Immunolocalization of Atrial Natriuretic Peptide and C-Type Natriuretic Peptide In Healthy and Pre-Eclamptic Human Placenta

Pregnancy triggers extensive alterations in the maternal vasculature to deliver a constant supply of blood to the growing fetus. Natriuretic peptides are hormones secreted by many organs. Preeclampsia is associated with increased maternal plasma natriuretic peptide levels, which are used as novel biochemical markers to predict the preeclampsia. Here, we aimed to determine the immunohistochemical distribution of atrial natriuretic peptide (ANP) and C-type natriuretic peptide (CNP) in normal and pre-eclamptic human placentas. Tissue samples from maternal and fetal parts of pre-eclamptic and healthy human placentas were subjected to routine tissue processing. Avidin-biotin-peroxidase complex (ABC) immunohistochemistry was applied to formalin-fixed, paraffin-embedded placenta sections collected onto poly-l-lysine slides to demonstrate ANP and CNP expression. Immunohistochemistry revealed immunoreactivity for ANP and CNP in fetal and maternal tissues. On the fetal side of the preeclampsia group, strong ANP and CNP immunoreactivity were detected in the amniotic epithelium, fetal vessels, villous syncytiotrophoblast plate, villous vascular endothelial cells and smooth muscle cells than the healthy group. On the maternal side of the pre-eclampsia group, decidual cells exhibited lower ANP and CNP immunoreactivity than healthy group. These data indicate that increased ANP and CNP expression relating to preeclampsia might serve as a compensatory function to properly maintain uteroplacental perfusion and fetal development during pregnancy