Adolescence is a period of development that is associated with increased risk taking behaviors and experimenting with drugs of abuse, including alcohol and nicotine. Early onset of use of these agents may be associated with long-term changes in behavior and enhanced sensitivity to the subsequent effects of alcohol in adulthood. The present experiment was designed to assess the long-term behavioral alterations that occur due to adolescent exposure to ethanol and nicotine, either alone or in combination, on adulthood responsivity to the rewarding properties of environmental cues paired with ethanol. It was hypothesized that adolescent rats exposed to the combination of ethanol and nicotine would exhibit enhanced novelty seeking behaviors in adulthood. When assessing the rewarding properties of environmental cues paired with ethanol in adulthood using the CPP paradigm, it was hypothesized that adolescent rats exposed to the combination of a moderate dose of alcohol (0.75 g/kg) and nicotine (0.4 mg/kg) would more readily acquire a CPP in adulthood as compared to animals exposed to either drug alone. However, no changes in novelty seeking behaviors or conditioned place preference in adulthood were observed due to exposure to ethanol and/or nicotine during adolescence .Methodological considerations are discussed. Currently, other experiments are being conducted to assess the effects of nicotine on voluntary ethanol treatment in adolescent and adult male rats.

During adolescent brain maturation, there are likely sensitive periods where environmental conditions, including drug exposure, may influence development by modifying neuronal connections. Altering neuronal function may produce different phenotypes than expected under normal conditions that may influence subsequent responding to drugs of abuse after the brain is fully mature. Experiment one investigated the relationship between novelty preference and cocaine place preference in adolescent and adult rats. High responding adolescent rats displaying greater free choice novelty exploration (but not forced novelty locomotion) expressed decreased cocaine place conditioning compared to low responding rats. No relationship was found in adult rats. Experiment two evaluated novelty-induced behaviors in adulthood after adolescent cocaine exposure. Repeated cocaine administration produced greater stress and anxiogenic behavioral responses to novelty in adult rats. Repeated alcohol administration produced less-inhibited novelty-induced behaviors in adulthood. Experiment three and four evaluated the consequence of developmental cocaine exposure on the rewarding efficacy of cocaine in adolescence and adulthood. Additionally, the interaction of D2 receptors and the rewarding efficacy of cocaine were investigated. After developmental cocaine exposure, adolescent and adult rats demonstrate decreased rewarding efficacy to cocaine. Importantly, blockade of the D2 receptor prevents cocaine-induced neurochemical changes, potentially regulating the behavioral and neurochemical alterations that occur after repeated drug use that increases the likelihood of dependence. Together, these data implicate both short and long-term behavioral adaptations that occur after developmental cocaine exposure that may result in a predisposition to develop adulthood drug dependence.