This proposal investigates the implication of both genetic variation and epigenetic modification on HPA axis regulation and excessive alcohol consumption in primates. These studies will draw upon the rhesus macaque ethanol self-administration model, which will enable a longitudinal study design examining genomic DNA methylation before and after 12 months of ethanol consumption, accurate measure of ethanol intake and endocrine levels, and access to both blood and brain tissue samples for the comparison of epigenetic changes in both tissues. We will use whole-genome approaches to measure CpG methylation levels in the tissues before and after chronic ethanol consumption. We will test whether changes in methylation levels are associated with corresponding changes in gene expression. We will also test whether changes in methylation patterns in the blood parallel those found in the brain. Also taking advantage of the high efficiency of next generation sequencing technology, we will sequence neurotransmitter genes from the HPA axis and monoamine signaling pathways in a large cohort of animals. We will test the association between common variants and endocrine dysfunction, and will evaluate potential additive effects and interactions between risk alleles in multiple signaling pathways. We will also explore whether there is an association between specific alleles or haplotypes and changes in methylation following chronic alcohol consumption (allele-specific methylation). Together, these approaches will provide a comprehensive basis for evaluating the cumulative genetic vulnerabilities that contribute to excessive alcohol use. Owing to the close evolutionary relationship of non-human primates, these studies will have a high-degree of translational relevance to human alcoholism, potentially 1) identifying alcohol-linked epigenetic modification of genes, 2) determining the relevance of epigenetic modifications in a clinically accessible tissue (blood) to those in the brain and 3) suggesting novel targets for the future treatment of alcohol use disorders.