Active sleep in cold-exposed infant Norway rats and Syrian golden hamsters: the role of brown adipose tissue thermogenesis.

It was previously hypothesized that brown adipose tissue (BAT) thermogenesis helps to maintain high rates of myoclonic twitching during cold exposure in infant rats (M. S. Blumberg & M. A. Stolba, 1996). To test this hypothesis, the sensitivity of twitching to various levels of cold exposure was assessed in week-old rats that were untreated or whose BAT thermogenesis was inhibited using a ganglionic blocker. Because week-old golden hamsters do not exhibit BAT thermogenesis, their sleep behaviors during cold exposure also were examined. Additional investigations in infant rats were conducted in which supplemental heat was provided to the interscapular region using a thermode and in which BAT was activated pharmacologically in ganglionically blocked pups. The results support the hypothesis that myoclonic twitching is sensitive to the prevailing air temperature and the activation of BAT thermogenesis.