Effects of estradiol and progesterone on secretion of epidermal growth factor and insulin-like growth factor-1 in cultured yak endometrial epithelial cells

We isolated and purified yak (Bos grunniens) endometrial epithelial cells and assayed different concentrations of estradiol (E2) and progesterone (P4) with respect to secretion of epidermal growth factor (EGF) and insulin-like growth factor-1 (IGF-1). Uterine epithelia were confirmed with Feulgen staining, karyotype analysis, and immunohistochemistry. Then, cells were treated with E2 and P4 and cultured in serum-free medium for 24 h. EGF and IGF-1 were measured with immunofluorescence, Real-time PCR (RT-PCR), Western blot (WB), and ELISA. When E2 and P4 were applied separately, the expression of EGF and IGF-1 did not change significantly, and EGF and IGF-1 gene and protein expression and epidermal growth factor receptor (EGFR) and insulin-like growth factor receptor (IGFR) gene expression were significantly increased when both hormones were combined. When the hormones were used singly, the optimal concentration of E2 was 10 ng/mL and of P4 was 100 ng/mL. When combined, the optimal E2 concentration was 10 ng/mL and P4 was 10 ng/mL. Thus, E2 and P4 can modulate expression of EGF and IGF-1 in endometrial epithelial cells at the morphological, gene, protein, and exocrine level, which is of great significance to improve the rate of yak embryo implantation and reproduction.