Effect of superfusion with human male serum, bovine serum albumin or non radioactive estrogens on the retention of tritiated estradiol-17β and estriol by the rat uterus

Abstract

Slices of mature rat uterus were superfused with either tritiated estradiol-17β or estriol, and subsequently superfused with different washing solutions. The retention of the labeled steroids by the nuclei of glandular and deep stromal cells and by the eosinophils was studied using a dry radioautographic technique for soluble compounds. Superfusion with a washing solution containg non-radioactive estradiol-17β partially displaces either tritiated estradiol-17β or estriol from the nuclei of uterine cells. Superfusion with a washing solution containing either human male serum, bovine serum albumin, or non-radioactive estradiol-17β or estriol partially extracts tritiated estradiol-17β from the uterine eosinophils. Superfusion with a washing solution containing either non-radioactive estradiol-17β or estriol partially displaces tritiated estriol from the uterine eosinophils. Non-radioactive estradiol-17β displaces more label from the nuclei of uterine cells than does non-radioactive estriol, especially when the tracer used is tritiated estriol. On the contrary, nonradioactive estriol displaces more radioactivity from the eosinophils than does non-radioactive estradiol-17β, especially when the tracer is tritiated estradiol-17β. These results suggest that there is some exchange of receptor-bound estrogens with exogenous estrogens for both the cytosol-nuclear and the eosinophil binding systems, and that the cytosol-nuclear and the eosinophil binding systems differ in regard to their retention of estradiol-17β and estriol.