Isolated swine granulosa cells incubated in chemically defined medium in vitro responded to synthetically pure human somatomedin C IGF-I in a dose and time-dependent fashion with increased pregnenolone, progesterone and estradiol biosynthesis. These stimulatory actions were not mimicked by growth hormone, proinsulin, desoctapeptide insulin, epidermal growth factor, or fibroblast growth factor. Moreover, somatomedin C IGF-I augmented the steroidogenic response of granulosa cells to exogenously supplied sterol substrate in the form of low-density lipoprotein, and amplified the stimulatory actions of the classical ovarian effector hormones, estradiol and follicle-stimulating hormone, in a synergistic fashion. The ability of somatomedin C IGF-I to stimulate estradiol production on the one hand, and to act synergistically with estradiol to stimulate progesterone biosynthesis on the other hand, suggests a unique intrafollicular mechanism for amplifying progestin biosynthetic capacity in granulosa cells.
|Original language||English (US)|
|Number of pages||7|
|Journal||Biochemical and Biophysical Research Communications|
|State||Published - Jul 16 1985|
ASJC Scopus subject areas
- Molecular Biology
- Cell Biology