Antagonism of corticotropin-releasing factor attenuates the enhanced responsiveness to stress observed during protracted ethanol abstinence

Abstract

One of the most critical attributes of chronic abstinence from alcohol is a state of anxiety, which can lead to mood disturbances and negative affect that can last for months or even years in alcoholics. Within hours after their final exposure to ethanol in experimental conditions, laboratory animals also exhibit an anxiety-like state. This state is accompanied by an enhanced stress response and can persist for weeks after withdrawal. One possible mechanism underlying these behavioral changes observed weeks after withdrawal is increased corticotropin-releasing factor (CRF) activity. In the present study, we sought to examine the role of CRF in the regulation of behavior in the elevated plus-maze during protracted abstinence by using intracerebroventricular administration of the CRF receptor antagonist [D-Phe(12),Nle(21,38),CalphaMeLeu(37)]rCRF((12-41)) (D-Phe-CRF((12-41))). Rats were surgically implanted with a guide cannula aimed at the lateral ventricles and subsequently fed a nutritionally complete ethanol [10% (vol./vol.)] or control liquid diet for 21 days. Rats were further divided into groups receiving microinjections of D-Phe-CRF((12-41)) or vehicle and 15 min of restraint stress, or D-Phe-CRF((12-41)) or vehicle and no restraint. Six weeks after removal of the liquid diet, rats were injected and then placed in a restraint tube or returned to their home cages for 15 min before testing in the elevated plus-maze. Rats with a history of ethanol dependence explored the open arms of the plus-maze significantly less when exposed to restraint stress compared with findings for all other groups, an effect attenuated by pretreatment with D-Phe-CRF((12-41)). Results of the current experiment demonstrated that continuous exposure to ethanol over a 3-week period leads to an increased behavioral responsiveness to stress, which seems to be regulated by CRF.