Mice display robust and stereotyped behaviors towards pups: virgin males typically attack pups, while virgin females and sexually experienced males display parental care. I show here that virgin males that are genetically impaired in vomeronasal sensing do not attack pups and are parental, suggesting a key role of the vomeronasal system in controlling male infanticide. In addition, we have identified putative vomeronasal receptors (or receptor groups) for the detection of pup odors, thus uncovering new tools for the molecular and genetic dissection of male infanticide. Further, we have uncovered galanin-expressing neurons in the medial preoptic area (MPOA) as key regulators of male and female parental behavior. Genetic ablation of MPOA galanin- neurons results in dramatic impairment of parental responses in both virgin females and sexually experienced males. In addition, optogenetic activation of these cells in virgin males suppresses infanticide and induces pup grooming. Thus, MPOA galanin-expressing neurons emerge as an essential node of regulation of innate behavior in the hypothalamus that orchestrates male and female parenting while opposing vomeronasal circuits underlying infanticide. Our results provide an entry point for the genetic and circuit-level dissection of mouse parental behavior and its modulation by social experience.
