Phase-response curve for ethanol: alterations in circadian rhythms of temperature and activity in rats.
Circadian rhythms of core body temperature and general activity in Sprague-Dawley rats were monitored for 21 days using remote radiotelemetry to examine acute and sustained effects of 0 (saline) 1.0, and 2.0 g/kg ethanol injections administered at four different times of day. Ethanol produced dose-dependent and statistically significant hypothermia and hypoactivity when injected at 0100, 0700, 1300, and 1900 h; however, the magnitude of the hypothermic effect was greatest at the 1900-h injection time. Cosinor analyses revealed persistent alterations in both activity and temperature rhythms, which lasted for at least 48 h postinjection. Ethanol significantly shortened the period of activity rhythms when injected in either 1.0 or 2.0 g/kg doses at 0700 and 1300 h, and produced similar period-shortening effects on temperature rhythms at 1300 and 1900 h. The acrophase of the activity rhythm was significantly phase delayed by 1.0 g/kg ethanol at 0700 h, while the acrophase of temperature was significantly phase advanced by 2.0 g/kg ethanol at 0100 h, but significantly phase delayed by the same dose administered at 1300 h. A statistically significant and dose-dependent reduction in the amplitude of the body temperature rhythm was observed at the 1900-h administration time. There were no differences in the MESOR (Midline Estimating Statistic of Rhythm; i.e., rhythm-adjusted mean value) of either temperature or activity circadian rhythms as a function of ethanol treatment at any dose.
Department of Psychiatry & Behavioral Sciences, University of Oklahoma Health Sciences Center, Oklahoma City 73190-3000, USA.
T J
TJ
Baird
R J
RJ
Briscoe
M
M
Vallett
S A
SA
Vanecek
F A
FA
Holloway
D V
DV
Gauvin
D000210:Acute-Phase Reaction; D000818:Animals; D001831:Body Temperature / Q000187:drug effects*; D002492:Central Nervous System Depressants / Q000494:pharmacology*; D002940:Circadian Rhythm / Q000187:drug effects*; D000431:Ethanol / Q000494:pharmacology*; D008297:Male; D009043:Motor Activity / Q000187:drug effects*; D051381:Rats; D017207:Rats, Sprague-Dawley; D013997:Time Factors
D002492:Central Nervous System Depressants; D000431:Ethanol