Project description:Familial transmission and high heritability of liability for drug abuse has been demonstrated by large scale epidemiological and twin studies, but the role of pre-existing susceptibility to addiction is still not clear. Our data show that F1 and F2 offspring sired by rats with high motivation for drug reinforcement and drug intake during cocaine self-administration maintained their ancestor’s addict-like behavior. This paternal transmission of drug addiction is an acquired trait that is dependent on cocaine induced high motivation in F0. Reduced representation bisulfite sequencing of F0 and F1 sperm DNA reveal a few persistent epigenetic changes in genes that critically regulate early development and morphogenesis. These epigenetic traits may underlie alterations in the neurological basis that lead to the transmission of cocaine motivation. Our results reveal the epigenetic transgenerational inheritance of drug craving and provide a potential etiology in cocaine abuse vulnerability.
Project description:Vulnerability to relapse during periods of attempted abstinence from cocaine use is hypothesized to result from rewiring of brain reward circuitries, particularly ventral tegmental area (VTA) dopamine neurons. How cocaine exposures act on midbrain dopamine neurons to precipitate addiction-relevant changes in gene expression is unclear. We found that histone H3 glutamine 5 dopaminylation (H3Q5dop) plays a critical role in cocaine-induced transcriptional plasticity in midbrain. Rats undergoing withdrawal from cocaine showed an accumulation of H3Q5dop in VTA. By reducing H3Q5dop in VTA during withdrawal, we reversed cocaine-mediated gene expression changes, attenuated cue-induced dopamine release in nucleus accumbens and reduced cocaine-seeking behavior. These findings establish a neurotransmission-independent role for nuclear dopamine in relapse-related transcriptional plasticity in VTA.
Project description:<p>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.</p> <p>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.</p>