Acute ethanol administration increases cerebrocortical and hippocampal corticosterone levels but does not alter allopregnanolone levels in C57BL/6J and DBA/2J mice

The ethanol-induced increase in brain allopregnanolone levels in rats contributes to sensitivity to ethanol's behavioral effects. However, ethanol's effects on allopregnanolone may differ across species. We investigated the effects of acute ethanol administration on allopregnanolone, progesterone and corticosterone levels in cerebral cortex and hippocampus of C57BL/6J and DBA/2J mice, two inbred strains with different alcohol sensitivity. Male C57BL/6J and DBA/2J mice received ethanol (1, 2, 3 or 4 g/kg, i.p.) or saline and were euthanized 1 hour later. For the time-course study, ethanol (2 g/kg) was administered 15, 30, 60 and 120 minutes before euthanasia. Steroids were measured by radioimmunoassay. Acute ethanol administration did not alter cerebrocortical and hippocampal levels of allopregnanolone and progesterone in these strains at any of the doses and time points examined. Acute ethanol dose-dependently increased cerebrocortical corticosterone levels by 319%, 347% and 459% in C57BL/6J mice at 2, 3 and 4 g/kg, and by 371%, 507%, 533% and 692% in DBA/2J mice at 1, 2, 3 and 4 g/kg, respectively. Similar changes were observed in the hippocampus. Ethanol's effects on cerebrocortical corticosterone levels were also time-dependent in both strains. Morphine administration (5 mg/kg) increased cerebrocortical allopregnanolone levels in C57BL/6J (+77%) and DBA/2J mice (+81%), suggesting that the impairment in brain neurosteroidogenesis may be specific to ethanol. These results underline important species differences on ethanol-induced brain neurosteroidogenesis. Acute ethanol increases corticosterone levels but does not alter allopregnanolone and progesterone concentrations in cerebral cortex and hippocampus of C57BL/6J and DBA/2J mice.