Early Estrogen Effects on Lipid Metabolism in the Rat Uterus1

The effects of short periods (1-4hr) of in vivo 17P-estradiol treatment on the subsequent in vitro incorporation of several isotopic precursors into rat uterine lipids were studied. Throughout this period, estrogen progressively accelerated 2-14C-acetate incorporation into all major lipid fractions examined. When phospholipids were doubly labeled with 2-14C-acetate and 32Porthophosphate, estrogenic stimulation of 32P incorporation occurred at a different and greater rate than 14C incorporation. Subsequent separation and identification of major uterine phospholipid classes allowed the finding that novel or selective differential synthesis of specific lipid classes did not occur; rather there was a similar and coordinate increase in the labeling of all classes. To elucidate the mechanisms involved in these responses, the synthesis of the largest class of uterine phospholipids was examined in detail. 90- min periods of estrogen treatment increased Me- 3H-choline incorporation into choline phospholipids by 70...