Persistent transcriptional eventsamples were incubated on ice for 30 min and then centrifugeds in ventral tegmental area (VTA) and other reward relevant brain regions contribute to enduring behavioral adaptations that characterize substance use disorder (SUD). Recent data from our laboratory indicate that aberrant accumulation of the newly discovered histone post-translational modification (PTM), H3 dopaminylation at glutamine 5 (H3Q5dop), contributes significantly to cocaine-seeking behavior following prolonged periods of abstinence. It remained unclear, however, whether this modification is important for relapse vulnerability in the context of other drugs of abuse, such as opioids. Here, we showed that H3Q5dop plays a critical role in heroin-mediated transcriptional plasticity in midbrain. In rats undergoing abstinence from heroin self-administration (SA), we found acute and persistent accumulation of H3Q5dop in VTA. By attenuating H3Q5dop during abstinence, we both altered gene expression programs associated with heroin withdrawal and reduced heroin-primed reinstatement behavior. These findings thus establish an essential role for H3Q5dop, and its downstream transcriptional consequences, in opioid-induced plasticity in VTA.SIGNIFICANCE STATEMENT Opioid addiction is a chronically relapsing disorder defined by pathological drug-seeking behavior. Persistent relapse vulnerability is hypothesized to reflect a functional “rewiring” of reward-processing circuitry in the brain. This phenomenon is precipitated by drug-induced alterations in transcriptional plasticity of midbrain dopamine neurons, indicating an important role for epigenetic regulatory mechanisms in opioid dependence. We found that the newly discovered histone modification, H3 dopaminylation at glutamine 5 (H3Q5dop), was increased in ventral tegmental area (VTA) during periods of abstinence. H3Q5dop accumulation was found to regulate transcriptional programs associated with chronic heroin exposure. Using viral-mediated gene therapy to reduce H3Q5dop accumulation during abstinence resulted in attenuated heroin-primed seeking behaviors. Together, our results indicate that H3Q5dop plays an abstinence-specific role in regulating heroin-induced behavioral plasticity during prolonged abstinence.Competing Interest StatementThe authors have declared no competing interest.