THE UTERINE GROWTH-STIMULATING ACTIVITIES OF 17α-ETHYNYL-17-HYDROXY-5(10)-ESTREN-3-ONE (NORETHYNODREL) AND 17α-ETHYNYL-19-NORTESTOSTERONE1

Abstract

Despite structural similarity and certain common biological properties, the uterine growth-stimulating activities of Norethynodrel and 17[alpha]-ethynyl-19-nortestosterone were entirely different when dose-response curves of uterine weight were compared. These differences obtained whether the material was administered parenterally or intragastrically. In this test Norethynodrel acted like an estrogen (i.e., it had a steep dose-response curve slope), whereas 17[alpha]-ethynyl-19-nortestosterone behaved like an impeded estrogen, a testoid or a progestin (shallow slope). 17[alpha]-Ethynyl-19-nortestosterone was an antagonist of both Norethynodrel and estrone, whereas, Norethynodrel had no effect on estrone-induced uterine growth. Again these relationships were qualitatively similar for intragastric and subcutaneous administration. Qualitatively each compound appeared to maintain its specific integrity regardless of route of administration.