Dependence Driven Alterations in Ethanol Reinforcement

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DESCRIPTION (provided by applicant): This INIA Consortium U01 Project is focused on genetic differences and neuroadaptations in brain circuitry that are responsible for individual differences in vulnerability to excessive consumption of alcohol. We will extend our previous findings using an intragastric consumption (IGC) model in which several days of passive exposure to ethanol (or water) via a chronic intragastric (IG) cannula are followed by a self-infusion test procedure in which voluntary ingestion of a flavored solution is paired with IG ethanol. Previously, we found that IGC and preference for the ethanol-paired flavor (compared to a water-paired flavor) is enhanced by passive ethanol exposure and varies as a function of genotype in both rats and mice. We now propose to focus primarily on mice. Aim 1 will examine key parameters of the passive infusion phase in two inbred strains, C57BL/6J and DBA/2J. These parameters include: (a) dose per infusion and total daily dose, (b) number of daily ethanol infusions, and (c) number of days of passive ethanol exposure. Aim 2 will further address the hypothesis of genetic differences in sensitivity to dependence-driven ethanol reinforcement by extending the model to characterize IGC in 15 standard inbred strains, allowing examination of genetic correlations between IGC and a wide range of previously studied ethanol phenotypes. With support from the INIA Colorado Gene Array Core, we will also examine genetic correlations with whole brain gene expression. Aim 3 will test whether passive IG ethanol exposure produces changes in ethanol reinforcement/reward using the conditioned place preference procedure and limited access operant self-administration. Aim 4 will involve collaboration with other INIA projects by testing two mouse models that have been selectively bred for high blood ethanol concentrations in binge drinking procedures: (a) the SHAG and SLAC lines, and (b) the HDID line and its genetic control (HS/Npt). Finally, with support from the INIA Neurocircuitry Mapping and Genotyping Core, Aim 5 will use c-Fos immunohistochemistry and lesions to identify specific brain areas that influence the enhancement in IGC after passive ethanol exposure. The long-term goal of this project is to understand the genetic and neurobiological processes underlying the excessive drinking that contributes to alcoholism in humans. By improving our understanding of these processes, we can identify more effective treatment and prevention strategies.