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Moran KM, Delville Y. A hamster model for stress-induced weight gain. Horm Behav 2024; 160:105488. [PMID: 38306877 DOI: 10.1016/j.yhbeh.2024.105488] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/05/2023] [Revised: 12/18/2023] [Accepted: 01/18/2024] [Indexed: 02/04/2024]
Abstract
This review addresses the translational relevance of animal models of stress and their effects on body weight. In humans, stress, whether chronic or acute, has often been associated with increased food intake and weight gain. In view of the current obesity epidemic, this phenomenon is especially relevant. Such observations contrast with reports with commonly used laboratory animals, especially rats and mice. In these species, it is common to find individuals gaining less weight under stress, even with potent social stressors. However, there are laboratory species that present increased appetite and weight gain under stress, such as golden hamsters. Furthermore, these animals also include metabolic and behavioral similarities with humans, including hoarding behavior which is also enhanced under stress. Consequently, we propose that our comparative perspective provides useful insights for future research on the development of obesity in humans as a consequence of chronic stress exposure.
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Affiliation(s)
- Kevin M Moran
- Psychology Department, The University of Texas at Austin, USA.
| | - Yvon Delville
- Psychology Department, The University of Texas at Austin, USA
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2
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MacCormack JK, Muscatell KA. The metabolic mind: A role for leptin and ghrelin in affect and social cognition. SOCIAL AND PERSONALITY PSYCHOLOGY COMPASS 2019. [DOI: 10.1111/spc3.12496] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
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3
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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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4
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Effect of astressin, a corticoliberin antagonist, on aggression and anxiety-fobic states in male rats reared in social isolation. ACTA ACUST UNITED AC 2017. [DOI: 10.17816/rcf15338-47] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Aim. Intraspecific behavior, emotional and explorative activity were investigated after intranasal administration of astressin, a non-selective antagonist of CRF receptors, in the male rats reared in social isolation from 21 to 93 days.
Results. In the “resident-intruder” test there was an increased level of aggression and communications in isolated rats compared to grouped animals. After intranasal administration of astressin (20 μg in 20 μl), rats grown in isolation demonstrated an increase in aggression and decreased in communicability compared to intact animals reared in isolation. In the “open field” test a level of motor activity was increased in rats grown in isolation compared to grouped animals. The anxiety-phobic state, as well as behavior in an elevated plus maze, revealed enhance of anxiety and fear in rats reared in isolation. After astressin administration to isolated animals the levels of anxiety and fear significantly decreased.
Conclusion. The results of the work revealed that the antagonist of the CRF receptor astressin disinhibited aggression, removing anxious and phobic state in male rats reared in social isolation. The results prove the necessity of taking into account CRF mechanisms in the formation of the social isolation syndrome and the possibility of using CRF receptor antagonists to control the central mechanisms of stress and dependence in ontogenesis.
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Talukdar S, Zhou Y, Li D, Rossulek M, Dong J, Somayaji V, Weng Y, Clark R, Lanba A, Owen BM, Brenner MB, Trimmer JK, Gropp KE, Chabot JR, Erion DM, Rolph TP, Goodwin B, Calle RA. A Long-Acting FGF21 Molecule, PF-05231023, Decreases Body Weight and Improves Lipid Profile in Non-human Primates and Type 2 Diabetic Subjects. Cell Metab 2016; 23:427-40. [PMID: 26959184 DOI: 10.1016/j.cmet.2016.02.001] [Citation(s) in RCA: 364] [Impact Index Per Article: 45.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/15/2015] [Revised: 07/08/2015] [Accepted: 02/03/2016] [Indexed: 01/09/2023]
Abstract
FGF21 plays a central role in energy, lipid, and glucose homeostasis. To characterize the pharmacologic effects of FGF21, we administered a long-acting FGF21 analog, PF-05231023, to obese cynomolgus monkeys. PF-05231023 caused a marked decrease in food intake that led to reduced body weight. To assess the effects of PF-05231023 in humans, we conducted a placebo-controlled, multiple ascending-dose study in overweight/obese subjects with type 2 diabetes. PF-05231023 treatment resulted in a significant decrease in body weight, improved plasma lipoprotein profile, and increased adiponectin levels. Importantly, there were no significant effects of PF-05231023 on glycemic control. PF-05231023 treatment led to dose-dependent changes in multiple markers of bone formation and resorption and elevated insulin-like growth factor 1. The favorable effects of PF-05231023 on body weight support further evaluation of this molecule for the treatment of obesity. Longer studies are needed to assess potential direct effects of FGF21 on bone in humans.
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Affiliation(s)
- Saswata Talukdar
- Cardiovascular Metabolic and Endocrine Disease Research Unit, Pfizer Worldwide Research and Development, 610 Main Street, Cambridge, MA 02139, USA.
| | - Yingjiang Zhou
- Cardiovascular Metabolic and Endocrine Disease Research Unit, Pfizer Worldwide Research and Development, 610 Main Street, Cambridge, MA 02139, USA
| | - Dongmei Li
- Cardiovascular Metabolic and Endocrine Disease Research Unit, Pfizer Worldwide Research and Development, 610 Main Street, Cambridge, MA 02139, USA
| | - Michelle Rossulek
- Cardiovascular Metabolic and Endocrine Disease Research Unit, Pfizer Worldwide Research and Development, 610 Main Street, Cambridge, MA 02139, USA
| | - Jennifer Dong
- Cardiovascular Metabolic and Endocrine Disease Research Unit, Pfizer Worldwide Research and Development, 610 Main Street, Cambridge, MA 02139, USA
| | - Veena Somayaji
- Cardiovascular Metabolic and Endocrine Disease Research Unit, Pfizer Worldwide Research and Development, 610 Main Street, Cambridge, MA 02139, USA
| | - Yan Weng
- Pharmacokinetics, Dynamics, and Metabolism, Pfizer Worldwide Research and Development, 610 Main Street, Cambridge, MA 02139, USA
| | - Ronald Clark
- Cardiovascular Metabolic and Endocrine Disease Research Unit, Pfizer Worldwide Research and Development, 610 Main Street, Cambridge, MA 02139, USA
| | - Adhiraj Lanba
- Cardiovascular Metabolic and Endocrine Disease Research Unit, Pfizer Worldwide Research and Development, 610 Main Street, Cambridge, MA 02139, USA
| | - Bryn M Owen
- Department of Pharmacology, University of Texas Southwestern Medical Center, Dallas, TX 75390, USA
| | - Martin B Brenner
- Cardiovascular Metabolic and Endocrine Disease Research Unit, Pfizer Worldwide Research and Development, 610 Main Street, Cambridge, MA 02139, USA
| | - Jeffrey K Trimmer
- Cardiovascular Metabolic and Endocrine Disease Research Unit, Pfizer Worldwide Research and Development, 610 Main Street, Cambridge, MA 02139, USA
| | - Kathryn E Gropp
- Drug Safety Research and Development, Pfizer Inc., Groton, CT 06340, USA
| | - Jeffrey R Chabot
- Pharmacokinetics, Dynamics, and Metabolism, Pfizer Worldwide Research and Development, 610 Main Street, Cambridge, MA 02139, USA
| | - Derek M Erion
- Cardiovascular Metabolic and Endocrine Disease Research Unit, Pfizer Worldwide Research and Development, 610 Main Street, Cambridge, MA 02139, USA
| | - Timothy P Rolph
- Cardiovascular Metabolic and Endocrine Disease Research Unit, Pfizer Worldwide Research and Development, 610 Main Street, Cambridge, MA 02139, USA
| | - Bryan Goodwin
- Cardiovascular Metabolic and Endocrine Disease Research Unit, Pfizer Worldwide Research and Development, 610 Main Street, Cambridge, MA 02139, USA
| | - Roberto A Calle
- Cardiovascular Metabolic and Endocrine Disease Research Unit, Pfizer Worldwide Research and Development, 610 Main Street, Cambridge, MA 02139, USA.
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6
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Harris RBS. Chronic and acute effects of stress on energy balance: are there appropriate animal models? Am J Physiol Regul Integr Comp Physiol 2015; 308:R250-65. [PMID: 25519732 PMCID: PMC4329465 DOI: 10.1152/ajpregu.00361.2014] [Citation(s) in RCA: 84] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2014] [Accepted: 12/12/2014] [Indexed: 11/22/2022]
Abstract
Stress activates multiple neural and endocrine systems to allow an animal to respond to and survive in a threatening environment. The corticotropin-releasing factor system is a primary initiator of this integrated response, which includes activation of the sympathetic nervous system and the hypothalamic-pituitary-adrenal (HPA) axis. The energetic response to acute stress is determined by the nature and severity of the stressor, but a typical response to an acute stressor is inhibition of food intake, increased heat production, and increased activity with sustained changes in body weight, behavior, and HPA reactivity. The effect of chronic psychological stress is more variable. In humans, chronic stress may cause weight gain in restrained eaters who show increased HPA reactivity to acute stress. This phenotype is difficult to replicate in rodent models where chronic psychological stress is more likely to cause weight loss than weight gain. An exception may be hamsters subjected to repeated bouts of social defeat or foot shock, but the data are limited. Recent reports on the food intake and body composition of subordinate members of group-housed female monkeys indicate that these animals have a similar phenotype to human stress-induced eaters, but there are a limited number of investigators with access to the model. Few stress experiments focus on energy balance, but more information on the phenotype of both humans and animal models during and after exposure to acute or chronic stress may provide novel insight into mechanisms that normally control body weight.
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Affiliation(s)
- Ruth B S Harris
- Department of Physiology, Medical College of Georgia, Georgia Regents University, Augusta, Georgia
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7
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Abstract
This manuscript summarizes the proceedings of the symposium entitled, "Stress, Palatable Food and Reward", that was chaired by Drs. Linda Rinaman and Yvonne Ulrich-Lai at the 2014 Neurobiology of Stress Workshop held in Cincinnati, OH. This symposium comprised research presentations by four neuroscientists whose work focuses on the biological bases for complex interactions among stress, food intake and emotion. First, Dr Ulrich-Lai describes her rodent research exploring mechanisms by which the rewarding properties of sweet palatable foods confer stress relief. Second, Dr Stephanie Fulton discusses her work in which excessive, long-term intake of dietary lipids, as well as their subsequent withdrawal, promotes stress-related outcomes in mice. Third, Dr Mark Wilson describes his group's research examining the effects of social hierarchy-related stress on food intake and diet choice in group-housed female rhesus macaques, and compared the data from monkeys to results obtained in analogous work using rodents. Finally, Dr Gorica Petrovich discusses her research program that is aimed at defining cortical-amygdalar-hypothalamic circuitry responsible for curbing food intake during emotional threat (i.e. fear anticipation) in rats. Their collective results reveal the complexity of physiological and behavioral interactions that link stress, food intake and emotional state, and suggest new avenues of research to probe the impact of genetic, metabolic, social, experiential and environmental factors on these interactions.
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Affiliation(s)
- Yvonne M. Ulrich-Lai
- Dept. of Psychiatry and Behavioral Neuroscience, University of Cincinnati, Cincinnati, OH 45219
| | - Stephanie Fulton
- CRCHUM, Dept. of Nutrition, Université de Montréal, Montreal, QC, Canada, H1W 4A4
| | - Mark Wilson
- Division of Developmental and Cognitive Neuroscience, Emory, Yerkes National Primate Research Center, Emory University, Atlanta, GA 30322
| | | | - Linda Rinaman
- Dept. of Neuroscience, University of Pittsburgh, Pittsburgh, PA 15260
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8
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Wilson ME, Moore CJ, Ethun KF, Johnson ZP. Understanding the control of ingestive behavior in primates. Horm Behav 2014; 66:86-94. [PMID: 24727080 PMCID: PMC4051844 DOI: 10.1016/j.yhbeh.2014.04.005] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/01/2013] [Revised: 04/01/2014] [Accepted: 04/05/2014] [Indexed: 01/08/2023]
Abstract
This article is part of a Special Issue "Energy Balance". Ingestive behavior in free-ranging populations of nonhuman primates is influenced by resource availability and social group organization and provides valuable insight on the evolution of ecologically adaptive behaviors and physiological systems. As captive populations were established, questions regarding proximate mechanisms that regulate food intake in these animals could be more easily addressed. The availability of these captive populations has led to the use of selected species to understand appetite control or metabolic physiology in humans. Recognizing the difficulty of quantitating food intake in free-ranging groups, the use of captive, singly-housed animals provided a distinct advantage though, at the same time, produced a different social ecology from the animals' natural habitat. However, the recent application of novel technologies to quantitate caloric intake and energy expenditure in free-feeding, socially housed monkeys permits prospective studies that can accurately define how food intake changes in response to any number of interventions in the context of a social environment. This review provides an overview of studies examining food intake using captive nonhuman primates organized into three areas: a) neurochemical regulation of food intake in nonhuman primates; b) whether exposure to specific diets during key developmental periods programs differences in diet preferences or changes the expression of feeding related neuropeptides; and c) how psychosocial factors influence appetite regulation. Because feeding patterns are driven by more than just satiety and orexigenic signals, appreciating how the social context influences pattern of feeding in nonhuman primates may be quite informative for understanding the biological complexity of feeding in humans.
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Affiliation(s)
- Mark E Wilson
- Division of Developmental & Cognitive Neuroscience, Yerkes National Primate Research Center, Emory University, Atlanta, GA 30322, USA.
| | - Carla J Moore
- Division of Developmental & Cognitive Neuroscience, Yerkes National Primate Research Center, Emory University, Atlanta, GA 30322, USA; Graduate Program in Nutrition & Health Sciences, Emory University, Atlanta, GA 30322, USA
| | - Kelly F Ethun
- Division of Animal Resources, Yerkes National Primate Research Center, Emory University, Atlanta, GA 30322, USA
| | - Zachary P Johnson
- Division of Developmental & Cognitive Neuroscience, Yerkes National Primate Research Center, Emory University, Atlanta, GA 30322, USA
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Michopoulos V, Embree M, Reding K, Sanchez MM, Toufexis D, Votaw JR, Voll RJ, Goodman MM, Rivier J, Wilson ME, Berga SL. CRH receptor antagonism reverses the effect of social subordination upon central GABAA receptor binding in estradiol-treated ovariectomized female rhesus monkeys. Neuroscience 2013; 250:300-8. [PMID: 23856065 DOI: 10.1016/j.neuroscience.2013.07.002] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2013] [Revised: 06/28/2013] [Accepted: 07/01/2013] [Indexed: 01/22/2023]
Abstract
Persistent exposure to environmental stressors causes dysregulation of the limbic-hypothalamic-pituitary-adrenal (LHPA) axis and alters GABAA receptor (GABAAR) levels throughout the brain. Social subordination in socially housed female rhesus results in distinctive stress-related physiological and behavioral phenotypes that are dependent on the ovarian hormone estradiol (E2). In the present study, we utilized ovariectomized adult female rhesus monkeys undergoing hormone replacement with E2 to test the hypothesis that the chronic psychosocial stress of subordination alters GABAAR binding potential (GABAAR BPND) in limbic regions implicated in emotional processing including the prefrontal cortex, temporal lobe (amygdala and hippocampus), and hypothalamus. Furthermore, we tested the hypothesis that peripheral administration of a corticotropin-releasing hormone (CRH) receptor antagonist (astressin B) would reverse the alterations in GABAAR binding within these regions in subordinate females. After subjects received astressin B or saline for three consecutive days, GABAAR BPND was determined by positron emission tomography (PET) using (18)F-flumazenil as a radioligand. T1-weighted structural magnetic resonance imaging scans were also acquired for PET scan co-registration, in order to perform a region of interest analysis using the pons as a reference region. Compared to socially dominant females, subordinate females exhibited increased GABAAR BPND in the prefrontal cortex but not in the temporal lobe or the hypothalamus. Administration of astressin B eliminated the status difference in GABAAR BPND in the prefrontal cortex, suggesting that the chronic stressor of social subordination modulates GABAergic tone via effects on CRH and the LHPA axis, at least in prefrontal regions.
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Affiliation(s)
- V Michopoulos
- Department of Psychiatry & Behavioral Sciences, School of Medicine, Emory University, Atlanta, GA, United States; Division of Developmental & Cognitive Neuroscience, Yerkes National Primate Research Center, Emory University, Atlanta, GA, USA.
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10
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Michopoulos V, Reding KM, Wilson ME, Toufexis D. Social subordination impairs hypothalamic-pituitary-adrenal function in female rhesus monkeys. Horm Behav 2012; 62:389-99. [PMID: 22940527 PMCID: PMC3477274 DOI: 10.1016/j.yhbeh.2012.07.014] [Citation(s) in RCA: 56] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/25/2011] [Revised: 07/03/2012] [Accepted: 07/09/2012] [Indexed: 12/29/2022]
Abstract
Linear dominance hierarchies organize and maintain stability in female rhesus macaque (Macaca mulatta) social groups regardless of group size. As a consequence of their low social status, subordinate females suffer from an array of adverse outcomes including reproductive compromise, impaired immune function, and poor cardiovascular health. However, data that differentiate limbic-hypothalamic-pituitary-adrenal axis (LHPA) parameters between dominant from subordinate female monkeys are inconsistent, bringing into question whether social subordination alters the LHPA axis in female macaques. One difficulty in examining LHPA function in macaques may be the confounding effects of cycling ovarian steroids that are known to modulate LHPA activity. The current study used ovariectomized dominant and subordinate female rhesus monkeys to examine the effect that social subordination has on LHPA function by measuring morning and diurnal serum cortisol levels, dexamethasone (Dex) suppression of cortisol, metabolic clearance of Dex, and ACTH stimulation of adrenal cortisol release and cortisol response following exposure to acute social isolation. Compared to dominant females, subordinate females showed diminished morning peak cortisol secretion, weakened glucocorticoid negative feedback, and decreased adrenal cortisol response to an ACTH challenge as well as a restrained cortisol response following social isolation. However, the metabolism of Dex did not account for differences in Dex suppression between dominant and subordinate females. These results indicate that the ability to mount and limit glucocorticoid release is significantly reduced by psychosocial stress in female rhesus macaques, suggesting a hyporesponsive LHPA phenotype which resembles that observed in several human psychopathologies.
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Affiliation(s)
- Vasiliki Michopoulos
- Division of Developmental & Cognitive Neuroscience, Yerkes National Primate Research Center, Emory University, Atlanta GA 30329, USA.
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Michopoulos V, Checchi M, Sharpe D, Wilson ME. Estradiol effects on behavior and serum oxytocin are modified by social status and polymorphisms in the serotonin transporter gene in female rhesus monkeys. Horm Behav 2011; 59:528-35. [PMID: 21316367 PMCID: PMC3081406 DOI: 10.1016/j.yhbeh.2011.02.002] [Citation(s) in RCA: 47] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/24/2010] [Revised: 01/31/2011] [Accepted: 02/02/2011] [Indexed: 12/17/2022]
Abstract
Despite the well-documented relation between estradiol (E2) and behavior, exposure to stressors may modify sensitivity to E2. The effects of E2 on behavior are, in part, likely related to their modulation of the serotonin (5HT) and oxytocin systems. The short allele (s-variant) polymorphism found in the promoter region of the SLC6A4 gene that encodes the 5HT transporter (5HTT) modulates responsivity to stressors. The current study used ovariectomized adult female rhesus monkeys to evaluate how exposure to the psychosocial stressor of social subordination and polymorphisms in the gene encoding 5HTT influence the behavioral effects of E2 and immunoreactive serum oxytocin. Dominant females had higher levels of oxytocin than subordinate animals even though E2 increased immunoreactive serum oxytocin in all females. E2 increased affiliative behaviors in all animals, with even more of these prosocial behaviors directed at dominant females. S-variant females, regardless of social status, were more aggressive toward more subordinate cage mates and these behaviors too were increased by E2. Subordinate s-variant females are most often involved in agonistic behavior, less affiliative behavior, and were less responsive to the anxiolytic action of E2. The results show that the short allele of the 5HTT gene synergizes with psychosocial stress exposure to affect the behavioral efficacy of E2 while confirming the actions of E2 for producing generalized behavioral arousal in females. Whether differences in the central action of 5HT and/or oxytocin are responsible for this effect requires further study.
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Affiliation(s)
- Vasiliki Michopoulos
- Division of Developmental & Cognitive Neuroscience, Yerkes National Primate Research Center, Emory University, Atlanta, GA 30322, USA.
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