ETHANOL ANTICIPATION ENHANCES DOPAMINE EFFLUX IN THE NUCLEUS-ACCUMBENS OF ALCOHOL-PREFERRING (P) BUT NOT WISTAR RATS

It has been argued that the anticipation of ethanol consumption can ac tivate reinforcement substrates involved in alcohol-seeking behavior, To test this hypothesis nucleus accumbens (NAc) dopamine (DA) efflux w as monitored in alcohol-preferring (P) and Wistar rats. Rats from each line were divided into two groups: one trained to self-administer 0.0 5% saccharin and the other trained to self-administer 10% (w/v) ethano l. On the test day dopamine efflux was monitored in all animals during saccharin self-administration. In ethanol-expecting P rats, self-admi nistration of saccharin produced a significant elevation in extracellu lar DA (150% of baseline within the first 15-20 min), In contrast, a s ignificant increase in extracellular DA was only observed during the f inal 30 min of the test session in ethanol-expecting Wistar rats self- administering saccharin. The self-administration of saccharin in anima ls expecting the sweetener failed to elevate extracellular DA in both strains. Overall, these results suggest that the mere expectation of e thanol availability enhances the efflux of DA in the NAc of the P, but not the Wistar rat, which may play a role in the initiation or mainte nance of ethanol seeking behavior in the P line.