EFFECTS OF ESTRONE AND 16, 17-PYRAZOLEESTRONE ON ESTROGEN RECEPTOR OF RAT UTERUS

16,17-Pyrazoleestrone is a derivative of estrone. Experiments showed that the estrogenic activity of 16,17-pyrazoleestrone was weaker than that of estrone. When a series of doses were used, estrone simutaneously increased uterine weight and estrogen receptor concentration, while 16,17-pyrazoleestrone exhibited no significant influence on both parameters in rats. In in vitro studies, however, the affinity of these compounds for estrogen receptor was found to be very similar. Since estrogen was shown to have higher distribution in rat uterus, the conclusion was then made that the difference of uterine estrogen receptor concentration between the rats treated with estrone and 16,17-pyrazoleestrone may be attributed to the difference in distribution in uterus.