INDUCTION OF PHOSPHOINOSITIDE-MEDIATED SIGNAL-TRANSDUCTION PATHWAY BY17-BETA-ESTRADIOL IN RAT VAGINAL EPITHELIAL-CELLS

In the present study, the induction of the phosphoinositide signal tra nsduction pathway by 17 beta-oestradiol has been demonstrated in rat v aginal epithelial cells (VEC). We have shown an increase in the metabo lism of phosphoinositol lipids by H-3-myoinositol incorporation as wel l as production of inositol phosphate in VEC in vivo and in vitro foll owing oestradiol administration. Concomitant changes in intracellular calcium levels have also been observed under the influence of oestradi ol. To rule out the effects of cytokines, parallel studies were perfor med using primary cultures of VEC. Oestradiol-induced calcium uptake w as seen even in the presence of actinomycin D and cycloheximide which inhibit transcription and translation respectively. Calcium uptake was blocked by neomycin, an inhibitor of phosphoinositol lipid metabolism , and by the oestrogen receptor antagonist tamoxifen. Results suggest that oestradiol induces second messenger pathways in the VEC through s pecific receptors. Implications of these observations in cellular diff erentiation processes are discussed.