Corticosteroid-binding globulin in ursids: binding affinities and nutritional regulation

Abstract

Event Abstract Back to Event Corticosteroid-binding globulin in ursids: binding affinities and nutritional regulation Brian A. Chow1, Seth W. Donahue2, Marc R. Cattet3, Gordon B. Stenhouse4 and Mathilakath M. Vijayan1* 1 University of Waterloo, Department of Biology, Canada 2 Michigan Technological University, United States 3 University of Saskatchewan, Canadian Wildlife Service, Canada 4 Foothills Research Institute, Canada The majority of corticosteroid in circulation in mammals is bound reversibly and with high affinity to a transport protein, corticosteroid-binding globulin (CBG). Cortisol bound to CBG is biologically unavailable to tissues, and consequently, CBG plays a key role in reducing free cortisol concentration and regulating the cellular actions of this hormone, including protecting tissues from potentially deleterious actions. However, little is known about either serum levels of CBG or its role in serum cortisol regulation in bears. Our lab previously reported differential expression of CBG between sexes in grizzly and polar bears, and between feeding and fasting polar bears by western immunoblotting. In this study, we report the development of a direct ELISA specific for grizzly bear CBG that accurately and reliably quantifies concentrations of this protein in grizzly, polar, and black bear sera. We have also calculated the equilibrium dissociation constants (Kd) of CBG in these species by Scatchard analysis. The black bear CBG showed the highest affinity for cortisol, followed by grizzly and polar bear CBG. The differences in Kd between these species may reflect differences in hormonal action in these species. With these data and total cortisol concentrations, which were measured with a commercial RIA, we calculated the free cortisol concentrations in the serum of these ursid species. We compared free serum cortisol concentrations between feeding and fasting animals to help establish the physiological role of cortisol in the seasonal metabolic adjustments of these animals. Acknowledgements Research funding provided by Natural Sciences and Engineering Research Council of Canada CRD grant and Alberta Innovation and Science grant. We would like to thank Dr. Rudy Boonstra and Brendan Delehanty (University of Toronto Scarborough) for their help with the saturation binding assay. Keywords: black bear, CBG, cortisol, ELISA, equilibrium dissociation constant, grizzly bear, polar bear Conference: NASCE 2011: The inaugural meeting of the North American Society for Comparative Endocrinology, Ann Arbor, United States, 13 Jul - 16 Jul, 2011. Presentation Type: Poster Topic: Stress hormones Citation: Chow BA, Donahue SW, Cattet MR, Stenhouse GB and Vijayan MM (2011). Corticosteroid-binding globulin in ursids: binding affinities and nutritional regulation. Front. Endocrinol. Conference Abstract: NASCE 2011: The inaugural meeting of the North American Society for Comparative Endocrinology. doi: 10.3389/conf.fendo.2011.04.00117 Copyright: The abstracts in this collection have not been subject to any Frontiers peer review or checks, and are not endorsed by Frontiers. They are made available through the Frontiers publishing platform as a service to conference organizers and presenters. The copyright in the individual abstracts is owned by the author of each abstract or his/her employer unless otherwise stated. Each abstract, as well as the collection of abstracts, are published under a Creative Commons CC-BY 4.0 (attribution) licence (https://creativecommons.org/licenses/by/4.0/) and may thus be reproduced, translated, adapted and be the subject of derivative works provided the authors and Frontiers are attributed. For Frontiers’ terms and conditions please see https://www.frontiersin.org/legal/terms-and-conditions. Received: 21 Jul 2011; Published Online: 09 Aug 2011. * Correspondence: Dr. Mathilakath M Vijayan, University of Waterloo, Department of Biology, Waterloo, Ontario, N2L3G1, Canada, mmvijaya@ucalgary.ca Login Required This action requires you to be registered with Frontiers and logged in. To register or login click here. Abstract Info Abstract The Authors in Frontiers Brian A Chow Seth W Donahue Marc R Cattet Gordon B Stenhouse Mathilakath M Vijayan Google Brian A Chow Seth W Donahue Marc R Cattet Gordon B Stenhouse Mathilakath M Vijayan Google Scholar Brian A Chow Seth W Donahue Marc R Cattet Gordon B Stenhouse Mathilakath M Vijayan PubMed Brian A Chow Seth W Donahue Marc R Cattet Gordon B Stenhouse Mathilakath M Vijayan Related Article in Frontiers Google Scholar PubMed Abstract Close Back to top Javascript is disabled. Please enable Javascript in your browser settings in order to see all the content on this page.