smRNA and transcriptomic analysis of rat nucleus accumbens and sperm in F0 and F1 following heroin self-administration

Recent findings indicate that parental emotional perturbations, such as stress, traumatic experience and drug addiction, can cause disease predisposition in the offspring, possibly through modifications in epigenetic signatures of the germline. However, the mechanisms by which germline epigenetic signatures may alter in responsive to neuronal activities remain poorly understood. Here we show that paternal heroin reinforcement experience can cause high incentive response to heroin in F1 male offspring, which is contingent on paternal high motivation rather than high intake of heroin itself. Zygotic microinjection of sperm RNA from Her-SA fully recapitulated the high incentive response of naturally born offspring, indicating a causal role of alterations in sperm RNAome in transmission of high incentive motivation for heroin. By using smRNA-seq and correlation analysis, we identified consistent down-regulation of miR-19b in nucleus accumbens and sperm of Heroin F0. Restoring the down-regulation of miR-19b in sperm RNA or overexpression of miR-19b in F1 nucleus accumbens normalized the phenotype. We also identified correlated expression, and direct transfer of mature miR-19b from the nucleus accumbens to cauda epididymis sperm via brain-borne extracellular vesicles trafficking. Taken together, we identify miR-19b as a key messenger critically involved in the intergenerational transmission of high incentive response to heroin, and establish a possible route for brain-to-germline information flow to mediate the heritable transmission of paternal emotional perturbations.