EFFECT OF ETHANOL DRINKING AND NALTREXONE ON SUBSEQUENT DRINKING IN RATS

The effects of several days of oral ethanol drinking paired with naltr exone (NTX) on subsequent ethanol drinking were investigated in rats. We hypothesized that repeated pairings of NTX combined with forced ora l ethanol intake would extinguish ethanol drinking so that when NTX in jections were terminated, voluntary oral ethanol drinking would be sup pressed. Thirty-two male, Long-Evans rats were provided with alternate days of either 8% ethanol solution or water as the sole source of flu id. Intraperitoneal injections of 0, 2.5, or 5.0 mg of NTX hydrochlori de were administered on the ethanol days. Following the termination of injections, rats were returned to unrestricted access to water and et hanol and 24-h measurements of fluid intake were recorded. NTX decreas ed ethanol intake 4 h, but not 24 h, after NTX injections. Despite the consumption of significant amounts of ethanol during NTX treatment, t here was no change in voluntary oral ethanol intake patterns after NTX injections were terminated (reinstatement of voluntary ethanol drinki ng). Thus, NTX's reduction in ethanol intake was limited in duration a nd did not result in long-term extinction of ethanol drinking behavior . (C) 1997 Elsevier Science Inc.