title: Energy homeostasis regulatory peptides in hibernating grizzly bears.
abstract: Grizzly bears (Ursus arctos horribilis) are inactive for up to 6 months during hibernation. They undergo profound seasonal changes in food intake, body mass, and energy expenditure. The circa-annual regulation of metabolism is poorly understood. In this study, we measured plasma ghrelin, leptin, obestatin, and neuropeptide-Y (NPY) levels, hormones known to be involved in the regulation of energy homeostasis, in ten grizzly bears. Blood samples were collected during the active summer period, early hibernation and late hibernation. Plasma levels of leptin, obestatin, and NPY did not change between the active and the hibernation periods. Plasma total ghrelin and desacyl-ghrelin concentrations significantly decreased during the inactive winter period compared to summer levels. The elevated ghrelin levels may help enhance body mass during pre-hibernation, while the low plasma ghrelin concentrations during hibernation season may contribute to the maintenance of hypophagia, low energy utilization and behavioral inactivity. Our results suggest that ghrelin plays a potential role in the regulation of metabolic changes and energy homeostasis during hibernation in grizzly bears.
authors.affiliation: First Department of Internal Medicine, University of Szeged, Korányi fasor 8-10, H-6720 Szeged, Hungary. jgardi@vetmed.wsu.edu
authors.forename: János
authors.initials: J
authors.lastname: Gardi
authors.forename: O Lynne
authors.initials: OL
authors.lastname: Nelson
authors.forename: Charles T
authors.initials: CT
authors.lastname: Robbins
authors.forename: Eva
authors.initials: E
authors.lastname: Szentirmai
authors.forename: Levente
authors.initials: L
authors.lastname: Kapás
authors.forename: James M
authors.initials: JM
authors.lastname: Krueger
mesh_terms: D000818:Animals; D004734:Energy Metabolism / Q000187:drug effects* / Q000502:physiology*; D005260:Female; D054439:Ghrelin / Q000097:blood; D006605:Hibernation / Q000187:drug effects; D006706:Homeostasis / Q000187:drug effects / Q000502:physiology; D020738:Leptin / Q000097:blood; D008297:Male; D009478:Neuropeptide Y / Q000097:blood; D036361:Peptide Hormones / Q000097:blood* / Q000494:pharmacology* / Q000502:physiology; D001503:Ursidae / Q000097:blood / Q000378:metabolism / Q000502:physiology
chemical_list: D054439:Ghrelin; D020738:Leptin; D009478:Neuropeptide Y; D036361:Peptide Hormones