The Reinforcing Properties and Neurochemical Response of Ethanol

Alcohol drinking during adolescence is associated in adulthood with increased alcohol drinking and rate of alcohol dependence. Research examining the biological consequence of adolescent ethanol (EtOH) consumption on the response to EtOH in the neurocircuitry shown to regulate drug reinforcement is limited. The experiments were designed to determine the effects of peri-adolescent alcohol drinking on the reinforcing properties of EtOH within the posterior ventral tegmental area (pVTA) and the ability of EtOH microinjected into the pVTA to stimulate dopamine release in the nucleus accumbens shell (AcbSh). EtOH access (24-hour free-choice) by alcohol-preferring (P) rats occurred during post-natal day (PND) 30-60. Animals were tested for response to EtOH after PND 85. Intracranial self-administration techniques were performed to assess EtOH self-infusion into the pVTA. In the second experiment, rats received microinjections of EtOH into the pVTA and dialysis samples were collected from the AcbSh. The results indicate that in rats that consumed EtOH during adolescence the pVTA was more sensitive to the reinforcing effects of EtOH (lower concentration of EtOH supported self-administration) and the ability of EtOH microinjected into the pVTA to stimulate DA release in the AcbSh was enhanced (sensitivity and magnitude). The data indicate that EtOH consumption during adolescence altered the mesolimbic DA system to be more sensitive and responsive to EtOH. This increase in the response to EtOH within the mesolimbic DA during adulthood could be part of biological sequelae that are the basis for the deleterious effects of adolescent alcohol consumption on the rate of alcoholism during adulthood.