ACTIVIN AT PARTURITION - CHANGES OF MATERNAL SERUM LEVELS AND EVIDENCE FOR BINDING-SITES IN PLACENTA AND FETAL MEMBRANES

Objective: To evaluate maternal serum activin A levels in pregnant wom en at parturition, correlated to the mode of delivery, and to localize activin receptor messenger RNA in human placenta and fetal membranes. Methods: A specific two-site enzyme-linked immunosorbent assay (ELISA ) was used to measure maternal activin A levels. Activin receptor mRNA was localized in placenta and fetal membranes by in situ hybridizatio n, using ActRII or ActRIIB antisense riboprobes. Results: Serum activi n A levels increased significantly in pregnant women during vaginal or cesarean delivery after spontaneous labor. No significant changes of serum activin A were found in patients undergoing elective cesarean de livery. Syncytiotrophoblast and amnion cells hybridized to radiolabele d ActRIIB probe, whereas few cells within the structure of the villi a nd decidual cells hybridized to radiolabeled ActRII probe. Conclusion: The present studies indicate that vaginal or cesarean delivery follow ing spontaneous labor is characterized by increased activin A levels a nd that activin receptors are present on trophoblast and fetal membran es.