Functional and Epigenetic Consequences of Paternal Alcohol Exposure

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Project Summary/Abstract Alcohol use disorder (AUD) is a highly heritable disease affecting millions of people in the United States. Although the heritability of AUD has been estimated to be ~50%, genetic variants only account for less than 1% of the risk for developing AUD. Recent evidence suggests that epigenetic factors, which alter gene expression without affecting the underlying DNA sequence, may explain some of the missing heritability of AUD. The most well studied epigenetic mechanism is DNA methylation occurring at sites within the promoter regions of genes, and it is mostly, although not always, associated with gene repression. Human and preclinical studies report that alcohol can alter the DNA methylation profile in male germ cells. Work in mice has shown that these changes can be transmitted to first generation progeny and that paternal alcohol exposure affects offspring's alcohol drinking behaviors and behavioral sensitivity to alcohol. However, no study has examined the effects of paternal alcohol exposure on operant alcohol self-administration in offspring. Thus, the overall goal of the proposed project is to use Wistar rats to examine alcohol self-administration behaviors and alterations to DNA methylation levels in the offspring of alcohol-dependent males. To do this, male Wistar rats will be exposed to alcohol vapor over 6 weeks to induce alcohol dependence. After alcohol exposure, males will be left undisturbed for 8 weeks (one cycle of spermatogenesis in rats) and then mated with alcohol naïve females. Offspring from these mating pairs will be tested on self-administration behaviors and assessed for DNA methylation changes in adulthood. The first aim of the proposed project is to identify whether paternal alcohol exposure changes acquisition and maintenance of operant alcohol self-administration in male and female offspring. Additionally, the second aim will determine if DNA methylation levels are altered in the sperm of alcohol sires, and if these changes are maintained in brain and tissue of offspring. The results will further knowledge as to the long term consequences of paternal preconception alcohol exposure and may elucidate novel inherited behaviors and/or biomarkers that can be used to develop new, or refine existing, preventive and therapeutic strategies for AUD.