Female rats release more corticosterone than males in response to alcohol: influence of circulating sex steroids and possible consequences for blood alcohol levels.

The hypothalamic-pituitary-adrenal (HPA) axis of female rats is more responsive to a variety of stimuli than that of males. Proestrous females are also reported to release more ACTH and corticosterone in response to restraint stress than females at other stages of the estrous cycle. Finally, blood alcohol levels (BALs) reached in response to a standard dose of alcohol also indicate the presence of a gender specificity, with females exhibiting higher BALs than males. The aim of this study was therefore 2-fold: first, we investigated the influence of gender on the ability of alcohol to increase plasma ACTH and corticosterone secretion in the rat. Second, we tested the hypothesis that corticosterone alters alcohol metabolism and asked whether this might represent a mechanism underlying the sex difference in BALs. We observed that compared with intact males, intact females taken at random stages of the estrous cycle secreted significantly (p < 0.01) more ACTH and corticosterone in response to alcohol (0.2-1.8 g/kg). Within females, the intraperitoneal administration of alcohol was followed by higher plasma ACTH and corticosteroids levels during proestrus and estrus, compared with diestrus. Removal of circulating sex steroids abolished the gender difference in terms of ACTH secretion, but ovariectomized females still released more corticosterone than castrated males in response to 0.6 and 1.8 g alcohol/kg. This difference could not be explained by a sex-related component of pituitary responsiveness to corticotropin-releasing factor.(ABSTRACT TRUNCATED AT 250 WORDS)