INTERACTION OF MALE SENSORY CUES AND ESTRADIOL IN THE INDUCTION OF ESTRUS IN THE PRAIRIE VOLE

In the prairie vole, estrus and ovulation are induced by stimulation f rom a male, which also increases the female's gonadal weight and serum estradiol level. It is not known whether the induction of receptivity is dependent solely on an endogenous increase in circulating estradio l or an interaction of increased estradiol and male sensory stimulatio n. Using a dose response paradigm, we examined if a dose of estradiol within physiological range was sufficient to induce receptivity. We al so examined if extended male contact could induce receptivity in ovari ectomized females tested either without estradiol replacement or with a subthreshold dose of estradiol. We found that elevating blood levels of estradiol to those found during estrus was sufficient to induce se xual receptivity; male contact was not necessary. Extended male cohabi tation did induce estrus in ovariectomized females treated with a subt hreshold dose of estradiol, a dose which without male contact did not support sexual receptivity. In these same females, the extended male c ontact elevated circulating estradiol levels; the source of the estrad iol is unknown.