Apelin in Pregnancy and Hypertensive Disorders of Pregnancy

Abstract

Apelin binds to APJ (a putative receptor protein related to AT1) and has an antihypertensive function in an NO-dependent manner. Endothelial cell dysfunction is one of the mechanisms of hypertensive disorders of pregnancy (HDPs). To investigate the pathophysiology of HDP, the apelin concentration in blood was measured in patients with normal pregnancy, in their umbilical cord, and in patients with HDP using ELISA. The localization of apelin in the placenta was analyzed using immunohistochemistry. The concentration of apelin decreased throughout pregnancy and returned to nonpregnant levels 1 month after delivery. The apelin levels in patients with HDPs that developed after 32 weeks of gestation were significantly increased compared with those in patients with normal pregnancies in the third trimester. Apelin expression was found in the cytotrophoblasts of normal pregnancy placentas. No significant difference was found between placenta with normal pregnancy and HDP. The increased apelin levels in patients with HDPs may have antihypertensive effects by vasodilator mechanisms.