Secretion of inhibin A and inhibin B during pregnancy and early postpartum period in Japanese monkeys.

In order to determine the profiles and sources of inhibin A and inhibin B during pregnancy in Japanese monkeys, serum samples were collected from eight monkeys for measuring concentrations of both inhibins by enzyme-linked immunosorbent assay. The term placenta was used for the localization of inhibin alpha-, betaA-, and betaB-subunits by immunohistochemistry. Serum concentrations of inhibin A showed a significant rise at the second quarter and maintained its level until term. Serum concentrations of inhibin B gradually increased until the fourth quarter. The concentration of both inhibins abruptly declined after delivery to the nonpregnant level. Positive staining of inhibin alpha-, betaA-, and betaB-subunits was observed in syncytiotrophoblast in the placenta by immunohistochemistry. These results demonstrated that large amounts of both dimeric inhibins are secreted from the placenta of Japanese monkeys.