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Epigenetics of Cocaine and Nicotine Addiction

This project characterizes DNA methylation and gene expression changes that occur in the human brain, specifically in neurons from the rostral striatum. Major advances from NIDA funded initiatives for noninvasive neuroimaging studies have made it possible to study neuroanatomical, neurochemical and functional changes in the human brain that contribute to the vulnerability to abuse drugs, together with the neurotoxic consequences of years of drug misuse. Animal models have been developed to explain the fundamental behavioral and biological mechanisms of addiction, including reward, tolerance and dependence. From these studies, we learned that cocaine abuse not only alters the epigenetic status of genes, but also induces particular epigenetic modifications depending on the frequency of the drug's administration. Certain genes are switched on by infrequent (short-term exposure) administration, while others are switched on only after chronic administration (addiction/dependence). Animal studies have also suggested that cocaine-seeking habits modeling chronic cocaine addiction in humans depend upon dopamine-dependent serial connectivity linking the ventral (nucleus accumbens) with the dorsal striatum (caudate nucleus). The primary goal of this study is to identify DNA methylation and gene expression changes that occur in the transition from recreational cocaine use to cocaine addiction. High throughput sequencing studies were designed to investigate unique postmortem human brain specimens from individuals that met criteria for cocaine dependence, as compared to unaffected age-matched controls.

Brain biospecimens were available from the University of Miami Brain Endowment BankTM, from a collection of phenotypically well-characterized postmortem tissues sampled from chronic cocaine abusers that came to autopsy. This biobank of postmortem brain specimens and annotated genomic data serve as a research resource to support NIDA's scientific mission.