Establishment of the ethanol-induced place preference in rats.

Ethanol failed to induce a place preference in both 15 and 50 min conditioning schedules in free-feeding and in food deprived rats. Acetaldehyde, the primary metabolic product of ethanol, induced a weak place aversion, dose-dependently. Ethanol combined with pyrazole (an alcohol dehydrogenase inhibitor) significantly induced a place preference in rats (ethanol; 300 mg/kg, i.p., pyrazole; 100 mg/kg, i.p.) in a 50 min conditioning schedule. The ethanol (300 mg/kg) combined with pyrazole (100 mg/kg)-induced place preference was antagonized or reduced by 5-HT3 antagonists (MDL72222, ICS205-930). These results suggest that a blockade of ethanol metabolism is very important for development of the ethanol-induced place preference in rats, and that the ethanol-induced place preference may be mediated by the mesolimbic dopamine system through 5-HT3 receptors.