Protracted abstinence from heroin, but not cocaine, is associated with profound medial prefrontal cortex synaptic bioenergetic remodeling and lasting neural hypofunction

Relapse following prolonged abstinence is a primary challenge in the treatment of opioid and cocaine use disorders, driven in part by enduring dysfunction of medial prefrontal cortex (mPFC) circuits that impair inhibitory control over drug-seeking. The molecular substrates underlying this dysfunction, and whether they differ across drug classes, remain unknown. Here, we performed label-free quantitative proteomics of mPFC synaptosomes isolated from rats after 30-day abstinence following intravenous heroin or cocaine self-administration to profile synaptic adaptations that may contribute to relapse vulnerability. Heroin abstinence induced extensive synaptic proteomic remodeling characterized by coordinated downregulation of mitochondrial proteins involved in oxidative phosphorylation, including pyruvate dehydrogenase complex subunits that regulate carbon entry into mitochondrial metabolism. Targeted metabolomic profiling of whole mPFC revealed accumulation of upstream glycolytic and pentose phosphate pathway intermediates, consistent with altered pyruvate utilization and mitochondrial oxidation. Several bioenergetic metabolites also correlated positively with the severity of escalation of heroin intake. Consistent with the bioenergetic remodeling observed during protracted heroin abstinence, whole-cell patch-clamp recordings from layer V mPFC pyramidal neurons revealed lasting suppression of intrinsic excitability and a decreased spontaneous excitatory synaptic activity. Cocaine abstinence, by contrast, produced limited changes in synaptic bioenergetics while inducing a distinct cytoskeletal remodeling signature. Overall, these findings identify synaptic bioenergetic remodeling as a previously underappreciated feature of prolonged heroin abstinence and reveal a marked divergence in the molecular adaptations induced by heroin versus cocaine within the mPFC. These results implicate mitochondrial bioenergetic pathways as therapeutic targets for reducing relapse vulnerability specifically associated with opioid use disorder.