Prostanoid receptors EP2, EP4, and FP are regulated by estradiol in bovine oviductal smooth muscle.

Gamete and embryo transport is an important function of the oviduct. This transport involves both smooth muscle contraction and epithelial cell secretions, the former of which is mediated by prostaglandins (PGs) and their receptors. Our aim was to study the regulation of prostaglandin E2 and prostaglandin F2α receptors (EP2, EP4, and FP receptor) by estradiol in bovine oviduct smooth muscle. EP2, EP4, and FP receptor mRNA and protein expression was investigated using real-time RT-PCR and Western blot analyses, respectively. To evaluate the contraction or relaxation of cultured bovine oviductal smooth muscle tissue, peristalsis was used to assess contractile activity. EP2, EP4, and FP receptor mRNA and protein expression was increased in oviductal smooth muscle tissue after treatment with different concentrations of estradiol for various durations. The expression of all receptors peaked at an estradiol concentration of 10(-11)mol/L after 8h of treatment, whereas no increase in expression was observed after fulvestrant (a selective antagonist of E2 receptor) treatment, indicating that E2 interacts with specific E2 nuclear receptors to regulate EP2, EP4, and FP receptor expression. Although PGF2α and PGE2 induced both contraction and relaxation, no significant differences were found in contractility between the estradiol-treated and control groups, with both groups of cultured smooth muscle strips showing similar vitality. In conclusion, estradiol increases EP2, EP4, and FP receptor mRNA and protein expression in bovine oviductal smooth muscle when added for different periods of time and at different concentrations. Additionally, E2 is transported intracellularly and interacts with specific E2 nuclear receptors to regulate their expression.