Effect of elevated ambient temperature on sleep, eeg spectra, hypothalamic
temperature and cortical temperature in the rat.
Gao, Bo, Paul Franken, Irene Tobler, and Alexander A. Borb[acute]ely.
Institute of Pharmacology, University of Z[umlaut]urich, CH-8057
Z[umlaut]urich, Switzerland
APStracts 2:0011R, 1995.
To examine the relation between sleep and brain temperature in the rat, the
vigilance states, spectral power density of the electroencephalogram (EEG),
hypothalamic temperature (Thy) and cortical temperature (Tcr) were recorded
for 3 days. A one-day rise of ambient temperature from 23 degrees C to 30
degrees C did not affect the percentage of waking, non-rapid-eye-movement
sleep (NREMS) and REMS, but increased EEG slow-wave activity in NREMS in the
12-hour dark period. Thy was invariably higher than Tcr, but at 30 degrees C
the difference diminished due to a rise in Tcr. In contrast to Tcr, Thy was
only slightly increased at 30 degrees C, and only during sleep and in the dark
period. Although the temperatures changed largely in parallel at vigilance
state transitions, Tcr rose more rapidly than Thy at NREMS - REMS transitions,
and more slowly at NREMS - waking transitions. Thy declined more rapidly than
Tcr at waking - NREMS transitions, and more slowly at REMS - NREMS
transitions. The results are consistent with a central role of the
hypothalamus in the activation and deactivation of the waking state.
Received 16 May 1994; accepted in final form 17 January 1995.
APS Manuscript Number R260-4.
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.