Regulation of low density lipoprotein receptor mRNA levels by estradiol 17beta and chorionic gonadotropin in human placenta

Abstract

Inhibition of synthesis of estradiol 17beta by the addition of inhibitors of aromatase, a key enzyme in the biosynthesis of estradiol 17beta, or addition of tamoxifen - an estrogen receptor antagonist, to human placental minces resulted in an increase in the level of LDL-receptor mRNA. This increase could be blocked by the simultaneous addition of estradiol 17beta. A concentration dependent effect of estradiol 17beta on the level of LDL-receptor mRNA was seen both in first trimester, and term placenta. Addition of human chorionic gonadotropin (hCG) to term placental minces also increased the LDL-receptor mRNA levels. When hCG and cycloheximide were added together, an additive effect was observed. The results obtained in this study suggest that the LDL-receptor mRNA levels in the human placenta are regulated by estradiol 17beta and hCG.