A COMPARISON OF THE EFFECTS OF THE OPIOID ANTAGONISTS NALTREXONE, NALTRINDOLE, AND BETA-FUNALTREXAMINE ON ETHANOL-CONSUMPTION IN THE RAT

The effects of the universal opioid antagonist naltrexone were compare d to the delta-selective opioid antagonist naltrindole and the mu-sele ctive opioid antagonist beta-funaltrexamine on ethanol consumption in the absence of food or fluid deprivation using a limited access proced ure in Wistar rats. Both naltrexone, at doses of 0.1, 0.25, 0.5, 1.0, 3.0, and 10 mg/kg, and beta-funaltrexamine, at doses of 5.0 and 20.0 m g/kg, significantly decreased consumption of a 6% ethanol solution com pared to saline control groups. Naltrindole, at doses of 5.0 and 15.0 mg/kg, failed to significantly reduce ethanol consumption. In addition , the highest doses of naltrexone, which antagonize delta as well as m u-opioid receptors, did not differ significantly from the lowest doses in their ability to reduce ethanol consumption. These data suggest th at ethanol consumption using the limited access paradigm in the outbre d rat is modulated by mu rather than delta-opioid receptors. Although this is not consistent with other data showing that delta antagonists decrease ethanol consumption, it is suggested that these difference ma y be related to the alcohol-preferring rats used in those experiments. (C) 1998 Elsevier Science Inc.