抄録
In Experiment 1, female rats were given a single subcutaneous injection of 1.25mg 5α-dihydrotestosterone (DHT) or its propionate (DHTP) on day 5 of postnatal life. All of them showed regular estrous cycles as adults like untreated control animals. At about 60 days of age, the rats were ovariectomized and given 7 daily injections of 2mg progesterone (P) plus 0.2μg estradio1-17β(ED). Uterine trauma applied on the 4th day of P-ED injections resulted in well developed deciduomata in all animals by the day after the last injection. This made a sharp contrast to the failure of female rats receiving testosterone propionate (TP) neonatally to give a positive response under similar experimental conditions (Takewaki and Ohta, 1974). The mean weight of traumatized horns was significantly larger in DHTP-treated rats (but not in DHT-treated rats) than in controls.
In Experiment 2, rats were ovariectomized on day 4 and given a dose of 1.25mg DHT or DHTP on day 5. Controis were ovariectomized on day 4 but not given any steroid on the next day. A series of 7 daily injections of 2mg P plus 0.2μg ED was started at about 60 days of age, after the animals had received 3 daily injections of 0.2μg ED or 30 daily injections of 0.1μg ED. Incidence of deciduomata following uterine traumatization was markedly lowered only in animals treated with DHTP neonatally and given 0.1μg ED for 30 days as adults, no significant differences being found in both incidence and size of deciduomata among the other groups.
It was suggested that the effects of neonatal steroid administration on uterine responsiveness in adulthood are specific to the steroid. The previous conclusion that persistent estrus in androgen-sterilized rats plays a part in the reduction of uterine responsiveness was confirmed. An exposure of rats to estrogen for a prolonged postpuberal period was without effect, unless the animals had received enough androgen neonatally.
