DELAYED ETHANOL EFFECTS ON PHYSIOLOGICAL AND BEHAVIORAL INDEXES IN THE RAT

The purpose of this project was to examine time-dependent initial and delayed behavioral and physiological effects of acute and chronic etha nol administration in rats. Experiment 1 compared the 24-h changes in temperature (rectal probe), activity (open field), and analgesia (tail -flick test) induced by an acute 4-g/kg dose of ethanol before and aft er a chronic regimen of ethanol. Initial hypothermic, hypoactivity, an d analgesic effects were found, but no delayed secondary effects were evident and tolerance occurred only for the analgesic measure. Experim ent 2 examined dose-dependent, 48-h changes in temperature and activit y (monitored simultaneously and continuously via implanted telemetry s ensors) before and after a daily regimen of ethanol injections. Acute ethanol produced dose-dependent initial hypothermic and hypoactivity e ffects followed by a delayed hyperthermic effect. Following the chroni c ethanol regimen, tolerance to all effects was evident. The results w ere discussed in terms of methodological differences in the two experi ments and the possible basis for the delayed ethanol effects. There is a strong suggestion that the secondary hyperthermic effect represents not a rebound, homeostatic phenomenon restricted to the temperature s ystem, but rather an ''artifact'' due to a disruption of the circadian rhythm, resulting in an absence of the normal reduction in activity s een during the light cycle.