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7017022 
Journal Article 
Regulation of metabolism during hibernation in brown bears (Ursus arctos): Involvement of cortisol, PGC-1 alpha and AMPK in adipose tissue and skeletal ifyrigir muscle 
Vella, CA; Nelson, OL; Jansen, HT; Robbins, CT; Jensen, AE; Constantinescu, S; Abbott, MJ; Turcotte, LP; , 
2020 
Yes 
Comparative Biochemistry and Physiology - Part A: Molecular and Integrative Physiology
ISSN: 1095-6433
EISSN: 1531-4332 
ELSEVIER SCIENCE INC 
NEW YORK 
31669707 
WOS:000508489600001 
The purpose of this study was to investigate changes in expression of known cellular regulators of metabolism during hyperphagia (Sept) and hibernation (Jan) in skeletal muscle and adipose tissue of brown bears and determine whether signaling molecules and transcription factors known to respond to changes in cellular energy state are involved in the regulation of these metabolic adaptations. During hibernation, serum levels of cortisol, glycerol, and triglycerides were elevated, and protein expression and activation of AMPK in skeletal muscle and adipose tissue were reduced. mRNA expression of the co-activator PGC-1 alpha was reduced in all tissues in hibernation whereas mRNA expression of the transcription factor PPAR-alpha was reduced in the vastus lateralis muscle and adipose tissue only. During hibernation, gene expression of ATGL and CD36 was not altered; however, HSL gene expression was reduced in adipose tissue. During hibernation gene expression of the lipogenic enzyme DGAT in all tissues and the expression of the FA oxidative enzyme LCAD in the vastus lateralis muscle were reduced. Gene and protein expression of the glucose transporter GLUT4 was decreased in adipose tissue in hibernation. Our data suggest that high cortisol levels are a key adaptation during hibernation and link cortisol to a reduced activation of the AMPK/PGC-l alpha/PPAR-alpha axis in the regulation of metabolism in skeletal muscle and adipose tissue. Moreover, our results indicate that during this phase of hibernation at a time when metabolic rate is significantly reduced metabolic adaptations in peripheral tissues seek to limit the detrimental effects of unduly large energy dissipation.