Complex chemosensory control of female reproductive behaviors

Olfaction exerts a profound influence on reproductive physiology and behavior in many animals, including rodents. Odors are recognized by sensory neurons residing in the main olfactory epithelium (MOE) and the vomeronasal organ (VNO) in mice and many other vertebrates. The relative contributions of the MOE and VNO in the display of female behaviors are not well understood. Mice null for Cnga2 or Trpc2 essentially lack odor-evoked activity in the MOE and VNO, respectively. Using females mutant for one or both of Cnga2 and Trpc2, we find that maternal care is differentially regulated by the MOE and VNO: retrieval of wandering pups requires the MOE and is regulated redundantly by the VNO whereas maternal aggression requires both sensory epithelia to be functional. Female sexual receptivity appears to be regulated by both the MOE and VNO. Trpc2 null females have previously been shown to display male-type mounting towards other males. Remarkably, we find that females double mutant for Cnga2 and Trpc2 continue to mount other males, indicating that the disinhibition of male-type sexual displays observed in Trpc2 null females does not require chemosensory input from a functional MOE. Taken together, our findings reveal a previously unappreciated complexity in the chemosensory control of reproductive behaviors in the female mouse.