Temperature regulation in mice during withdrawal from ethanol dependence

Temperature regulation during withdrawal from ethanol dependence was studied in mice. Dependence was induced utilizing ethanol vapor inhalation combined with injections of pyrazole an alcohol dehydrogenase inhibitor. One control group received vehicle (0.9% NaCl); another received pyrazole (68.1 mg/kg) in vehicle. During withdrawal, mice were placed in a thermal gradient, with core temperature (T(c)) and preferred temperature (T(pref)) continuously recorded for 26 h. During the period of maximal withdrawal severity (4-10 h after removal from ethanol vapor), the withdrawal group was more active than controls. Withdrawal group T(c) [36.4 ± 0.1 (SE)°C] was similar to that of NaCl (36.2 ± 0.1°C) and pyrazole (36.3 ± 0.2°C) controls. Withdrawal group T(pref) (30.5 ± 0.5°C) was significantly lower than either NaCl (33.5 ± 0.3°C) or pyrazole (32.9 ± 0.5°C) controls. Analysis of covariance with activity as covariate indicated that the difference between T(c) and T(pref) was greater for the withdrawal group and was due to more than increased activity. Mice withdrawing at constant temperature (29.5°C) did not show T(c) different from that of controls. These results support the conclusion that regulated body temperature is not altered during withdrawal. We propose that the lower T(pref) of withdrawing mice represents a means of dissipating excess heat that is partly generated by the hypermetabolic state accompanying withdrawal from ethanol dependence.