Our previous study showed that the neurosteroids pregnenolone sulfate (PS) and epipregnanolone stimulated and blocked, respectively, the demonstration of chronic tolerance to the incoordinating effect of ethanol. The aim of the present study was to investigate the influence of three neurosteroids on the demonstration of tolerance to ethanol-induced hypothermia in mice using the rapid tolerance paradigm. The first experiment defined the doses of ethanol that did or did not induce rapid tolerance to ethanol-induced hypothermia. In the second, the influence of pretreatment of mice with PS (0.08 or 0.15 mg/kg, i.p.) or dehydroepiandrosterone sulfate (DHEAS; 0.15 or 0.20 mg/kg, i.p.) before ethanol (4.0 g/kg, i.p.) on rapid tolerance was studied. The third experiment examined the effect of allotetrahydrodeoxicorticosterone (ALLOT, 0.10 or 0.20 mg/kg, i.p.) before ethanol (4.0 g/kg, i.p.) on rapid tolerance. Results showed that pretreatment with PS or with DHEAS significantly facilitated the demonstration of rapid tolerance, whereas pretreatment with ALLOT interfered with the demonstration of tolerance to the hypothermic effect. (C) 2002 Elsevier Science Inc. All rights reserved.