Document Detail


Peripheral ghrelin stimulates feeding behavior and positive energy balance in a sciurid hibernator.
MedLine Citation:
PMID:  21310157     Owner:  NLM     Status:  MEDLINE    
Abstract/OtherAbstract:
Hibernators exhibit a robust circannual cycle of body mass gain and loss primarily mediated by food intake, but the pathways controlling food intake in these animals have not been fully elucidated. Ghrelin is an orexigenic hormone that increases feeding in all mammals studied so far, but has not until recently been studied in hibernators. In other mammals, ghrelin stimulates feeding through phosphorylation and activation of AMP-activated protein kinase (AMPK). Activation of AMPK phosphorylates and deactivates acetyl Co-A carboxylase (ACC), a committed step in fatty acid synthesis. In order to determine the effects of exogenous ghrelin on food intake and metabolic factors (i.e. non-esterified fatty acids (NEFAs), and hypothalamic AMPK and ACC) in hibernators, ghrelin was peripherally injected into ground squirrels in all four seasons. Changes in food intake and body mass were recorded over a 2-6 hour period post injections, and squirrels were euthanized. Brains and blood were removed, and Western blots were performed to determine changes in phosphorylation of hypothalamic AMPK and ACC. A colorimetric assay was used to determine changes in concentration of serum NEFAs. We found that food intake, body mass, and locomotor activity significantly increased with ghrelin injections versus saline-injected controls, even in animals injected during their aphagic winter season. Injected ghrelin was correlated with increased phosphorylation of AMPK, but didn't have an effect on ACC in winter. Ghrelin-injected animals also had increased levels of serum NEFAs compared with saline controls. This study is the first to show an effect of injected ghrelin on a hibernator.
Authors:
Jessica E Healy; Jenna L Bateman; Cara E Ostrom; Gregory L Florant
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Publication Detail:
Type:  Journal Article; Research Support, N.I.H., Extramural; Research Support, Non-U.S. Gov't     Date:  2011-02-17
Journal Detail:
Title:  Hormones and behavior     Volume:  59     ISSN:  1095-6867     ISO Abbreviation:  Horm Behav     Publication Date:  2011 Apr 
Date Detail:
Created Date:  2011-04-22     Completed Date:  2011-08-15     Revised Date:  2013-06-30    
Medline Journal Info:
Nlm Unique ID:  0217764     Medline TA:  Horm Behav     Country:  United States    
Other Details:
Languages:  eng     Pagination:  512-9     Citation Subset:  IM    
Copyright Information:
Copyright © 2011 Elsevier Inc. All rights reserved.
Affiliation:
Department of Biology, Colorado State University, Fort Collins, CO 85023, USA. jehealy@email.arizona.edu
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MeSH Terms
Descriptor/Qualifier:
Acetyl-CoA Carboxylase / metabolism
Adenylate Kinase / metabolism
Analysis of Variance
Animals
Blotting, Western
Body Weight / drug effects,  physiology
Eating / drug effects,  physiology
Energy Metabolism / drug effects*,  physiology
Fatty Acids, Nonesterified / metabolism
Feeding Behavior / drug effects*,  physiology
Ghrelin / pharmacology*
Hypothalamus / drug effects*,  metabolism
Motor Activity / drug effects*,  physiology
Phosphorylation / drug effects
Random Allocation
Sciuridae
Grant Support
ID/Acronym/Agency:
DK 067017-3/DK/NIDDK NIH HHS; R25 DK067017-03/DK/NIDDK NIH HHS
Chemical
Reg. No./Substance:
0/Fatty Acids, Nonesterified; 0/Ghrelin; EC 2.7.4.3/Adenylate Kinase; EC 6.4.1.2/Acetyl-CoA Carboxylase
Comments/Corrections

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