Effect of chronic intoxication and naloxone on the ethanol-induced increase in plasma corticosterone

Abstract

Ethanol (0.5–4.0 g/kg) induced an immediate, dose-dependent rise in plasma corticosterone in the conscious, undisturbed male rat. Chronic intoxication for at least two days resulted in tolerance to this effect. Chronic intoxication also significantly elevated the morning trough levels of this steroid. Co-administration of naloxone (1 mg/kg) prevented the development of tolerance to the immediate stimulatory effect of ethanol but did not alter the elevated trough levels of corticosterone. Naloxene (1 mg/kg) did not alter the stimulatory effect of ethanol on corticosterone in ethanol-naive animals. These data suggest that the process of tolerance development to the ethanol-induced rise in corticosterone is mediated by an opiate receptor. Alterations in the ability of ethanol to stimulate corticosterone secretion may be a useful endpoint for future studies of tolerance development to ethanol.