Uterine peroxidase as a marker for estrogen action.

Abstract

Administration of a single dose of estradiol to immature rats gives rise to the appearance of substantial amounts of peroxidase (donor:hydrogen-peroxide oxidoreductase, EC 1.11.1.7) enzyme activity in the uterus. This enzyme induction, which is inhibited by administration of actinomycin D and cycloheximide, can be detected at 4 h after administration of estradiol, reaches a maximum level by 20 h, and thereafter declines. The amount of uterine peroxidase seen at 20 h after a single dose increases with dose from 0.1-100 .mu.g of estradiol. Estrone and estriol also show dose-dependent induction of peroxidase, and the quantitative peroxidase responses to these steroids follow their uterotropic capacities. The antiestrogen CI628, capable of low levels of enzyme induction by itself, can inhibit the induction due to estrogen. Solubilization of the uterine enzyme with divalent cations, especially Ca, results in a substantially increased yield of peroxidase. This extraction method provides an enzyme of about 50,000 MW in distinction to the large aggregated form obtained by the usual extraction with NaCl.