In vitro effect of estrogens on the peroxidase activity of human endometrium.

The effect of estrogen on the induction of human endometrial peroxidase was studied in vitro. When 17 beta-estradiol was added to the incubation medium, endometrial peroxidase activity was markedly increased, and the highest enzymatic activities were reached at about 12 h of incubation. The ability of estrogen and related compounds to increase peroxidase activity at a concentration of 10(-7) M was 17 beta-estradiol greater than estrone greater than 17 alpha-ethynylestradiol greater than estriol = diethylstilbestrol. Mestranol, progesterone, and testosterone had almost no activity. The induction of peroxidase by 17 beta-estradiol was inhibited by actinomycin D or cycloheximide. This method may be useful for determining the direct estrogenic effect of compounds in human endometrium.