Epigenetic regulation of aggression-linked genes following prenatal stress enhances risk for sexual aggression in male rat offspring

Early-life psychosocial adversity can shape adult behaviour through enduring epigenetic mechanisms, yet the neurobiological pathways linking parental stress to offspring socio-affective behaviour remain incompletely understood. Here, we investigated whether paternal social isolation and maternal prenatal stress are associated with persistent DNA methylation differences in aggression- and stress-related neurochemical receptor genes in male rat offspring, and whether these molecular alterations co-occur with changes in aggression-like and maladaptive mating behaviour. Male Wistar rats were generated from F0 males housed either in groups or in social isolation and from dams exposed to prenatal restraint stress or control conditions. In adulthood, male offspring were assessed for aggression-like behaviour using the resident-intruder test and for maladaptive mating attempts toward non-receptive females using the Sexual Aggression Test, a rodent paradigm capturing forced or inappropriate mating behaviour. Targeted DNA methylation profiling of the androgen receptor, corticotropin-releasing hormone receptor 1, oxytocin receptor, and serotonin receptor 1A genes was performed using pyrosequencing in the amygdala, hippocampus, hypothalamus, and prefrontal cortex. Paternal social isolation was associated with increased methylation of stress- and androgen-related genes in limbic and prefrontal regions, whereas prenatal stress was linked to region-specific alterations in oxytocinergic and serotonergic gene methylation. These epigenetic patterns co-occurred with heightened aggression-like behaviour and increased maladaptive mating attempts in offspring from stress-exposed lineages. Despite modest methylation effects and model limitations, the findings suggest paternal and prenatal stress jointly shape offspring socio-affective behaviour through region-specific epigenetic variation.