Prelimbic cortex to ventral tegmental area projection regulates early social isolation stress-potentiated heroin seeking in mice.

Early-life adversities increase vulnerability to substance use disorders, which are characterized by persistent, uncontrollable drive to seek drugs, often leading to relapse. Previously, we reported that early social isolation (ESI) during adolescence potentiates heroin-seeking in mice. However, the underlying neurobiology remains unknown. Here, we found that ESI aggravated heroin-induced neuronal dysfunction in prelimbic cortex (PrL) to ventral tegmental area (VTA) projecting neurons. Activating PrL->VTA projection attenuated ESI-potentiated heroin seeking, alongside normalized neuronal function. RNA-seq revealed that ESI and heroin convergently altered genes regulating morphogenesis and metabolism, with Tmsb4x (thymosin β4) as a key gene. ESI and heroin interaction affected genes regulating cell cycle and DNA damage response, with Mcm3 and Mcm7 (minichromosome maintenance proteins 3/7) as hubs. PrL thymosin β4 infusion or CRISPR-Cas9-mediated PrL->VTA projection-specific Mcm3/7 knockdown attenuated ESI-potentiated heroin-seeking and neuronal hypofunction. Our study suggests that ESI-potentiated heroin relapse is associated with neuronal and transcriptional alterations in PrL->VTA projection.