Action of Progesterone and Synthetic Progestogens on Estrogen-Induced Ovarian Growth

Abstract

Summary

Five synthetic progestogens along with progesterone and 20a-hydroxy-pregn-4-en-3-one were compared for their ability to influence diethylstilbestrol (DES)-induced ovarian growth in the immature hypo-physectomized rat. Ovaries of DES-treated rats showed a marked increase in ovarian weight, total RNA, total DNA and the RNA/ DNA ratio. Norethindrone, norethindrone acetate, and medroxyprogesterone acetate inhibited DES-induced ovarian growth by preventing cell division as indicated by significant decreases in total DNA and RNA with no change in the ratio of RNA to DNA. Conversely, norethynodrel enhanced ovarian hyperplasia in DES-treated rats since total DNA and RNA were increased and the RNA/ DNA ratio remained unchanged. Progesterone, 20α-hydroxy-pregn-4-en-3-one, or 17α hydroxyprogesterone caproate did not alter DES-induced ovarian growth. Norethindrone was observed to have no effect on the uptake of ¹⁴C-DES by the ovary and therefore appears to antagonize the action of DES on ovarian growth rather than by blocking the incorporation of this estrogen by the ovary.