CONTRIBUTION OF THE OPIOID SYSTEM TO ALCOHOL AVERSION AND ALCOHOL-DRINKING BEHAVIOR

The effect of blocking delta opioid receptors on alcohol aversion was examined in female alcohol-preferring (P) rats using a conditioned tas te aversion (CTA) paradigm. In experiment 1, alcohol naive P rats were given i.p injections of 0.5, 1.0 or 1.5 g alcohol/kg BW or saline, pa ired with consumption of a banana-flavored solution during 5 condition ing trials. Alcohol in a dose of 0.5 g/kg was not aversive while the t wo higher doses (1.0 and 1.5 g/kg) were both aversive in the CTA parad igm. In experiment 2, the effect of the selective delta opioid recepto r antagonist, naltrindole (NTI), on alcohol aversion was examined. Rat s were pretreated with NTI in doses of 2.5, 5.0, 10.0 or 20.0 mg/kg be fore conditioning using the nonaversive dose of alcohol from Experimen t 1. As in experiment 1, the 0.5 g/kg dose of alcohol did not produce a CTA. Administration of NTI alone in doses of 2.5, 5.0 or 10.0 mg/kg did not produce a CIA. However, when the nonaversive dose of alcohol ( 0.5 g/kg) was combined with NTI in a dose of either 5.0 or 10.0 mg/kg, an aversion to alcohol was seen. The highest dose of NTI (20 mg/kg) p roduced a CTA when given either alone and in combination with alcohol. The results indicate that blocking the action of opioid peptides at t he delta opioid receptor can make a nonaversive dose of alcohol aversi ve which suggests that opioid peptides, acting via the delta opioid re ceptor, play an important role in regulating alcohol aversion.