title: Cholesterol and lipoprotein dynamics in a hibernating mammal.
abstract: Hibernating mammals cease feeding during the winter and rely primarily on stored lipids to fuel alternating periods of torpor and arousal. How hibernators manage large fluxes of lipids and sterols over the annual hibernation cycle is poorly understood. The aim of this study was to investigate lipid and cholesterol transport and storage in ground squirrels studied in spring, summer, and several hibernation states. Cholesterol levels in total plasma, HDL and LDL particles were elevated in hibernators compared with spring or summer squirrels. Hibernation increased plasma apolipoprotein A-I expression and HDL particle size. Expression of cholesterol 7 alpha-hydroxylase was 13-fold lower in hibernators than in active season squirrels. Plasma triglycerides were reduced by fasting in spring but not summer squirrels. In hibernators plasma β-hydroxybutyrate was elevated during torpor whereas triglycerides were low relative to normothermic states. We conclude that the switch to a lipid-based metabolism during winter, coupled with reduced capacity to excrete cholesterol creates a closed system in which efficient use of lipoproteins is essential for survival.
authors.affiliation: Department of Comparative Biosciences, University of Wisconsin, Madison, Wisconsin, United States of America.
authors.forename: Jessica P
authors.initials: JP
authors.lastname: Otis
authors.forename: Daisy
authors.initials: D
authors.lastname: Sahoo
authors.forename: Victor A
authors.initials: VA
authors.lastname: Drover
authors.forename: Chi-Liang Eric
authors.initials: CL
authors.lastname: Yen
authors.forename: Hannah V
authors.initials: HV
authors.lastname: Carey
mesh_terms: D020155:3-Hydroxybutyric Acid / Q000097:blood; D000217:Acyltransferases / Q000378:metabolism; D000818:Animals; D001189:Aryl Hydrocarbon Hydroxylases / Q000235:genetics / Q000378:metabolism; D001646:Bile / Q000378:metabolism; D001831:Body Temperature / Q000502:physiology; D002784:Cholesterol / Q000097:blood*; D005227:Fatty Acids / Q000097:blood; D005260:Female; D005786:Gene Expression Regulation; D006605:Hibernation / Q000235:genetics / Q000502:physiology*; D006903:Hydroxymethylglutaryl CoA Reductases / Q000235:genetics / Q000378:metabolism; D008074:Lipoproteins / Q000097:blood*; D008297:Male; D008954:Models, Biological; D009928:Organ Specificity; D012589:Sciuridae / Q000097:blood* / Q000235:genetics / Q000502:physiology*; D012621:Seasons; D013250:Steroid Hydroxylases / Q000235:genetics / Q000378:metabolism; D014280:Triglycerides / Q000097:blood
chemical_list: D005227:Fatty Acids; D008074:Lipoproteins; D014280:Triglycerides; D002784:Cholesterol; D006903:Hydroxymethylglutaryl CoA Reductases; D013250:Steroid Hydroxylases; D001189:Aryl Hydrocarbon Hydroxylases; C029009:steroid hormone 7-alpha-hydroxylase; D000217:Acyltransferases; C021802:2-acylglycerol O-acyltransferase; D020155:3-Hydroxybutyric Acid