THE EFFECT OF VARIOUS ESTROGENS ON THE WEIGHT, CATECHOLAMINE CONTENT AND RATE OF CONTRACTIONS OF RAT UTERI

¹ Department of Pharmacology, University of Minnesota Medical School, Minneapolis, Minnesota

Dose-response relationships of the estrogens were determined on ovariectomized rats and their relative potencies were calculated. With respect to uterine weight, the relative potencies were estradiol-l7 (1.0), diethylstilbestrol (0.32), estrone (0.091), estradiol-17 (0.018) and estriol (0.0042). The relative potencies for increasing the epinephrine content per uterus were estradiol-17 (1.0), diethylstilbestrol (0.42), estrone (0.33), estradiol-l7 (0.14) and estriol (0.11). Estriol produced a significant elevation of epinephrine but, unlike the other estrogens, did not cause further increases with higher doses. With the exception of estriol, there was a correlation between uterine weight and epinephrine content per uterus after administration of the various estrogens. Similar changes were not observed for norepinephrine. The rate of uterine contraction in vitro was inversely proportional to the epinephrine content per uterus.