The effects of repeated alcohol exposure on the neurochemistry of the periadolescent nucleus accumbens septi.

Substance abuse is a major issue in today's society and is an issue of critical importance in the adolescent population. Research indicates that substance use is often initiated during the adolescent period and that brain reward areas are still undergoing changes during this time. Despite this, little research has investigated the effects of repeated drug use on the reward mechanisms of periadolescent animals. For this reason, the present study examined the effects of repeated ethanol (EtOH) administration on the responsiveness of the nucleus accumbens septi (NAcc) to either EtOH or saline challenge. The data indicate that repeated exposure to EtOH produces temporal shifts in the dopaminergic (DAergic) activity of the NAcc, with peak activity occurring earlier. Importantly, following repeated injections of EtOH, saline injections alone elicit DA increases in the NAcc suggesting that the context of alcohol administration produces fundamental changes in the way that neurochemical reinforcement mechanisms respond. The expectancy of the drug alone elicits reward-related activity within the NAcc.