1
|
Méquinion M, Foldi CJ, Andrews ZB. The Ghrelin-AgRP Neuron Nexus in Anorexia Nervosa: Implications for Metabolic and Behavioral Adaptations. Front Nutr 2020; 6:190. [PMID: 31998738 PMCID: PMC6962137 DOI: 10.3389/fnut.2019.00190] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2019] [Accepted: 12/11/2019] [Indexed: 11/13/2022] Open
Abstract
Anorexia Nervosa (AN) is viewed as primarily a psychiatric disorder owing to the considerable behavioral and genetic overlap with mood disorders and other psychiatric traits. However, the recent reconceptualization of AN as one of both psychiatric and metabolic etiology suggests that metabolic circuits conveying hunger, or sensitive to signals of hunger, may be a critical nexus linking metabolic dysfunction to mood disturbances. Within the brain, hunger is primarily percieved by Agouti-related (AgRP) neurons and hunger increases plasma concentrations of the hormone ghrelin, which targets ghrelin receptors on AgRP neurons to facilitate metabolic adaptations to low energy availability. However, beyond the fundamental role in maintaining hunger signaling, AgRP neurons regulate a diverse range of behaviors such as motivation, locomotor activity, negative reinforcement, anxiety, and obsession and a key factor involved in the manifestation of these behavioral changes in response to activation is the presence or absence of food availability. These changes can be considered adaptive in that they promote affective food-seeking strategies in environments with limited food availability. However, it also suggests that these neurons, so well-studied for their metabolic control, shape mood-related behaviors in a context-dependent manner and dysfunctional control leads not only to metabolic problems but also potentially mood-related problems. The purpose of this review is to underline the potential role of AgRP neurons and ghrelin signaling in both the metabolic and behavioral changes observed in anorexia nervosa. We aim to highlight the most recent studies on AgRP neurons and ghrelin signaling and integrate their metabolic and behavioral roles in normal function and highlight how dysfunction may contribute to the development of AN.
Collapse
Affiliation(s)
| | | | - Zane B. Andrews
- Monash Biomedicine Discovery Institute and Department of Physiology, Monash University, Clayton, VIC, Australia
| |
Collapse
|
2
|
Yilmaz Z, Kaplan AS, Tiwari AK, Levitan RD, Piran S, Bergen AW, Kaye WH, Hakonarson H, Wang K, Berrettini WH, Brandt HA, Bulik CM, Crawford S, Crow S, Fichter MM, Halmi KA, Johnson CL, Keel PK, Klump KL, Magistretti P, Mitchell JE, Strober M, Thornton LM, Treasure J, Woodside DB, Knight J, Kennedy JL. The role of leptin, melanocortin, and neurotrophin system genes on body weight in anorexia nervosa and bulimia nervosa. J Psychiatr Res 2014; 55:77-86. [PMID: 24831852 PMCID: PMC4191922 DOI: 10.1016/j.jpsychires.2014.04.005] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/08/2014] [Revised: 03/05/2014] [Accepted: 04/04/2014] [Indexed: 12/26/2022]
Abstract
OBJECTIVE Although low weight is a key factor contributing to the high mortality in anorexia nervosa (AN), it is unclear how AN patients sustain low weight compared with bulimia nervosa (BN) patients with similar psychopathology. Studies of genes involved in appetite and weight regulation in eating disorders have yielded variable findings, in part due to small sample size and clinical heterogeneity. This study: (1) assessed the role of leptin, melanocortin, and neurotrophin genetic variants in conferring risk for AN and BN; and (2) explored the involvement of these genes in body mass index (BMI) variations within AN and BN. METHOD Our sample consisted of 745 individuals with AN without a history of BN, 245 individuals with BN without a history of AN, and 321 controls. We genotyped 20 markers with known or putative function among genes selected from leptin, melanocortin, and neurotrophin systems. RESULTS There were no significant differences in allele frequencies among individuals with AN, BN, and controls. AGRP rs13338499 polymorphism was associated with lowest illness-related BMI in those with AN (p = 0.0013), and NTRK2 rs1042571 was associated with highest BMI in those with BN (p = 0.0018). DISCUSSION To our knowledge, this is the first study to address the issue of clinical heterogeneity in eating disorder genetic research and to explore the role of known or putatively functional markers in genes regulating appetite and weight in individuals with AN and BN. If replicated, our results may serve as an important first step toward gaining a better understanding of weight regulation in eating disorders.
Collapse
Affiliation(s)
- Zeynep Yilmaz
- Department of Psychiatry, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA; Clinical Research Department, Centre for Addiction and Mental Health, Toronto, Canada
| | - Allan S Kaplan
- Clinical Research Department, Centre for Addiction and Mental Health, Toronto, Canada; Institute of Medical Science, University of Toronto, Toronto, Canada; Department of Psychiatry, University of Toronto, Toronto, Canada
| | - Arun K Tiwari
- Neurogenetics Section, Centre for Addiction and Mental Health, Toronto, Canada
| | - Robert D Levitan
- Institute of Medical Science, University of Toronto, Toronto, Canada; Department of Psychiatry, University of Toronto, Toronto, Canada; Mood and Anxiety Program, Centre for Addiction and Mental Health, Toronto, Canada
| | - Sara Piran
- Faculty of Medicine, University of Ottawa, Ottawa, Canada
| | - Andrew W Bergen
- Center for Health Sciences, SRI International, Menlo Park, CA, USA
| | - Walter H Kaye
- Department of Psychiatry, University of California, San Diego, CA, USA
| | - Hakon Hakonarson
- Joseph Stokes Jr. Research Institute, The Children's Hospital of Philadelphia, Philadelphia, PA, USA
| | - Kai Wang
- Department of Psychiatry, University of Southern California, Los Angeles, CA, USA
| | - Wade H Berrettini
- Department of Psychiatry, Center of Neurobiology and Behavior, University of Pennsylvania, Philadelphia, PA, USA
| | - Harry A Brandt
- Department of Psychiatry, Sheppard Pratt Health System, Towson, MD, USA
| | - Cynthia M Bulik
- Department of Psychiatry, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA; Department of Nutrition, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA
| | - Steven Crawford
- Department of Psychiatry, Sheppard Pratt Health System, Towson, MD, USA
| | - Scott Crow
- Department of Psychiatry, University of Minnesota, Minneapolis, MN, USA
| | - Manfred M Fichter
- Department of Psychiatry, University of Munich (LMU), Munich, Germany; Roseneck Hospital for Behavioral Medicine, Prien, Germany
| | - Katherine A Halmi
- Department of Psychiatry, Weill Cornell Medical College, New York, NY, USA
| | | | - Pamela K Keel
- Department of Psychology, Florida State University, Tallahassee, FL, USA
| | - Kelly L Klump
- Department of Psychology, Michigan State University, East Lansing, MI, USA
| | - Pierre Magistretti
- Brain Mind Institute, Ecole Polytechnique Fédérale de Lausanne, Lausanne, Switzerland
| | - James E Mitchell
- Department of Clinical Neuroscience, University of North Dakota School of Medicine and Health Sciences, Grand Forks, ND, USA; Neuropsychiatric Research Institute, Fargo, ND, USA
| | - Michael Strober
- Department of Psychiatry, Semel Institute for Neuroscience and Human Behavior, David Geffen School of Medicine, University of California, Los Angeles, CA, USA
| | - Laura M Thornton
- Department of Psychiatry, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA
| | - Janet Treasure
- Department of Academic Psychiatry, King's College London, Institute of Psychiatry, London, United Kingdom
| | - D Blake Woodside
- Department of Psychiatry, University of Toronto, Toronto, Canada; Eating Disorders Program, Toronto General Hospital, Toronto, Canada
| | - Joanne Knight
- Institute of Medical Science, University of Toronto, Toronto, Canada; Department of Psychiatry, University of Toronto, Toronto, Canada; Neurogenetics Section, Centre for Addiction and Mental Health, Toronto, Canada
| | - James L Kennedy
- Institute of Medical Science, University of Toronto, Toronto, Canada; Department of Psychiatry, University of Toronto, Toronto, Canada; Neurogenetics Section, Centre for Addiction and Mental Health, Toronto, Canada.
| |
Collapse
|
3
|
Gutiérrez E, Churruca I, Zárate J, Carrera O, Portillo MP, Cerrato M, Vázquez R, Echevarría E. High ambient temperature reverses hypothalamic MC4 receptor overexpression in an animal model of anorexia nervosa. Psychoneuroendocrinology 2009; 34:420-9. [PMID: 19022583 DOI: 10.1016/j.psyneuen.2008.10.003] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/18/2008] [Revised: 09/29/2008] [Accepted: 10/08/2008] [Indexed: 02/07/2023]
Abstract
The potential involvement of the melanocortin system in the beneficial effects of heat application in rats submitted to activity-based anorexia (ABA), an analogous model of anorexia nervosa (AN), was studied. Once ABA rats had lost 20% of body weight, half of the animals were exposed to a high ambient temperature (HAT) of 32 degrees C, whereas the rest were maintained at 21 degrees C. Control sedentary rats yoked to ABA animals received the same treatment. ABA rats (21 degrees C) showed increased Melanocortin 4 (MC4) receptor and Agouti gene Related Peptide (AgRP) expression, and decreased pro-opiomelanocortin (POMC) mRNA levels (Real Time PCR), with respect to controls. Heat application increased weight gain and food intake, and reduced running rate in ABA rats, when compared with ABA rats at 21 degrees C. However, no changes in body weight and food intake were observed in sedentary rats exposed to heat. Moreover, heat application reduced MC4 receptor, AgRP and POMC expression in ABA rats, but no changes were observed in control rats. These results indicate that hypothalamic MC4 receptor overexpression could occur on the basis of the characteristic hyperactivity, weight loss, and self-starvation of ABA rats, and suggest the involvement of hypothalamic melanocortin neural circuits in behavioural changes shown by AN patients. Changes in AgRP and POMC expression could represent an adaptative response to equilibrate energy balance. Moreover, the fact that HAT reversed hypothalamic MC4 receptor overexpression in ABA rats indicates the involvement of brain melanocortin system in the reported beneficial effects of heat application in AN. A combination of MC4 receptor antagonists and heat application could improve the clinical management of AN.
Collapse
Affiliation(s)
- E Gutiérrez
- Departments of Clinical Psychology and Psychobiology, University of Santiago de Compostela, Spain
| | | | | | | | | | | | | | | |
Collapse
|