Regulation of cytochrome P-450scc in immature porcine granulosa cells by FSH and estradiol.

FSH, estradiol, or a combination of FSH and estradiol enhanced secretion of progesterone by primary cultures of immature porcine granulosa cells; they also increased the mitochondrial content of cytochrome P-450 and mitochondrial cholesterol side-chain cleavage activity. FSH or estradiol alone increased mitochondrial cytochrome P-450 levels and cholesterol side-chain cleavage activity to a similar extent. The combination of FSH and estradiol further increased cytochrome P-450 and side-chain cleavage activity. Our results demonstrate that FSH, estrogen and the combination of the hormones stimulate progestin synthesis by granulosa cells, at least in part, by increasing cholesterol side-chain cleavage enzyme levels. These observations suggest a dual hormonal regulation of the enzyme catalyzing the rate-limiting step in the biosynthetic pathway of steroid hormones.