Hyperinsulinemia increases placenta endothelin-converting enzyme-1 expression in trophoblasts

Area of Science:

• Reproductive biology
• Endocrinology
• Vascular physiology

Background:

• Exogenous hyperinsulinemia in pregnant rats induces hypertension and intrauterine growth restriction (IUGR).
• Hyperinsulinemia may elevate endothelin-1 (ET-1) production.
• Endothelin-converting enzyme-1 (ECE-1) mediates ET-1 production, and its expression is investigated in key organs.

Purpose of the Study:

• To investigate the expression of ECE-1 in the placenta, kidney, heart, and liver of hyperinsulinemic pregnant rats.
• To examine the expression of endothelin receptor A (ET-A) in the placenta and its implantation site.
• To correlate ECE-1 and ET-A expression with pregnancy-induced hypertension and IUGR.

Main Methods:

• Rats were made hyperinsulinemic via insulin pellets and mated.
• Pregnancy was monitored until day 21, followed by examination of dams, fetuses, and placentas.
• ECE-1 and ET-A expression were quantified using Western blot and immunohistochemistry.

Main Results:

• Hyperinsulinemic dams exhibited elevated blood pressure, reduced placental weight, and lower fetal weights compared to controls.
• ECE-1 protein expression was significantly increased in the placenta, kidney, and heart of hyperinsulinemic dams.
• ECE-1 and ET-A were localized in placental endothelial and trophoblastic cells, with generally stronger expression in hyperinsulinemic dams.

Conclusions:

• ECE-1 and ET-A are expressed in placental trophoblastic cells and the mesometrial triangle.
• Altered expression of ECE-1 and ET-A may contribute to elevated endothelin levels, hypertension, and IUGR during hyperinsulinemia.
• These findings highlight a potential mechanism linking metabolic disturbances to adverse pregnancy outcomes.