A prenatal source for defeminization of female rats is the maternal ovary

Sexual behavior in laboratory rats is influenced by a variety of factors in the perinatal environment. Male rats are masculinized and defeminized in response to circulating testosterone perinatally. Females undergo a process of feminization but in some cases are exposed to testosterone. Previous work has shown that during prenatal development female rats normally undergo a partial masculinization and defeminization of sexual behavior as reflected by altered responsiveness to gonadal hormones in adulthood. In the present study we investigated whether the maternal ovary influences adult females' responsiveness to gonadal hormones. Pregnant rats were ovariectomized on Day 10 of pregnancy and their offspring tested for sexual behavior in adulthood. Following ovariectomy pregnancies were maintained by administration of systemic progesterone. In addition the ovariectomized pregnant rats were given one of three daily treatments (Days 10-21): 0.2 microgram estradiol benzoate in sesame oil and 0.1 cc propylene glycol, 5 mg of the aromatase inhibitor 1,4,6-androstatriene-3,17-dione (ATD) in 0.1 cc propylene glycol, or 0.1 cc propylene glycol. A control group was generated from SHAM operated mothers given daily control injections of propylene glycol and sesame oil. Offspring were ovariectomized in adulthood and tested for display of feminine sexual behavior in response to estradiol benzoate and progesterone or estradiol benzoate alone. Masculine sexual behavior was measured in response to testosterone propionate (TP). Feminine sexual behavior was enhanced in offspring from ovariectomized mothers given only progesterone replacement during pregnancy. Offspring from mothers treated with ATD displayed the greatest elevations in feminine sexual behavior. Estradiol treatments of ovariectomized mothers prevented the increase in feminine potential seen in offspring in the other groups.(ABSTRACT TRUNCATED AT 250 WORDS)