Androgenic influences on feminine sexual behavior in male and female rats: defeminization blocked by prenatal antiandrogen treatment.

The prenatal influence of androgen on the development of female sexual behavior in rats was investigated. The nonsteroidal antiandrogen, flutamide (4'-nitro-3'-trifluoromethylisobutyrylanilide; SCH), was administered to pregnant female rats from days 10--22 of gestation in dosages of either 1 mg/mother-day or 5 mg/mother-day. Males and females were gonadectomized in adulthood and tested for the display of lordosis in response to estradiol benzoate (EB) alone or EB with progesterone (P). Males exposed prenatally to either the 1- or 5-mg dosage of flutamide exhibited significantly higher lordosis quotients than controls when given EB alone. The addition of P was without effect in all male groups with regard to estrogen-induced lordosis. Females exposed prenatally to flutamide had significantly higher lordosis quotients than controls when given either 0.175 or 0.25 micrograms EB daily for 3 days. Addition of P to EB treatment significantly facilitated lordosis display in control and flutamide-treated females. The increase of feminine sexual behavior in both males and females of feminine sexual behavior in both males and females resulting from prenatal antiandrogen treatment suggests that androgen, prenatally, inhibits development of female sexual behavior. This androgenic inhibition of sexual receptivity (defeminization) seems to be related to the animal's sensitivity to estrogen in adulthood.