INHIBIN AND ACTIVIN IN HUMAN FETAL MEMBRANES - EVIDENCE FOR A LOCAL EFFECT ON PROSTAGLANDIN RELEASE

Trophoblast and fetal membranes (amnion and chorion) are the tissues f orming the anatomical/functional interface between the mother and the fetus. The aim of the present study was to evaluate the presence and a possible effect of inhibin and activin in human amnion and chorion. T he expression of inhibin/activin alpha, betaA, and betaB subunit messe nger RNA (mRNA) and the localization of immunoreactive material were e valuated in amnion and chorion collected at term pregnancy by a Northe rn blot analysis and by immunohistochemistry. Amnion cells expressed t he mRNA of the three inhibin/activin subunits, with the betaB message the most abundantly expressed. The epithelial layer of the amnion show ed an intense fluorescent staining of betaB inhibin/activin subunit, a nd positive signals were also observed for the alpha and betaA subunit s. Inhibin/activin alpha and betaA subunit mRNAs were found highly exp ressed in chorion. The cytotrophoblast of the chorion showed a positiv e staining for the three inhibin/activin subunit antisera. The additio n of activin A increased the release of prostaglandin E2 from human am nion-derived cultured cells. The effect was dose and time dependent. I nhibin A did not induce significant changes of prostaglandin E2 releas e from amnion cells. The present results show that amnion and chorion produce inhibin and activin subunits and that activin stimulates the r elease of prostaglandin E2 from cultured amnion cells, suggesting a po ssible role of inhibin and activin in fetal membranes.