In Vitro Inactivation of Three Naturally Occurring Estrogens by Liver From Fetal, Newborn, Day-Old and Adult Rats

Abstract

In vitro incubation of estrogens with liver from adult or day-old rats decreased the uterotrophic activity of estrone and estradiol-17ß more than did liver from newborn or fetal rats. The action of liver preparations on estradiol-17α was minimal. The microsomes from fetal liver were shown to be deficient in their ability to inactivate estradiol-17ß. The estrogen inactivating system of fetal liver, particularly the microsomal fraction, was less effective than that of adult liver. The marked increase in potency which occurred during the first 24 hours after birth may well have been due to partial maturation of this microsomal system.