Expression and regulation of prostaglandin receptors in the human placenta and fetal membranes at term and preterm

Prostaglandins (PGs) play an important role in parturition in many species, including humans. The present study examined the distribution of PG receptor subtypes (EP1-4 and FP) in intrauterine tissues at term and preterm birth. Placentas and fetal membranes were collected from patients at term in labour (n = 12) or not in labour (n = 12). Preterm tissue was collected from three different groups of patients: (1) idiopathic preterm labour (PTL) without chorioamnionitis or betamethasone (BM) treatment (n = 9), (2) idiopathic PTL that received BM with no chorioamnionitis (PTL-BM; n = 9) and (3) pregnancies that were complicated with chorioamnionitis and had no BM (PTL-CHA; n = 6). EP1-4 and FP receptors were localised and levels of expression were determined by western blot analysis. All EP receptors and FP were localised to the amnion, placenta and choriodecidua. Moreover, isolated amnion mesenchymal, amnion epithelial, chorion trophoblast and syncytiotrophoblast cells in primary culture also expressed PG receptors. A significant increase was observed in EP1, EP3 and FP expression in placenta, chorion and amnion with labour. Maternal betamethasone treatment increased EP1, EP3 and FP receptor protein expression and chorioamnionitis decreased expression in all the receptor subtypes. These changes in PG receptors in the fetal membranes are consistent with the development of a feed-forwards cascade mediated through PG action that may contribute to the birth process.