EFFECT OF MU-OPIOID RECEPTOR BLOCKADE ON ALCOHOL INTAKE IN RATS BRED FOR HIGH ALCOHOL-DRINKING

Beta-funaltrexamine (beta-FNA), a selective mu opioid receptor antagon ist, when administered in doses of 10.0, 15.0, and 20.0 mg/kg b.wt., d ecreased alcohol but not water intake in a dose-dependent manner in ra ts selectively bred for high alcohol intake (HAD line). Beta-FNA also suppressed the intake of a saccharin solution containing alcohol witho ut altering the intake of a similar solution without alcohol. The resu lts suggest that beta-FNA may prove useful as a pharmacotherapeutic ag ent for the treatment of alcohol dependence. In a second study, pituit ary beta-endorphin gene expression (proopiomelanocortin or POMC messin ger ribonucleic acid-mRNA) was compared in another pair of rat lines s electively bred for high or low alcohol intake (alcohol preferring or P and alcohol-nonpreferring or NP lines). A repeated alcohol challenge (1.0 g/kg b.wt./day, IP for 4 days) produced a greater increase in PO MC mRNA in the anterior and neurointermediate lobes of the pituitary o f P rats compared with NP rats. The results suggest that a genetic pre disposition toward high alcohol drinking may be associated with increa sed responsiveness of the opioid system to alcohol. (C) 1998 Elsevier Science Inc.