MASCULINIZATION AND DEFEMINIZATION INDUCED IN FEMALE HAMSTERS BY NEONATAL TREATMENT WITH ESTRADIOL, RU-2858, AND NAFOXIDINE

Newborn female hamsters were treated with 0.1 or 1.0 ng of estradiol benzoate (EB), with 1.0 ng-2.0 μg of the synthetic estrogen RU-2858, or with 0.1 or 0.5 μg of the antiestrogen nafoxidine. When adult the animals were treated with EB and progesterone and tested for the display of lordosis and with testosterone propionate and tested for the display of mounting behavior. The EB doses used failed to alter sexual differentiation. RU-2858 masculinized and defeminized in a dose-dependent manner being most effective when given neonatally as two divided doses. Nafoxidine inhibited lordosis without enhancing mounting behavior. The findings support the hypothesis that estrogens may be involved in the normal sexual differentiation process. © 1979.