Possible involvement of very low density lipoproteins in steroidogenesis in the human ovary

To determine whether human luteal cells can utilize very low density lipoproteins (VLDL)-carried cholesterol for steroidogenesis, we investigated the expression of VLDL receptor mRNA in human ovarian tissues and progesterone production by human luteinized granulosa cells after the addition of VLDL. The production of progesterone in the presence of human chorionic gonadotrophin (HCG) was increased significantly (P < 0.05) by VLDL (2479 +/- 1477 ng/10(5) cells, mean +/- SD, n = 6) and low density lipoproteins (LDL) (2726 +/- 1287), in comparison with the level in the absence of these lipoproteins (1350 +/- 739). Northern blot analysis revealed that the levels of expression of VLDL and LDL receptor mRNA in granulosa cells were almost equal to those in whole ovarian tissue. VLDL receptor mRNA was abundant in granulosa cells of preovulatory follicles and cells of the corpus luteum. Preovulatory thecal cells and stromal cells expressed lower amounts of VLDL receptor mRNA than granulosa cells of preovulatory follicles and cells of the corpus luteum. From the present study, it might be suggested that VLDL is utilized for steroidogenesis in human luteinized granulosa cells.