Dorsal raphe oxytocin receptors regulate the neurobehavioral consequences of social touch

Prosocial interactions are essential for group-living animals and are regulated by tactile cues shared among the group members. Neurobiological mechanisms through which social touch influences prosociality and related affective behaviors are relatively unknown. Using the evolutionarily ancient mother-young dyad as a model, we hypothesized that neurobehavioral consequences of social touch involves an interaction between central oxytocin (released during social touch) and serotonin (regulating affect and neuroplasticity). New mother rats showed upregulation of numerous aspects of the oxytocin system in the midbrain dorsal raphe (DR; source of forebrain serotonin) compared to non-maternal females. Preventing this upregulation by OTR knockdown in the maternal DR elicited infanticide, reduced nursing, increased aggression, and decreased active coping behavior. OTR knockdown also decreased serotonin-immunoreactive fibers, and increased neuroplasticity-restricting perineuronal nets, in the primary somatosensory cortex. Thus, oxytocin signaling in the DR regulates mechanisms involved in serotonin-induced cortical plasticity, which refines the tactile processing underlying prosocial behaviors.