Induction of true precocious puberty by neonatal treatment with danazol in female rats.

Female rats at 5 days of age were given a single subcutaneous injection of varying doses of danazol or vehicle. Rats treated with 300 micrograms of danazol showed significant (P < 0.01, respectively) advancement in the day of vaginal opening (37.50 +/- 0.49 days vs. 25.20 +/- 0.19 days; mean +/- S.E.M.), first estrus (38.19 +/- 0.62 days vs. 29.10 +/- 0.26 days) and onset of estrous cycle (49.63 +/- 1.30 days vs. 37.07 +/- 1.50 days). All rats treated with danazol showed 4- or 5-day estrous cycle in the adulthood. Rats treated with 300 micrograms of danazol at 5 days of age discharged luteinizing hormone in the late stage of first proestrus. These results demonstrate that neonatally administered danazol produces the true precocious puberty in female rats, and this sexual precocity rat represents a unique model for analysis of the onset of puberty.