Estrogen Stimulation of Phosphatidylinositol Metabolism in Mouse Uterine Tissue

The effect of estrogens on incorporation of labeled precursor into inositol-containing phospholipids (PI) from ovariectomized mouse uterus was investigated. The results indicate that diethylstilbestrol (DES) a potent mitogen, stimulated incorporation of myo-[3H]inositol into uterine PI in 1-3 h, with maximal incorporation occurring at 6 h. This activity followed a dose-dependent increase, with a maximal effect at 5 micrograms/kg. Incorporation of radiolabeled phosphorous into the polyphosphoinositides was also increased in estrogen-stimulated uterine tissue. Studies using a weak uterotropic DES derivative, Z,Z-dienestrol, produced an early stimulation of the PI response comparable to DES. This activity was increased by Z,Z-dienestrol, with minimal estrogen receptor occupancy, and did not result in stimulation of DNA synthesis. These findings would suggest that uterine PI stimulation may not occur via an estrogen receptor-mediated mechanism related to tissue proliferation induced by estrogens.