The Impact of Male Social Status on Vaginal Secretory Responses in Mice

We have recently described a murine model of vaginal secretion that allows the measurement of minute changes in vaginal secretion. Using this model, we determined that female mice experience a vaginal secretory response to the scent of males, a response regulated by circadian and estrous factors since females did not respond during their sleep phase, nor when in metestrus. Female mice can distinguish the social status of a male by scent cues and show a preference for the scent of dominant males. We therefore tested whether or not vaginal responses to male scent differ by the social status of that male. Vaginal secretory responses were measured using a recently described method employing a colorimetric thread. In addition, while we have shown that the proposed female attractant α/β farnesenes evoked a strong vaginal response in female mice, a second volatile preputial gland-derived messenger, 1-hexadecanol, has also been proposed to serve as a female attractant. Here we test whether or not 1-hexadecanol similarly stimulates a vaginal secretory response. We now report that the female vaginal secretory response differs according to the social status of the male: the urine-borne scent of dominant males elicited a vaginal response, while samples from non-dominant males did not. In related odor-preference tests we confirmed that female mice spend more time investigating the urine scent of dominant males. We additionally tested whether or not a second putative female attractant 1-hexadecanol would elicit a vaginal secretory response. Like the α/β farnesenes, 1-hexadecanol is volatile, derived from preputial glands, and induces an investigatory response in females. However female mice did not experience a vaginal secretory response to the scent of 1-hexadecanol. We did confirm that females spent more time investigating hexadecanol over vehicle, indicating that there can be a disconnect between behavioral measures of interest and a vaginal preparatory response. In summary, we find that subordinate male mice do not elicit a vaginal secretory response, indicating that male social status impacts the physiological responses of females to the prospect of coitus. We additionally find that in contrast to farnesenes, the putative female attractant 1-hexadecanol does not elicit a vaginal response. These findings underscore the potential value of this murine model and indicate that even in mice, vaginal responses are under complex regulation.