changes to take effect. These heterodimers demonstrate the broad array of roles and complexity of the ghrelin system. By better understanding how these dimers work, it is hoped that improved treatments for a variety of disorders, including Parkinson's disease, schizophrenia, addiction, obesity, diabetes, and more, can be devised. In this review, we examine the current state of knowledge surrounding GHSR heterodimers, and how we can apply this knowledge to various pharmacological treatments.
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The P7C3 class of neuroprotective compounds exerts antidepressant efficacy in mice by increasing hippocampal neurogenesis. Mol Psychiatry 2015; 20:500-8. [PMID: 24751964 PMCID: PMC4206684 DOI: 10.1038/mp.2014.34] [Citation(s) in RCA: 114] [Impact Index Per Article: 12.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/12/2013] [Revised: 02/13/2014] [Accepted: 02/26/2014] [Indexed: 12/13/2022]
Abstract
Augmenting hippocampal neurogenesis represents a potential new strategy for treating depression. Here we test this possibility by comparing hippocampal neurogenesis in depression-prone ghrelin receptor (Ghsr)-null mice to that in wild-type littermates and by determining the antidepressant efficacy of the P7C3 class of neuroprotective compounds. Exposure of Ghsr-null mice to chronic social defeat stress (CSDS) elicits more severe depressive-like behavior than in CSDS-exposed wild-type littermates, and exposure of Ghsr-null mice to 60% caloric restriction fails to elicit antidepressant-like behavior. CSDS resulted in more severely reduced cell proliferation and survival in the ventral dentate gyrus (DG) subgranular zone of Ghsr-null mice than in that of wild-type littermates. Also, caloric restriction increased apoptosis of DG subgranular zone cells in Ghsr-null mice, although it had the opposite effect in wild-type littermates. Systemic treatment with P7C3 during CSDS increased survival of proliferating DG cells, which ultimately developed into mature (NeuN+) neurons. Notably, P7C3 exerted a potent antidepressant-like effect in Ghsr-null mice exposed to either CSDS or caloric restriction, while the more highly active analog P7C3-A20 also exerted an antidepressant-like effect in wild-type littermates. Focal ablation of hippocampal stem cells with radiation eliminated this antidepressant effect, further attributing the P7C3 class antidepressant effect to its neuroprotective properties and resultant augmentation of hippocampal neurogenesis. Finally, P7C3-A20 demonstrated greater proneurogenic efficacy than a wide spectrum of currently marketed antidepressant drugs. Taken together, our data confirm the role of aberrant hippocampal neurogenesis in the etiology of depression and suggest that the neuroprotective P7C3-compounds represent a novel strategy for treating patients with this disease.
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Ghrelin effects expression of several genes associated with depression-like behavior. Prog Neuropsychopharmacol Biol Psychiatry 2015; 56:227-34. [PMID: 25286107 DOI: 10.1016/j.pnpbp.2014.09.012] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/24/2014] [Revised: 09/23/2014] [Accepted: 09/23/2014] [Indexed: 02/03/2023]
Abstract
Ghrelin (Ghr) is an orexigenic peptide that is being investigated for its potential role in development of anxiety-like behavior and modulation of depressive-like symptoms induced by bilateral olfactory bulbectomy (OB) in rodents. Olfactory bulbectomy is an animal model useful to study of depression and Ghr could be an alternative therapeutic tool in depression therapy. We studied the effects of intracerebroventricular (i.c.v.) Ghr administration on the expression of hypothalamic genes related to depression and mood (delta opioid receptor (DOR), mu opioid receptor (MOR) and kappa opioid receptor (KOR), lutropin-choriogonadotropic hormone receptor (LHCGR), serotonin transporter (SERT), interleukin 1 beta (IL-1b), vasopressin (AVP) and corticotrophin releasing hormone (CRH)) in OB animals, as well as changes in plasma levels of AVP, CRH and adenocorticotropic hormone (ACTH). We found that acute Ghr 0.3 nmol/μl administration increases gene expression of DOR, SERT and LHCGR in OB mice and decreased expression of IL-1b, suggesting that these genes could be involved in the antidepressant-like effects of Ghr. In addition, OB animals exhibit high AVP gene expression and elevated plasma concentrations of AVP and ACTH and acute Ghr 0.3 nmol/μl administration reduces AVP gene expression and the concentration of these hormones, suggesting that peptide-effects on depressive-like behavior could be mediated at least in part via AVP. In conclusion, this study provides new evidence about genes, receptors and hormones involved in the antidepressant mechanism/s induced by Ghr in OB animals.
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Wellman MK, Patterson ZR, MacKay H, Darling JE, Mani BK, Zigman JM, Hougland JL, Abizaid A. Novel Regulator of Acylated Ghrelin, CF801, Reduces Weight Gain, Rebound Feeding after a Fast, and Adiposity in Mice. Front Endocrinol (Lausanne) 2015; 6:144. [PMID: 26441834 PMCID: PMC4585333 DOI: 10.3389/fendo.2015.00144] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/19/2015] [Accepted: 09/01/2015] [Indexed: 01/04/2023] Open
Abstract
Ghrelin is a 28 amino acid hormonal peptide that is intimately related to the regulation of food intake and body weight. Once secreted, ghrelin binds to the growth hormone secretagogue receptor-1a, the only known receptor for ghrelin and is capable of activating a number of signaling cascades, ultimately resulting in an increase in food intake and adiposity. Because ghrelin has been linked to overeating and the development of obesity, a number of pharmacological interventions have been generated in order to interfere with either the activation of ghrelin or interrupting ghrelin signaling as a means to reducing appetite and decrease weight gain. Here, we present a novel peptide, CF801, capable of reducing circulating acylated ghrelin levels and subsequent body weight gain and adiposity. To this end, we show that IP administration of CF801 is sufficient to reduce circulating plasma acylated ghrelin levels. Acutely, intraperitoneal injections of CF801 resulted in decreased rebound feeding after an overnight fast. When delivered chronically, they decreased weight gain and adiposity without affecting caloric intake. CF801, however, did cause a change in diet preference, decreasing preference for a high-fat diet and increasing preference for regular chow diet. Given the complexity of ghrelin receptor function, we propose that CF801, along with other compounds that regulate ghrelin secretion, may prove to be a beneficial tool in the study of the ghrelin system, and potential targets for ghrelin-based obesity treatments without altering the function of ghrelin receptors.
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Affiliation(s)
| | | | - Harry MacKay
- Department of Neuroscience, Carleton University, Ottawa, ON, Canada
| | | | - Bharath K. Mani
- Department of Internal Medicine, Division of Hypothalamic Research, The University of Texas Southwestern Medical Center, Dallas, TX, USA
- Department of Internal Medicine, Division of Endocrinology and Metabolism, The University of Texas Southwestern Medical Center, Dallas, TX, USA
- Department of Psychiatry, The University of Texas Southwestern Medical Center, Dallas, TX, USA
| | - Jeffrey M. Zigman
- Department of Internal Medicine, Division of Hypothalamic Research, The University of Texas Southwestern Medical Center, Dallas, TX, USA
- Department of Internal Medicine, Division of Endocrinology and Metabolism, The University of Texas Southwestern Medical Center, Dallas, TX, USA
- Department of Psychiatry, The University of Texas Southwestern Medical Center, Dallas, TX, USA
| | | | - Alfonso Abizaid
- Department of Neuroscience, Carleton University, Ottawa, ON, Canada
- *Correspondence: Alfonso Abizaid, Department of Neuroscience, Carleton University, 1125 Colonel By Drive, 329 Life Science Research Building, Ottawa, ON K1S 5B6, Canada,
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Hardaway JA, Crowley NA, Bulik CM, Kash TL. Integrated circuits and molecular components for stress and feeding: implications for eating disorders. GENES, BRAIN, AND BEHAVIOR 2015; 14:85-97. [PMID: 25366309 PMCID: PMC4465370 DOI: 10.1111/gbb.12185] [Citation(s) in RCA: 37] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/19/2014] [Revised: 10/24/2014] [Accepted: 10/27/2014] [Indexed: 12/11/2022]
Abstract
Eating disorders are complex brain disorders that afflict millions of individuals worldwide. The etiology of these diseases is not fully understood, but a growing body of literature suggests that stress and anxiety may play a critical role in their development. As our understanding of the genetic and environmental factors that contribute to disease in clinical populations like anorexia nervosa, bulimia nervosa and binge eating disorder continue to grow, neuroscientists are using animal models to understand the neurobiology of stress and feeding. We hypothesize that eating disorder clinical phenotypes may result from stress-induced maladaptive alterations in neural circuits that regulate feeding, and that these circuits can be neurochemically isolated using animal model of eating disorders.
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Affiliation(s)
- J. A. Hardaway
- Bowles Alcohol Center, University of North Carolina at Chapel Hill, NC, USA
| | - N. A. Crowley
- Bowles Alcohol Center, University of North Carolina at Chapel Hill, NC, USA
| | - C. M. Bulik
- UNC Eating Disorders Program, University of North Carolina at Chapel Hill, NC, USA
| | - T. L. Kash
- Bowles Alcohol Center, University of North Carolina at Chapel Hill, NC, USA
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33
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Ghrelin: a link between ageing, metabolism and neurodegenerative disorders. Neurobiol Dis 2014; 72 Pt A:72-83. [PMID: 25173805 DOI: 10.1016/j.nbd.2014.08.026] [Citation(s) in RCA: 54] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2014] [Revised: 06/28/2014] [Accepted: 08/20/2014] [Indexed: 12/13/2022] Open
Abstract
Along with the increase in life expectancy over the last century comes the increased risk for development of age-related disorders, including metabolic and neurodegenerative diseases such as Alzheimer's, Parkinson's and Huntington's diseases. These chronic disorders share two main characteristics: 1) neuronal loss in motor, sensory or cognitive systems, leading to cognitive and motor decline; and 2) a strong correlation between metabolic changes and neurodegeneration. In order to treat them, a better understanding of their complexity is required: it is necessary to interpret the neuronal damage in light of the metabolic changes, and to find the disrupted link between the peripheral organs governing energy metabolism and the CNS. This review is an attempt to present ghrelin as part of molecular regulatory interface between energy metabolism, neuroendocrine and neurodegenerative processes. Ghrelin takes part in lipid and glucose metabolism, in higher brain functions such as sleep-wake state, learning and memory consolidation; it influences mitochondrial respiration and shows neuroprotective effect. All these make ghrelin an attractive target for development of biomarkers or therapeutics for prevention or treatment of disorders, in which cell protection and recruitment of new neurons or synapses are needed.
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Khan MSI, Kaiya H, Tachibana T. Central injection of urocortin-3 but not corticotrophin-releasing hormone influences the ghrelin/GHS-R1a system of the proventriculus and brain in chicks. Domest Anim Endocrinol 2014; 47:27-34. [PMID: 24484650 DOI: 10.1016/j.domaniend.2013.12.002] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/03/2013] [Revised: 12/20/2013] [Accepted: 12/29/2013] [Indexed: 11/18/2022]
Abstract
Ghrelin, the endogenous ligand for growth hormone secretagogue receptor 1a (GHS-R1a), stimulates food intake in mammals centrally and peripherally. In contrast, central injection of ghrelin inhibits feeding in neonatal chicks (Gallus gallus), which is thought to be mediated by the corticotrophin-releasing hormone (CRH) system, indicating that the mechanisms underlying ghrelin's action are different in chicks and mammals. However, the interaction between the ghrelin system and the CRH system has not been fully clarified in chicks. In the present study, we examined the effect of intracerebroventricular (ICV) injection of CRH and urocortin-3 (UCN-3), a CRH family peptide and an endogenous ligand for the CRH type-2 receptor (CRH-R2), on synthesis and secretion of ghrelin in chicks. Intracerebroventricular injection of UCN-3 but not CRH increased plasma ghrelin concentration (P < 0.05), diencephalic mRNA expression of ghrelin, and GHS-R1a (P < 0.05) and tended to decrease ghrelin (P = 0.08) and GHS-R1a (P = 0.10) mRNA expression in the proventriculus. Moreover, ICV injection of UCN-3 tended to increase diencephalic mRNA expression of CRH-R2 (P = 0.08) and CRH had no effect on it. In addition, ICV injection of CRH but not UCN-3 increased plasma corticosterone concentration (P < 0.05) and decreased the diencephalic mRNA expression of CRH-R1 (P < 0.05). These results clearly indicate that the roles of the CRH system for the ghrelin system are divided. The present study suggests that UCN-3 is mainly involved in the ghrelin system in chicks perhaps through the CRH-R2.
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Affiliation(s)
- M S I Khan
- Department of Agrobiological Science, Faculty of Agriculture, Ehime University, Matsuyama 790-8566, Japan.
| | - H Kaiya
- Department of Biochemistry, National Cerebral and Cardiovascular Center Research Institute, 5-7-1 Fujishirodai, Suita, Osaka 565-8565, Japan
| | - T Tachibana
- Department of Agrobiological Science, Faculty of Agriculture, Ehime University, Matsuyama 790-8566, Japan
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Hansson C, Alvarez-Crespo M, Taube M, Skibicka KP, Schmidt L, Karlsson-Lindahl L, Egecioglu E, Nissbrandt H, Dickson SL. Influence of ghrelin on the central serotonergic signaling system in mice. Neuropharmacology 2014; 79:498-505. [DOI: 10.1016/j.neuropharm.2013.12.012] [Citation(s) in RCA: 40] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2013] [Revised: 11/22/2013] [Accepted: 12/14/2013] [Indexed: 02/09/2023]
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Douglas GAF, McGirr R, Charlton CL, Kagan DB, Hoffman LM, Luyt LG, Dhanvantari S. Characterization of a far-red analog of ghrelin for imaging GHS-R in P19-derived cardiomyocytes. Peptides 2014; 54:81-8. [PMID: 24468548 DOI: 10.1016/j.peptides.2014.01.011] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/09/2013] [Revised: 01/16/2014] [Accepted: 01/16/2014] [Indexed: 11/29/2022]
Abstract
Ghrelin and its receptor, the growth hormone secretagogue receptor (GHS-R), are expressed in the heart, and may function to promote cardiomyocyte survival, differentiation and contractility. Previously, we had generated a truncated analog of ghrelin conjugated to fluorescein isothiocyanate for the purposes of determining GHS-R expression in situ. We now report the generation and characterization of a far-red ghrelin analog, [Dpr(3)(octanoyl), Lys(19)(Cy5)]ghrelin (1-19), and show that it can be used to image changes in GHS-R in developing cardiomyocytes. We also generated the des-acyl analog, des-acyl [Lys(19)(Cy5)]ghrelin (1-19) and characterized its binding to mouse heart sections. Receptor binding affinity of Cy5-ghrelin as measured in HEK293 cells overexpressing GHS-R1a was within an order of magnitude of that of fluorescein-ghrelin and native human ghrelin, while the des-acyl Cy5-ghrelin did not bind GHS-R1a. Live cell imaging in HEK293/GHS-R1a cells showed cell surface labeling that was displaced by excess ghrelin. Interestingly, Cy5-ghrelin, but not the des-acyl analog, showed concentration-dependent binding in mouse heart tissue sections. We then used Cy5-ghrelin to track GHS-R expression in P19-derived cardiomyocytes. Live cell imaging at different time points after DMSO-induced differentiation showed that GHS-R expression preceded that of the differentiation marker aMHC and tracked with the contractility marker SERCA 2a. Our far-red analog of ghrelin adds to the tools we are developing to map GHS-R in developing and diseased cardiac tissues.
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Affiliation(s)
- Gregory A F Douglas
- Departments of Pathology, Chemistry, Medical Imaging, Medical Biophysics, and Oncology, Western University, Richmond Street, London, Ontario, Canada; Imaging Program, Lawson Health Research Institute, 268 Grosvenor Street, London, Ontario N6A 4V2, Canada
| | - Rebecca McGirr
- Departments of Pathology, Chemistry, Medical Imaging, Medical Biophysics, and Oncology, Western University, Richmond Street, London, Ontario, Canada; Imaging Program, Lawson Health Research Institute, 268 Grosvenor Street, London, Ontario N6A 4V2, Canada
| | - Carlie L Charlton
- Departments of Pathology, Chemistry, Medical Imaging, Medical Biophysics, and Oncology, Western University, Richmond Street, London, Ontario, Canada; Imaging Program, Lawson Health Research Institute, 268 Grosvenor Street, London, Ontario N6A 4V2, Canada
| | - Dov B Kagan
- Departments of Pathology, Chemistry, Medical Imaging, Medical Biophysics, and Oncology, Western University, Richmond Street, London, Ontario, Canada; Imaging Program, Lawson Health Research Institute, 268 Grosvenor Street, London, Ontario N6A 4V2, Canada
| | - Lisa M Hoffman
- Departments of Pathology, Chemistry, Medical Imaging, Medical Biophysics, and Oncology, Western University, Richmond Street, London, Ontario, Canada; Imaging Program, Lawson Health Research Institute, 268 Grosvenor Street, London, Ontario N6A 4V2, Canada
| | - Leonard G Luyt
- Departments of Pathology, Chemistry, Medical Imaging, Medical Biophysics, and Oncology, Western University, Richmond Street, London, Ontario, Canada; Imaging Program, Lawson Health Research Institute, 268 Grosvenor Street, London, Ontario N6A 4V2, Canada
| | - Savita Dhanvantari
- Departments of Pathology, Chemistry, Medical Imaging, Medical Biophysics, and Oncology, Western University, Richmond Street, London, Ontario, Canada; Imaging Program, Lawson Health Research Institute, 268 Grosvenor Street, London, Ontario N6A 4V2, Canada.
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Cahill SP, Hatchard T, Abizaid A, Holahan MR. An examination of early neural and cognitive alterations in hippocampal-spatial function of ghrelin receptor-deficient rats. Behav Brain Res 2014; 264:105-15. [PMID: 24525421 DOI: 10.1016/j.bbr.2014.02.004] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2013] [Revised: 01/29/2014] [Accepted: 02/03/2014] [Indexed: 12/31/2022]
Abstract
Ghrelin, a hormone implicated in the regulation of feeding and energy balance, has also been associated with neural function underlying learning and memory. These effects are thought to be mediated by ghrelin targeting receptors at extra hypothalamic sites such as the hippocampus. Exogenous ghrelin administration increases dendritic spine density in the hippocampal CA1 region and neurogenesis in the dentate gyrus (DG), while improving memory in rats. In the present study, we sought to determine whether rats lacking the ghrelin receptor would show early neural or cognitive decline measured via hippocampal integrity (spine density and neurogenesis) and spatial learning and memory. As such, we used young and middle-aged adult rats with mutations to the gene encoding for the ghrelin receptor (GHS-R KO) and wildtype (WT) littermates to determine differences in performance on hippocampal-dependent tasks (the water maze and radial arm maze). In addition, we examined the hippocampal dentate gyrus of these rats for differences in dendritic spine density and cell proliferation (doublecortin). Overall, results demonstrated that spine density and doublecortin staining in the dentate gyrus of the young GHS-R KO group was similar to that seen in middle-aged groups (both KO and WT) and lower than the young WT group. Middle-aged GHS-R KO and WT groups showed deficits on the radial arm maze food-motivated task but not the water maze task. These data suggest that impaired ghrelin signaling leads to an early onset decrement in hippocampal structural integrity that may manifest in non- spatial-related behavioral deficits.
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Affiliation(s)
- Shaina P Cahill
- Department of Neuroscience, Carleton University, Ottawa, ON, Canada
| | - Taylor Hatchard
- Department of Neuroscience, Carleton University, Ottawa, ON, Canada
| | - Alfonso Abizaid
- Department of Neuroscience, Carleton University, Ottawa, ON, Canada
| | - Matthew R Holahan
- Department of Neuroscience, Carleton University, Ottawa, ON, Canada.
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Goebel-Stengel M, Stengel A, Wang L, Taché Y. Orexigenic response to tail pinch: role of brain NPY(1) and corticotropin releasing factor receptors. Am J Physiol Regul Integr Comp Physiol 2014; 306:R164-74. [PMID: 24338440 PMCID: PMC3921301 DOI: 10.1152/ajpregu.00335.2013] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2013] [Accepted: 12/10/2013] [Indexed: 12/30/2022]
Abstract
Tail pinch stimulates food intake in rats. We investigated brain mechanisms of this response and the influence of repeated exposure. Sprague-Dawley rats received acute (5 min) or repeated (5 min/day for 14 days) tail pinch using a padded clip. Acute tail pinch increased 5-min food intake compared with control (0.92 ± 0.2 vs. 0.03 ± 0.01 g, P < 0.01). This response was inhibited by 76% by intracerebroventricular injection of BIBP-3226, a neuropeptide Y1 (NPY1) receptor antagonist, increased by 48% by astressin-B, a corticotropin-releasing factor (CRF) receptor antagonist, and not modified by S-406-028, a somatostatin subtype 2 antagonist. After the 5-min tail pinch without food, blood glucose rose by 21% (P < 0.01) while changes in plasma acyl ghrelin (+41%) and adrenocorticotropic hormone (+37%) were not significant. Two tail pinches (45 min apart) activate pontine and hindbrain catecholaminergic and hypothalamic paraventricular CRF neurons. After 14 days of repeated tail pinch, the 5-min orexigenic response was not significantly different from days 2 to 11 but reduced by 50% thereafter (P < 0.001). Simultaneously, the 5-min fecal pellet output increased during the last 5 days compared with the first 5 days (+58%, P < 0.05). At day 14, the body weight gain was reduced by 22%, with a 99% inhibition of fat gain and a 25% reduction in lean mass (P < 0.05). The orexigenic response to acute 5-min tail pinch is likely to involve the activation of brain NPY1 signaling, whereas that of CRF tends to dampen the acute response and may contribute to increased defecation and decreased body weight gain induced by repeated tail pinch.
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Affiliation(s)
- Miriam Goebel-Stengel
- CURE Digestive Diseases Research Center, Center for Neurobiology of Stress, Digestive Diseases Division, Department of Medicine, at University of California Los Angeles and Veterans Affairs Greater Los Angeles Healthcare System, Los Angeles, California
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Raspopow K, Abizaid A, Matheson K, Anisman H. Anticipation of a psychosocial stressor differentially influences ghrelin, cortisol and food intake among emotional and non-emotional eaters. Appetite 2013; 74:35-43. [PMID: 24295926 DOI: 10.1016/j.appet.2013.11.018] [Citation(s) in RCA: 40] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2013] [Revised: 09/25/2013] [Accepted: 11/26/2013] [Indexed: 12/21/2022]
Abstract
Negative emotions trigger eating in some individuals (emotional eaters) possibly by influencing stress hormones that contribute to eating regulation (e.g., cortisol), or eating-related peptides (e.g., ghrelin) signaling food initiation. The present study assessed whether stressor-elicited cortisol and ghrelin changes would differ between emotional and non-emotional eaters, and whether eating would influence these neuroendocrine responses. Undergraduate women (N=103) who completed measures of emotional eating, were assigned to anticipate either a stressful (public speaking) or non-stressful event. During this period, participants were or were not offered food. Blood samples were taken continuously over a 40-min period to assess changes of cortisol and ghrelin levels, and mood was assessed after the anticipation period. Baseline ghrelin levels were lower in emotional than non-emotional eaters, and this relation was mediated by percent body fat. Ghrelin levels were elevated among women anticipating a stressor, compared to those in the control condition. Additionally, the normal decline of ghrelin following food consumption was not apparent among emotional eaters. Although food intake was not tied to hormone responses, reported hunger was associated with greater food intake for women in the stressor condition. It was suggested that emotional eating coupled with subjective feelings of hunger, might contribute to eating in response to an acute stressor. Additionally, feedback mechanisms controlling the normalization of ghrelin levels might be disturbed in emotional eaters. The similarity of the ghrelin profile of emotional eaters to that of binge eaters and obese individuals, raises the possibility that disturbed ghrelin response might be a risk factor for such conditions.
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Affiliation(s)
- Kate Raspopow
- Department of Neuroscience, LSRB 333, Carleton University, 1125 Colonel By Drive, Ottawa, ON K1S 5B6, Canada.
| | - Alfonso Abizaid
- Department of Neuroscience, LSRB 333, Carleton University, 1125 Colonel By Drive, Ottawa, ON K1S 5B6, Canada.
| | - Kimberly Matheson
- Department of Neuroscience, LSRB 333, Carleton University, 1125 Colonel By Drive, Ottawa, ON K1S 5B6, Canada; Department of Psychology, Carleton University, 1125 Colonel By Drive, Ottawa, ON K1S 5B6, Canada.
| | - Hymie Anisman
- Department of Neuroscience, LSRB 333, Carleton University, 1125 Colonel By Drive, Ottawa, ON K1S 5B6, Canada.
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Wellman PJ, Clifford PS, Rodriguez JA. Ghrelin and ghrelin receptor modulation of psychostimulant action. Front Neurosci 2013; 7:171. [PMID: 24093007 PMCID: PMC3782693 DOI: 10.3389/fnins.2013.00171] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2013] [Accepted: 09/02/2013] [Indexed: 12/03/2022] Open
Abstract
Ghrelin (GHR) is an orexigenic gut peptide that modulates multiple homeostatic functions including gastric emptying, anxiety, stress, memory, feeding, and reinforcement. GHR is known to bind and activate growth-hormone secretagogue receptors (termed GHR-Rs). Of interest to our laboratory has been the assessment of the impact of GHR modulation of the locomotor activation and reward/reinforcement properties of psychostimulants such as cocaine and nicotine. Systemic GHR infusions augment cocaine stimulated locomotion and conditioned place preference (CPP) in rats, as does food restriction (FR) which elevates plasma ghrelin levels. Ghrelin enhancement of psychostimulant function may occur owing to a direct action on mesolimbic dopamine function or may reflect an indirect action of ghrelin on glucocorticoid pathways. Genomic or pharmacological ablation of GHR-Rs attenuates the acute locomotor-enhancing effects of nicotine, cocaine, amphetamine and alcohol and blunts the CPP induced by food, alcohol, amphetamine and cocaine in mice. The stimulant nicotine can induce CPP and like amphetamine and cocaine, repeated administration of nicotine induces locomotor sensitization in rats. Inactivation of ghrelin circuit function in rats by injection of a ghrelin receptor antagonist (e.g., JMV 2959) diminishes the development of nicotine-induced locomotor sensitization. These results suggest a key permissive role for GHR-R activity for the induction of locomotor sensitization to nicotine. Our finding that GHR-R null rats exhibit diminished patterns of responding for intracranial self-stimulation complements an emerging literature implicating central GHR circuits in drug reward/reinforcement. Finally, antagonism of GHR-Rs may represent a smoking cessation modality that not only blocks nicotine-induced reward but that also may limit weight gain after smoking cessation.
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Affiliation(s)
- Paul J Wellman
- Behavioral Neuroscience Program, Department of Psychology, Texas A&M University College Station, TX, USA
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Schellekens H, Dinan TG, Cryan JF. Taking two to tango: a role for ghrelin receptor heterodimerization in stress and reward. Front Neurosci 2013; 7:148. [PMID: 24009547 PMCID: PMC3757321 DOI: 10.3389/fnins.2013.00148] [Citation(s) in RCA: 63] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/28/2013] [Accepted: 08/01/2013] [Indexed: 12/25/2022] Open
Abstract
The gut hormone, ghrelin, is the only known peripherally derived orexigenic signal. It activates its centrally expressed receptor, the growth hormone secretagogue receptor (GHS-R1a), to stimulate food intake. The ghrelin signaling system has recently been suggested to play a key role at the interface of homeostatic control of appetite and the hedonic aspects of food intake, as a critical role for ghrelin in dopaminergic mesolimbic circuits involved in reward signaling has emerged. Moreover, enhanced plasma ghrelin levels are associated with conditions of physiological stress, which may underline the drive to eat calorie-dense "comfort-foods" and signifies a role for ghrelin in stress-induced food reward behaviors. These complex and diverse functionalities of the ghrelinergic system are not yet fully elucidated and likely involve crosstalk with additional signaling systems. Interestingly, accumulating data over the last few years has shown the GHS-R1a receptor to dimerize with several additional G-protein coupled receptors (GPCRs) involved in appetite signaling and reward, including the GHS-R1b receptor, the melanocortin 3 receptor (MC3), dopamine receptors (D1 and D2), and more recently, the serotonin 2C receptor (5-HT2C). GHS-R1a dimerization was shown to affect downstream signaling and receptor trafficking suggesting a potential novel mechanism for fine-tuning GHS-R1a receptor mediated activity. This review summarizes ghrelin's role in food reward and stress and outlines the GHS-R1a dimer pairs identified to date. In addition, the downstream signaling and potential functional consequences of dimerization of the GHS-R1a receptor in appetite and stress-induced food reward behavior are discussed. The existence of multiple GHS-R1a heterodimers has important consequences for future pharmacotherapies as it significantly increases the pharmacological diversity of the GHS-R1a receptor and has the potential to enhance specificity of novel ghrelin-targeted drugs.
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Patterson ZR, Abizaid A. Stress induced obesity: lessons from rodent models of stress. Front Neurosci 2013; 7:130. [PMID: 23898237 PMCID: PMC3721047 DOI: 10.3389/fnins.2013.00130] [Citation(s) in RCA: 68] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2013] [Accepted: 07/08/2013] [Indexed: 11/15/2022] Open
Abstract
Stress was once defined as the non-specific result of the body to any demand or challenge to homeostasis. A more current view of stress is the behavioral and physiological responses generated in the face of, or in anticipation of, a perceived threat. The stress response involves activation of the sympathetic nervous system and recruitment of the hypothalamic-pituitary-adrenal (HPA) axis. When an organism encounters a stressor (social, physical, etc.), these endogenous stress systems are stimulated in order to generate a fight-or-flight response, and manage the stressful situation. As such, an organism is forced to liberate energy resources in attempt to meet the energetic demands posed by the stressor. A change in the energy homeostatic balance is thus required to exploit an appropriate resource and deliver useable energy to the target muscles and tissues involved in the stress response. Acutely, this change in energy homeostasis and the liberation of energy is considered advantageous, as it is required for the survival of the organism. However, when an organism is subjected to a prolonged stressor, as is the case during chronic stress, a continuous irregularity in energy homeostasis is considered detrimental and may lead to the development of metabolic disturbances such as cardiovascular disease, type II diabetes mellitus and obesity. This concept has been studied extensively using animal models, and the neurobiological underpinnings of stress induced metabolic disorders are beginning to surface. However, different animal models of stress continue to produce divergent metabolic phenotypes wherein some animals become anorexic and lose body mass while others increase food intake and body mass and become vulnerable to the development of metabolic disturbances. It remains unclear exactly what factors associated with stress models can be used to predict the metabolic outcome of the organism. This review will explore a variety of rodent stress models and discuss the elements that influence the metabolic outcome in order to further extend our understanding of stress-induced obesity.
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Patterson ZR, Khazall R, Mackay H, Anisman H, Abizaid A. Central ghrelin signaling mediates the metabolic response of C57BL/6 male mice to chronic social defeat stress. Endocrinology 2013; 154:1080-91. [PMID: 23341196 DOI: 10.1210/en.2012-1834] [Citation(s) in RCA: 84] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
Chronic stressors promote metabolic disturbances, including obesity and metabolic syndrome. Ghrelin, a peptide that promotes appetite and the accumulation of adipose tissue, is also secreted in response to stressors to protect the brain and peripheral tissues from the effects of these stressors. Here we demonstrate that elevated ghrelin levels produced by chronic exposure to social stress are associated with increased caloric intake and body weight gain in male C57BL mice. In contrast, stressed mice lacking ghrelin receptors (GHSR KO mice) or C57BL mice receiving chronic intracerebroventricular delivery of the ghrelin receptor antagonist [d-Lys(3)]-GHRP-6 show attenuated weight gain and feeding responses under the same social stress paradigm. Interestingly, stressed GHSR KO mice showed depleted sc and intrascapular brown fat depots, whereas stressed young wild-type mice did not. In old wild-type mice, chronic social defeat increased visceral and intrascapular brown fat depots in association with increases in obesity markers like hyperleptinemia and hyperinsulinemia along with increased hypothalamic expression of neuropeptide Y and Agouti related peptide. Importantly, the elevated expression of these peptides persisted least for 2 weeks after cessation of the stressor regimen. In contrast, old GHSR KO mice did not show these alterations after chronic social defeat. These results suggest that ghrelin plays an important role in the metabolic adaptations necessary to meet the energetic demands posed by stressors, but chronic exposure to stress-induced ghrelin elevations ultimately could lead to long lasting metabolic dysfunctions.
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MESH Headings
- Adipose Tissue, Brown/pathology
- Aging/pathology
- Aging/physiology
- Aging/psychology
- Animals
- Behavior, Animal/physiology
- Energy Intake/physiology
- Ghrelin/antagonists & inhibitors
- Ghrelin/blood
- Ghrelin/physiology
- Male
- Mice
- Mice, Inbred C57BL
- Mice, Knockout
- Models, Biological
- Obesity/pathology
- Obesity/physiopathology
- Obesity/psychology
- Receptors, Ghrelin/deficiency
- Receptors, Ghrelin/genetics
- Receptors, Ghrelin/physiology
- Signal Transduction/physiology
- Social Behavior
- Stress, Physiological
- Stress, Psychological
- Weight Gain/physiology
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Affiliation(s)
- Z R Patterson
- Department of Neuroscience, Carleton University, 1125 Colonel By Drive, Ottawa, Ontario, K1S 5B6, Canada
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Willey AR, Spear LP. Effects of acute ethanol administration and chronic stress exposure on social investigation and 50kHz ultrasonic vocalizations in adolescent and adult male Sprague-Dawley rats. Pharmacol Biochem Behav 2013; 105:17-25. [PMID: 23360955 DOI: 10.1016/j.pbb.2013.01.012] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/14/2012] [Revised: 01/16/2013] [Accepted: 01/19/2013] [Indexed: 02/04/2023]
Abstract
Adolescents drink largely in social situations, likely in an attempt to facilitate social interactions. This study sought to examine alterations in the incentive salience of a social stimulus following repeated stress exposure and acute ethanol administration in adolescent and adult male Sprague-Dawley rats. Subjects were either exposed to 5days of restraint stress, chronic variable stress (CVS), which consisted of a different stressor every day, or non-stressed. On test day, the animals were injected with 0, 0.25, 0.5, or 0.75g/kg ethanol and placed in a social approach test in which they could see, hear, and smell a social conspecific, but could not physically interact with it. All the animals showed an interest in the social stimulus, with adolescents engaging in more social investigation than adults. Restraint stressed adults showed ethanol-induced increases in social investigation, while ethanol effects were not seen in any other group. An ethanol-associated increase in 50kHz ultrasonic vocalization (USV) production was only evident in restraint stressed adolescents following 0.75g/kg ethanol. 50kHz USVs were not correlated with time spent investigating the social stimulus in any test condition. These results show that age differences in the facilitatory effects of ethanol on incentive salience of social stimuli are moderated by stress, with the facilitation of social approach by ethanol only evident in restraint stressed adults.
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Affiliation(s)
- Amanda R Willey
- Department of Psychology, Center for Development and Behavioral Neuroscience, Binghamton University (SUNY), PO Box 6000, Binghamton, NY 13902, USA.
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45
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Kumar J, Chuang JC, Na ES, Kuperman A, Gillman AG, Mukherjee S, Zigman JM, McClung CA, Lutter M. Differential effects of chronic social stress and fluoxetine on meal patterns in mice. Appetite 2013; 64:81-8. [PMID: 23318656 DOI: 10.1016/j.appet.2012.12.023] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2012] [Revised: 11/09/2012] [Accepted: 12/14/2012] [Indexed: 01/03/2023]
Abstract
Both chronic stress and antidepressant medications have been associated with changes in body weight. In the current study, we investigate mechanisms by which stress and antidepressants interact to affect meal patterns. A group of mice was subjected to the chronic social defeat stress model of major depression followed by fluoxetine treatment and was subsequently analyzed for food intake using metabolic cages. We report that chronic social defeat stress increases food intake by specifically increasing meal size, an effect that is reversed by fluoxetine treatment. In an attempt to gain mechanistic insight into changes in meal patterning induced by stress and fluoxetine, fasting serum samples were collected every 4h over a 24-h period, and acyl-ghrelin, leptin, and corticosterone levels were measured. Chronic stress induces a peak in acyl-ghrelin levels just prior to the onset of the dark phase, which is shifted in mice treated with fluoxetine. Taken together, these results indicate that stress increases food intake by decreasing satiation, and that fluoxetine can reverse stress-induced changes in meal patterns.
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Affiliation(s)
- Jaswinder Kumar
- Department of Psychiatry, University of Texas Southwestern Medical Center, 5323 Harry Hines Boulevard, Dallas, TX 75390-9070, USA.
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46
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Abstract
Research into the control of energy balance has tended to focus on discrete brain regions, such as the brainstem, medulla, arcuate nucleus of the hypothalamus, and neocortex. Recently, a larger picture has begun to emerge in which the coordinated communication between these areas is proving to be critical to appropriate regulation of metabolism. By serving as a center for such communication, the paraventricular nucleus of the hypothalamus (PVH) is perhaps the most important brain nucleus regulating the physiological response to energetic challenges. Here we review recent advances in the understanding of the circuitry and function of the PVH.
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Affiliation(s)
- Jennifer W. Hill
- Department of Physiology and Pharmacology, Center for Diabetes and Endocrine Research, University of Toledo Medical Center, Obstetrics-Gynecology, University of Toledo, USA
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47
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Kirsz K, Zieba DA. A review on the effect of the photoperiod and melatonin on interactions between ghrelin and serotonin. Gen Comp Endocrinol 2012; 179:248-53. [PMID: 22974511 DOI: 10.1016/j.ygcen.2012.08.025] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/14/2012] [Revised: 07/07/2012] [Accepted: 08/23/2012] [Indexed: 12/21/2022]
Abstract
Ghrelin and serotonin, which exhibit rhythmic secretion profiles under feeding/fasting conditions, are sensitive to increases and decreases in the day length and form a close web of interrelationships in the regulation of energy homeostasis. Ghrelin and serotonin are biochemically and functionally linked to the suprachiasmatic nucleus, which is a circadian pacemaker, and melatonin, which is an internal transducer of photic environmental changes. Ghrelin and serotonin might be candidates for integrating photic and nonphotic signals, such as light and food availability in the central nervous system. The mechanisms that convert a light signal into a variety of physiological and behavioral rhythms remain unknown. However, we know that the conversion of light signals is necessary to maximize an animal's chances of survival and reproduction.
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Affiliation(s)
- Katarzyna Kirsz
- Department of Swine and Small Ruminant Breeding, Laboratory of Genomics and Biotechnology, University of Agriculture, Krakow 30-059, Poland
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48
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Hill MN, Hellemans KGC, Verma P, Gorzalka BB, Weinberg J. Neurobiology of chronic mild stress: parallels to major depression. Neurosci Biobehav Rev 2012; 36:2085-117. [PMID: 22776763 PMCID: PMC4821201 DOI: 10.1016/j.neubiorev.2012.07.001] [Citation(s) in RCA: 304] [Impact Index Per Article: 25.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2011] [Revised: 06/21/2012] [Accepted: 07/01/2012] [Indexed: 01/28/2023]
Abstract
The chronic mild (or unpredictable/variable) stress (CMS) model was developed as an animal model of depression more than 20 years ago. The foundation of this model was that following long-term exposure to a series of mild, but unpredictable stressors, animals would develop a state of impaired reward salience that was akin to the anhedonia observed in major depressive disorder. In the time since its inception, this model has also been used for a variety of studies examining neurobiological variables that are associated with depression, despite the fact that this model has never been critically examined to validate that the neurobiological changes induced by CMS are parallel to those documented in depressive disorder. The aim of the current review is to summarize the current state of knowledge regarding the effects of chronic mild stress on neurobiological variables, such as neurochemistry, neurochemical receptor expression and functionality, neurotrophin expression and cellular plasticity. These findings are then compared to those of clinical research examining common variables in populations with depressive disorders to determine if the changes observed following chronic mild stress are in fact consistent with those observed in major depression. We conclude that the chronic mild stress paradigm: (1) evokes an array of neurobiological changes that mirror those seen in depressive disorders and (2) may be a suitable tool to investigate novel systems that could be disturbed in depression, and thus aid in the development of novel targets for the treatment of depression.
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Affiliation(s)
- Matthew N Hill
- Departments of Cell Biology and Anatomy, Hotchkiss Brain Institute, University of Calgary, Calgary, AB Canada.
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Perelló M, Zigman JM. The role of ghrelin in reward-based eating. Biol Psychiatry 2012; 72:347-53. [PMID: 22458951 PMCID: PMC3388148 DOI: 10.1016/j.biopsych.2012.02.016] [Citation(s) in RCA: 98] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/21/2011] [Revised: 02/03/2012] [Accepted: 02/17/2012] [Indexed: 01/18/2023]
Abstract
The peptide hormone ghrelin acts in the central nervous system as a potent orexigenic signal. Not only is ghrelin recognized as playing an important role in feeding circuits traditionally thought of as affecting body weight homeostasis, but also an accumulating number of scientific studies have identified ghrelin as being a key regulator of reward-based, hedonic eating behaviors. In the current article, we review ghrelin's orexigenic actions, the evidence linking ghrelin to food reward behavior, potential mechanisms by which ghrelin mediates reward-based eating behavior, and those studies suggesting an obligatory role for ghrelin in the changed eating behaviors induced by stress.
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Affiliation(s)
- Mario Perelló
- Laboratory of Neurophysiology, Multidisciplinary Institute of Cell Biology (IMBICE-CONICET/CICPBA), Calle 526 s/n entre 10 y 11, La Plata, Buenos Aires, Argentina 1900
| | - Jeffrey M. Zigman
- Department of Internal Medicine (Divisions of Hypothalamic Research and of Endocrinology & Metabolism), The University of Texas Southwestern Medical Center, 5323 Harry Hines Blvd., Dallas, Texas 75390-9077,Department of Psychiatry, The University of Texas Southwestern Medical Center, 5323 Harry Hines Blvd., Dallas, Texas 75390-9077
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Schellekens H, Finger BC, Dinan TG, Cryan JF. Ghrelin signalling and obesity: at the interface of stress, mood and food reward. Pharmacol Ther 2012; 135:316-26. [PMID: 22749794 DOI: 10.1016/j.pharmthera.2012.06.004] [Citation(s) in RCA: 147] [Impact Index Per Article: 12.3] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2012] [Accepted: 06/07/2012] [Indexed: 12/14/2022]
Abstract
The neuronal circuitry underlying the complex relationship between stress, mood and food intake are slowly being unravelled and several studies suggest a key role herein for the peripherally derived hormone, ghrelin. Evidence is accumulating linking obesity as an environmental risk factor to psychiatric disorders such as stress, anxiety and depression. Ghrelin is the only known orexigenic hormone from the periphery to stimulate food intake. Plasma ghrelin levels are enhanced under conditions of physiological stress and ghrelin has recently been suggested to play an important role in stress-induced food reward behaviour. In addition, chronic stress or atypical depression has often demonstrated to correlate with an increase in ingestion of caloric dense 'comfort foods' and have been implicated as one of the major contributor to the increased prevalence of obesity. Recent evidence suggests ghrelin as a critical factor at the interface of homeostatic control of appetite and reward circuitries, modulating the hedonic aspects of food intake. Therefore, the reward-related feeding of ghrelin may reveal itself as an important factor in the development of addiction to certain foods, similar to its involvement in the dependence to drugs of abuse, including alcohol. This review will highlight the accumulating evidence demonstrating the close interaction between food, mood and stress and the development of obesity. We consider the ghrelinergic system as an effective target for the development of successful anti-obesity pharmacotherapies, which not only affects appetite but also selectively modulates the rewarding properties of food and impact on psychological well-being in conditions of stress, anxiety and depression.
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