APStracts 2:0021R, 1995.

Changes in circadian rhythms of body temperature and sleep in old rats. Li, Hua, and Evelyn Satinoff. University of Illinois at Urbana-Champaign, Champaign, IL 61820 , Department of Psychology, Department of Physiology, Neuroscience Program

APStracts 2:0021R, 1995.

We examined the relationship between circadian rhythms of body temperature (CTR) and sleep in adult and old female rats. Body temperature was recorded telemetrically for months and sleep for 24 hr in a 12:12 LD cycle at 23 degrees C. Some old rats had robust CTRs (old good), and some had unstable or absent CTRs (old unstable). Compared to adult rats and old good rats, old unstable rats had lower daily mean body temperatures, smaller daily amplitudes, and an advanced CTR phase. Old good rats matched adult rats on all measures. Old good rats showed normal circadian parameters of sleep whereas in old unstable rats the amplitudes of both slow-wave-sleep (SWS) and rapid -eye-movement sleep (REMS) were decreased although the amounts were equivalent. Rhythmic parameters of sleep correlate well with the stability or instability of the CTR while homeostatic regulation of both REMS and SWS do not seem to be impaired during aging and are independent of the stability of the CTR.

Received 31 May 1994; accepted in final form 22 January 22 1995.
APS Manuscript Number R296-4.
Article publication pending Am. J. Physiol. (Regulatory Integrative
Comp. Physiology).
ISSN 1080-4757 Copyright 1995 The American Physiological Society.
Published in APStracts on 25 February 1995.