PROJECT SUMMARY Drug addiction is a massive public health concern that inflicts extensive burdens on our economy and society. The harmful consequences of drug abuse extend far beyond the addicts and gravely impact their families. A growing body of evidence suggests that the children of fathers who consumed drugs around the time of conception show altered brain function and behavioral abnormalities. We have established a highly translational paradigm of paternal opioid drug taking, using morphine self-administration in rats to study this phenomenon. Our results demonstrate that the male progeny of fathers (sires) that took morphine chronically are more susceptible to develop addiction-like traits and self-administer morphine. This multigenerational animal model offers a rare window into a pool of subjects that are more vulnerable to develop addiction, a population that has been historically difficult to identify. Here, we can reliably and systematically produce animals that show increased drug taking behavior, which offers a unique opportunity to delve into the mechanisms underlying addiction susceptibility. This multifaceted project will combine behavioral and molecular biological approaches to identify functionally relevant mechanisms that confer a higher propensity to develop addiction. The parent award and related studies address two major questions: (1) which germline epigenetic reprogramming events are critical for shaping development toward addiction vulnerability into adulthood? (2) what are the functionally relevant neuro-epigenetic processes that increase addiction-like behavior in our multigenerational model of drug taking? This supplement will support a NIDA summer intern who will be trained to develop research skills including data collection, data management, statistical analysis and dissemination (written and oral) or results.