Immunolocalization Of Adipocytes And The EP₁、EP₃Receptor Proteins Of PGE₂and Its Related Synthetase MRNA Detection In The Caprine Cervix During Different Reproductive Periods

The cervix of mammal is the part of vaginal delivery and fertilization pathways, andparturition will be launched after cervical ripening. Prostaglandin E₂（PGE₂） could loose up thecervix sphincter, and be thought as the important factor in cervical ripening promotion. Inother words, Prostaglandin E₂take part in the starting process of parturition, or promotecervical soften, dilate and ripening. Prostaglandin E₂receptors（EP） have four kinds ofsubtypes, including EP₁, EP₂, EP₃and EP4, EP₁and EP₃receptors activation usually lead tosmooth muscle contraction, which also be called contractile or excited receptors; EP₂and EP4receptors activation usually lead to smooth muscle relaxation, which also be called relaxed orinhibitory receptors. The determining factor in various action of PGs on cervical reactivitymay lie in differential expression of the various informs during different reproductive periodsin mammals.Information is lacking about the localization of PGE₂-producing cells and PGE₂receptors （EP） in intrapartum cervix and whether cervical dilation at parturition is an activeprocess. The mechanisms of cervical ripening and dilation in mammals remain obscure. Toreveal these mechanisms, the specificity of the different rabbit anti-human polyclonalantibodies for EP₁and EP₃contractile receptor proteins of PGE₂and perilipin A in intrapartumcaprine cervices was assayed by Western-blot analysis; immunolocalization of EP₁and EP₃contractile receptor proteins of PGE₂（official gene symbols PTGER1and PTGER3） andPGE₂-producing cells in caprine cervix during nonpregnancy, pregnancy, and parturition wasassayed by immunohistochemistry （IHC）; the mRNA expression levels of PTGES, PTGES2,PTGER1（EP₁）, and PTGER3（EP₃） were determined using quantitative PCR; and theexistence of adipocytes in the cervix at various stages was demonstrated with Oil Red Ostaining and IHC of perilipin A. The results suggested that EP₁was detected mainly in arterioles and canal or glandular epithelia; and EP₃was poorly expressed only in stroma, canalepithelia, and circular muscles. The strong expression of EP₃was observed duringnonpregnancy and pregnancy except for the strong expression of EP₁in canal or glandularepithelia during pregnancy. The mRNA expression levels of PTGES, PTGES2, PTGER1, andPTGER3were significantly higher in nonpregnant than midpregnant and intrapartum cervices（P<0.01）. Adipocytes appear only in the intrapartum cervix. These results support the conceptthat PGE₂modulates specific functions in various anatomical structures of the caprine cervixat labor and the appearance of adipocytes at labor is likely related to caprine cervical dilation.