Inhibin expression in normal and pre-eclamptic placental tissue

Serum inhibin levels increase during normal pregnancy, but are significantly higher in patients with pre-eclampsia. The aim of this study was to demonstrate possible increased expression of inhibin within the placentas of women with preeclampsia compared with non-prl-eclamptic controls. Cellular expression of inhibin alpha and beta(A) subunits was studied using immunohistochemistry on formalin-fixed, paraffin-embedded placental sections from cases of pre-eclampsia (n = 23) and gestational age-matched non-pre-eclamptic controls (n = 16). Immunohistochemistry was per formed using monoclonal antibodies against inhibin alpha and beta(A) subunits by the indirect immunoperoxidase technique. intensity of staining was graded by a semiquantitative scoring method. Differences in distribution and intensity of staining between control and pre-eclamptic placentas were analyzed using a nonparametric Mann-Whitney U test. Staining for both inhibin alpha and beta(A) was predominantly confined to the cytoplasm of syncytiotrophoblast, with weak expression within intermediate trophoblast. The intensity of staining for inhibin a: was significantly greater in the syncytiotrophoblast of pre-eclamptic patients (mean staining intensity controls = 0.97, disease = 1.87; p < 0.001). inhibin beta(A) staining was generally stronger than for the a: subunit, and was also significantly increased in pre-eclamptic patients compared with controls (mean controls = 1.72, disease 2.19; p < 0.05). This: is the first evidence for increased placental inhibin presence in pre-eclampsia, suggesting increased inhibin production within the placenta, a finding that could account for increased serum inhibin levels in pre-eclampsia.