[Insulin Receptor in human placenta and its function]

Characteristic of insulin receptor in human placental villi with relation to glucose uptake and glycogenesis was studied in vitro. The specific binding of 125I-insulin to placental villi membranes was measured significantly higher in early placenta than in term placenta, while Scatchard plots analysis showed curvilinear, which indicated the binding affinity was approximately the same between them. However the binding capacity was higher in early placenta than in term placenta. The addition of insulin to placental villi in vitro showed increased glucose uptake, glycogen content and glycogen synthetase I form activity both in early and term placental villi. The glucose uptake, glycogen content and glycogen synthetase (total and I form) activity were higher in early placental villi than in term placental villi, but there was no significant difference in glycogen phosphorylase (total and active form). Collectively, the data suggest the presence of insulin receptor in placental villi varying its concentration with gestational age, where insulin plays a role in adjusting glucose uptake and glycogenesis.