Influence of sex steroids on the production of prostaglandins F-2 alpha and E(2) and response to oxytocin in cultured epithelial and stromal cells of the bovine endometrium

The uterus is a primary target for sex steroid action in vivo during the estrous cycle and pregnancy. Cell cultures have been used to determine the specific function of the different cell types forming the uterus. We used endometrial cell cultures previously characterized in our laboratory to study the effect of estradiol (E) and progesterone (P-4) on prostaglandin (PG) production and on regulation of the response of the cells to oxytocin (OT). The studies were performed on confluent cultures of epithelial cells grown as a monolayer either on plastic or on filter inserts to allow basal-apical polarization. As described previously, prostaglandin F-2 alpha (PGF(2 alpha)) production was greater (3.7-fold, p < 0.0001) than prostaglandin E(2) (PGE(2)) production in epithelial cells, and the opposite was true in stromal cells (PGE(2) 9.9-fold > PGF(2 alpha), p < 0.0001). In epithelial cells, the basal production of PGE(2) (-61.6%, p < 0.0001) and PGF(2 alpha) (-51.7%, p < 0.0001) was reduced significantly by E and increased significantly by P-4 (PGE(2 alpha) +30.0% [p < 0.002]; PGF(2 alpha), +22.2% [p < 0.006]). No significant effect of sex steroids on the basal production of PGs was detected in stromal cells. OT stimulated the production of PGF(2 alpha) (6.7-fold, p < 0.0001) and PGE(2) (9.1-fold, p < 0.0001) in epithelial but not stromal cells. Treatment of the cells with E significantly (p < 0.001) increased OT-stimulated PGF(2 alpha) production in both the epithelial and stromal cells and that of PGE(2) in epithelial cells only. The effect of steroids and OT was similar in polarized (filter) and nonpolarized (plastic) epithelial cells. Analysis of the vectorial secretion of PGs in epithelial cells grown on filter inserts revealed that PGF(2 alpha) is preferentially secreted in the basal (p < 0.001) compared to the apical compartment. The direction of secretion was not influenced by steroid or OT treatments. The results suggest that epithelial cells of the endometrium are a preferred target for the regulation of PG synthesis by sex steroids and OT.