ACETATE-1-C14UTILIZATION BY BROWN FAT FROM HAMSTERS IN COLD EXPOSURE AND HIBERNATION

Abstract

The in vitro conversion of acetate-1-C14to C14O2and C14-lipid by the interscapular and cervical brown fat depots of cold-exposed golden hamsters was measured. Tissue samples were taken from animals after 48 hours, 3 weeks, and 6–8 weeks in the cold, in hibernation, and arousing from hibernation and immediately after arousal. There was a depression in C14O2production by cervical tissue after 48 hours in the cold, and by interscapular tissue after 3 weeks in the cold. C14O2production by both depots remained low throughout acclimation, hibernation, and arousal. C14-Lipid production by both depots increased after 48 hours in the cold and remained high during acclimation. C14-Lipid production was depressed during hibernation and arousal, with recovery to acclimated levels at the end of arousal in the interscapular, but not in the cervical depot. Cervical brown fat had a higher conversion to both C14O2and C14-lipid than interscapular brown fat. Qualitatively, but not quantitatively, brown fat behaved similarly to white fat. It was concluded that increased lipogenic capacity is not a primary response of brown fat to cold exposure of the animal, but that some other pathway becomes highly active.