Sexual preference and feminine and masculine sexual behavior of male rats prenatally exposed to antiandrogen or antiestrogen.

Male rats were prenatally (Day 10-19 of pregnancy) exposed to an antiestrogen, nitromifene citrate (CI628, 1 mg/rat), or an antiandrogen, cyproterone acetate (CA, 10 mg/rat), and in adulthood were examined for their exhibition of male-typical and female-typical behavior pattern. Treatment with CI628 abolished the capacity of the adult intact male to ejaculate, enhanced his potential to exhibit feminine sexual behavior, and decreased the intensity of the level of female-oriented behavior in a two-choice stimulus situation (estrous female vs active male). The administration of testosterone (T) did not alter these behaviors. Males exposed to CA showed low levels of lordosis behavior and normal levels of female-oriented preference. Further, they showed increased frequency of mounts and decreased number of intromissions, and only a few males ever ejaculated. Macroscopic inspection of the genital organs of the CI628-treated males revealed complete absence of the prostate. The dissections of the CA-treated males revealed a poorly developed penis and a blind-ending vagina. It was concluded that prenatal estrogen (E) is involved (1) in determining the development of mechanisms destined to mediate the display of male-typical behaviors in adulthood, (2) in suppressing the development of mechanisms of female-typical behaviors, and (3) seems to stimulate neural mechanisms influencing sexual preference behavior in the adult.