Abstract
Summary
Uterine response to estradiol in immature female mice is inhibited significantly by concurrent injection of estriol. Extent of inhibition is proportional to amount of estriol added. Impeding interaction occurs along the ascending segment of the estradiol dose-response curve and with higher doses as well. In no case does a combination of estrogens have a positive additive action. These conclusions are based on both wet and dry uterine weight observations. Day by day analysis shows that uterine weight gain of each 24 hour period during 3 day estradiol treatment is inhibited when estriol is given concurrently. These studies negate the possibilities that estriol-estradiol interaction is a masked-summation effect in which time of maximum effect has shifted, or that an additive effect occurs in which two estrogens combined exceed maximum response dose. Rather, it appears that estriol competes actively at a physiologic site essential in development of usual estradiol stimulation of the uterus.
Get full access to this article
View all access options for this article.