Effects of fluoxetine on the intragastric self-administration of ethanol in the alcohol preferring P line of rats.

Rats of the alcohol-preferring P line (n = 7) were trained to self-administer ethanol (20% v/v) and water via an intragastric IG catheter. Food was available ad lib. Ethanol intakes averaged approximately 5-6 g/kg body wt./day. Treatment with the serotonin (5-HT) uptake inhibitor fluoxetine (10 mg/kg/day; IG) for seven consecutive days produced a marked decrease in ethanol self-administration on the first day, which was sustained throughout the seven days of treatment to values as low as 1 g/kg/day. Concomitant with the decrease in ethanol intake, the self-infusion of water gradually increased during the period of fluoxetine treatment. Total caloric intake (ethanol plus food) was moderately reduced during fluoxetine treatment; the decrease in food consumption was consistent but not statistically significant. When fluoxetine treatment was terminated, ethanol self-administration quickly returned to the prefluoxetine levels, while water intake began to decrease. Since no ethanol was consumed orally, the IG ethanol was not self-administered for its taste or smell, but apparently for its postingestive pharmacological effects. The robust reduction of ethanol self-infusion that occurred with fluoxetine treatment suggests that the 5-HT systems are involved in the reinforcing effects of ethanol in the P line of rats.