Epigenetic function during heroin self-administration controls future relapse-like behaviors in a cell type-specific manner

Opioid abuse produces enduring associations between the drug euphoria and features of the drug-taking experience, and these powerful associations can trigger relapse in individuals recovering from opioid use disorder. We show here that the epigenetic enzyme, histone deacetylase 5 (HDAC5), functions in the nucleus accumbens (NAc) during active heroin use to limit future relapse-like behavior. Moreover, enhancing HDAC5 function in NAc dramatically suppresses context-associated and reinstated heroin seeking behaviors, but it does not impact sucrose seeking. We also find that HDAC5 functions within dopamine D1 receptor-expressing medium spiny neurons (MSNs) to suppress cue-induced heroin seeking, but within dopamine D2 receptor-expressing MSNs to suppress drug-primed heroin seeking. Using cell type-specific transcriptomics analysis, we found that HDAC5 reduces expression of numerous genes linked to ion transport, and it decreases intrinsic excitability of NAc MSNs, suggesting that HDAC5 limits relapse vulnerability by suppressing NAc MSN firing rates during active heroin use. We used microarrays to define genes differentially expressed in the presence or absence of AAV2-DIO-HDAC5-3SA in both D1 and D2 cell-types derived from Nucleus accumbens following vTRAP. Testing the transcriptomic effects of overexpressing a nuclear form of HDAC5 in the nucleus accumbens selectively in medium spiny neurons that expressed either dopamine receptor D1R or D2R.