Early estrogen effects on newly synthesized RNA and phospholipid in subcellular fractions of rat uteri

Abstract

The in vivo incorporation of orthophosphate-P 32 into RNA of subcellular fractions of immature and ovariectomized rat uteri was stimulated within the first hour after estradiol-17β injection. Incorporation was considerably higher in the RNA of the nucleus than mitochondrial, microsomal, or soluble fractions with a 1 hour exposure to isotope. The effect of estrogen was similar in all subcellular fractions, indicating an effect on some common site of synthesis. An increased incorporation into lipid occurred within 2 hours and was again found in all subcellular fractions. When uteri were incubated in vitro with labeled precursors, the effect of in vivo estradiol pretreatment on RNA synthesis was lost. At the same time, estrogen-increased phospholipid synthesis was maintained.