Paternal heroin self-administration in rats increases drug-seeking behavior in male offspring via miR-19b downregulation in the nucleus accumbens

Accumulating evidence indicates that drug addiction may lead to adaptive behavioral changes in offspring, potentially due to epigenetic modifications in parental germline. However, the underlying mechanisms remain inadequately understood. In this study, we show that paternal heroin self-administration (SA) increased heroin-seeking behavior in the F1 generation, when compared with offspring sired by yoke-infused control males, indicating cross-generational impact of paternal voluntary heroin seeking behavior. Notably, the increase of heroin seeking behavior in offspring was replicated by zygotic microinjection of sperm RNAs derived from sperm of heroin-SA-experienced rats. Analysis of non-coding RNAs in spermatozoa revealed coordinated changes in miRNA content between the nucleus accumbens and spermatozoa. We validated that restoration of miR-19b downregulation in sperm RNA from self-administration-experienced rats, in parallel with its overexpression in the nucleus accumbens of F1 offspring sired by heroin-SA-experienced fathers, reversed the increased heroin SA observed in these F1 offspring. Taken together, our findings suggest in rats that paternal heroin self-administration induces epigenetic changes in both brain and sperm miRNA, with miR-19b downregulation playing a critical role in mediating the epigenetic inheritance of increased heroin self-administration behavior in the F1 generation.