Effect of estrogen-treated porcine ampulla oviductal epithelial cells on early embryonic development in vitro and characterization of their protein synthetic activity

Recent studies by Buhi et al. have demonstrated that estrogen (E2) is responsible for the induction of de novo synthesis and secretion of certain oviductal secretory proteins (OSP) and inhibition of other OSP in porcine oviductal explant cultures. The present work was undertaken to evaluate the effect of E2-treated oviductal epithelial cell coculture on the development of early porcine embryos derived from in vitro matured and fertilized oocytes. In vitro synthesis of secretory proteins by E2-treated oviductal cells used for coculture was also investigated by one-dimensional (1D) and two-dimensional (2D) sodium dodecyl sulfate (SDS) polyacrylamide gel electrophoresis (PAGE). The results showed that the cleavage rate was significantly enhanced by coculturing fertilized eggs with E2-treated oviductal epithelial cells. The in vitro protein synthetic pattern of oviductal secretory proteins was influenced by E2 treatment. These variations included the disappearance of one protein (82 000 Mr) and the appearance of another (33 000 Mr) in the E2-treated group as assessed by 1D-SDS-PAGE. Additional proteins of Mr 97 000 and an Mr 36 000–45 000 complex were increased in abundance by the E2 treatment. Analyses by 2D-SDS-PAGE revealed three major E2-dependent proteins, of Mr 45 000 (pI 5.5), 43 000 (pI 5.5) and a 36 000–45 000 Mr (pI 4.8) protein complex, whereas polypeptides of Mr 97 000 (pI 5.1), 36 000 (pI 8.0) and 25 000 (pI 6.8) were inhibited by E2 treatment. The results demonstrated that porcine epithelial cell protein synthetic patterns are influenced by E2 treatment and that estradiol treatment of oviductal cells may increase the rate of zygote cleavage during early development in vitro in pigs.