A prolactin-receptive neural circuit drives maternal interactions with pups in mice

The medial preoptic area (MPOA) of the hypothalamus drives the expression of maternal behaviors. Although prolactin action in the MPOA is essential for the onset of postpartum maternal behavior, it is still unknown how prolactin acts on underlying neural circuitry to modulate different aspects of maternal behavior. Here, we have identified a prolactin-receptive projection from the MPOA to the ventral tegmental area (VTA) that is specifically activated during interactions with pups. Activation of this prolactin-receptive MPOA-VTA projection stimulated increased maternal interactions with pups in virgin female mice, and the removal of prolactin action within this projection prevented the postpartum increase in maternal-pup interactions. Prolactin-receptive MPOA-VTA neurons modulate dopamine release into the nucleus accumbens (NAc), with stimulation of this projecting inducing dopamine release and increased pup interactions and inhibition blocking pup-induced dopamine release into the NAc. These data define a prolactin-receptive neural circuit that engages with reward pathways to drive increased motivation in mothers to interact with newborn offspring.