An epigenomic shift in amygdala marks the transition to maternal behaviors in alloparenting virgin female mice

In many species, adults care for young offspring that are not their own, a phenomenon called alloparenting. However, most nonparental adults must be sensitized by repeated or extended exposure to pups before robustly displaying of parental-like behaviors. To capture neurogenomic events underlying the transition to active parental caring behaviors, we analyzed brain gene expression and chromatin profiles of virgin female mice co-housed with mothers during pregnancy and after birth. After an initial display of antagonistic behaviors and a surge of defense-related gene expression, we observed a dramatic shift in the chromatin landscape specifically in amygdala of the pup-exposed virgin females, accompanied by a dampening of defense-related gene expression. This epigenetic shift coincided with hypothalamic expression of the oxytocin gene and the emergence of behaviors and gene expression patterns classically associated with maternal care. The results outline a neurogenomic program associated with dramatic behavioral changes and suggest molecular networks relevant to human postpartum mental health. Overall design: RNA-Seq was performed on 53 individual mouse brain samples, with 4-5 biological replicates per condition and ChIP-Seq was performed on 25 samples, with 2 biological replicate pools of 3 animals per condition. ChIP-seq input samples were generated by skipping immunoprecipitation and sequencing background DNA.