Failure of testosterone propionate to induce the early-androgen syndrome in rats previously injected with progesterone

Since Barraclough (1961) suggested that sterility produced by treatment with androgens before puberty could depend on functional alterations of the hypothalamic regions responsible for the control of the cyclic ovulatory discharge ofgonadotrophin, many experiments have been made to determine the process by which the alteration is brought about. Recent work (Cagnoni, Fantini & Morace, 1964; Swanson & Van der Werff ten Bosch, 1964) has shown that the hypothalamic 'centres ' probably become sensitive to androgens only after the birth of the animal: the administration of large doses of androgens to pregnant rats has no effect on the function of the ovary in female offspring, although it has been demonstrated that the hormones in question pass rapidly through the placenta and reach the foetus unchanged. The failure of androgens to induce the 'early-androgen ' syndrome in such an ex-perimental situation could depend on the presence of steroid hormones of maternal origin. The effects of testosterone propionate (TP) administered to newborn female rats pretreated with varying doses of progesterone (P) were therefore studied. We used thirty-six female rats of the Wistar strain which were housed at constan