UCSF

In many animals, the display of female sexual receptivity relies on internal states such as the hormonal status of the animal. Female mice, for example, are receptive toward males only peri-ovulation, presumably to maximize reproductive success. The sex hormone responsive neural circuits that regulate female receptivity remain largely unknown, but are likely sexually dimorphic since males do not become receptive under the same hormonal stimuli that induces ovulation and receptivity in females. Progesterone and the progesterone receptor (PR) are required for ovulation and female sexual receptivity. We have generated a genetically targeted PR reporter mouse to map a receptivity circuit. We find that PR is expressed in a sexually dimorphic pattern in many brain regions including a small pool of neurons in the ventromedial hypothalamus (VMH), a center required for receptive behavior. We find that PR-expressing neurons in the VMH send a female specific projection to the anteroventral periventricular nucleus (AVPV), a hypothalamic region that is critical for ovulation. These data suggest that a sexually dimorphic circuit mechanism coordinates ovulation and receptivity. With the genetic tools we have generated, we can now begin to probe the behavioral relevance of PR-expressing neurons.