Sex Steroids in Reproductive Tract Tissues: Regulation of Estradiol Concentrations by Progesterone1

Abstract

Estradiol-17.beta. (E2) and progesterone (P) were quantified in the reproductive tract tissues and striated muscle of rhesus monkeys and rats. After homogenates of these tissues were extracted with ether and defatted, E2 and P were isolated by chromatography on Sephadex LH-20 columns and quantified by radiommunoassay. Rhesus monkeys treated with E2 had significant elevations of this steriod in the reproductive tract tissues (oviduct and uterus) but not in skeletal muscle. When monkeys were treated with a combination of P and E2 the amount of E2 in the reproductive tract of this species was significantly reduced. Similar results were obtained in rats, i.e., after combined P and E2 treatment, the tissue levels of E2 were significantly lower than those in the uteri of animals not given P. P levels were significantly higher in skeletal muscle of rats treated with E2 + P. E2 treatment alone increased the amount of endogenous P found in the rat uterus.