[Effect of low density lipoprotein on intracellular cholesterol and progesterone production by monolayer cultured human luteal cells].

The purpose of the present study was to define the effect of low density lipoprotein (LDL) on progesterone (P) synthesis and on intracellular cholesterol content using monolayer cultured human luteal cells. When cultured in TC199 containing 10% lipoprotein poor serum (LPPS), P production decreased as culture time passed. In the presence of hCG, it also decreased, but slowly. In the presence of LDL, P production was kept at a higher level. Intracellular cholesterol content in luteal cells was measured by gas chromatography. The cholesterol content of luteal cells in a 4 day LPPS culture was higher than that in a 10 day LPPS culture. The cholesterol content in a 10 day LPPS culture with LDL was higher than that in a 10 day LPPS culture. The cholesterol content in a 10 day LPPS culture with hCG had a tendency to be lower than that in a 10 day LPPS culture, but there was no statistical difference (p less than 0.1). It was concluded that LDL was utilized in supplying intracellular cholesterol to luteal cells as a substrate for P synthesis. And in a state of LDL depletion in the medium, the luteal cells produced a small amount of P utilizing intracellular cholesterol. It was estimated from the results of the present study that hCG enhanced utilization of intracellular cholesterol.