[The effect of insulin-like growth factor-I on steroidogenesis and ultrastructures of cultured human granulosa cells in vitro].

OBJECTIVE

To observe the effect of insulin-like growth factor-I (IGF-I) on steroidogenesis and ultrastructures of cultured human granulosa cells in vitro and the synergetic influence of follicle stimulating hormone (FSH) on this process.

METHODS

Human granulosa cells were cultured in serum-free 1640 medium. After stimulated with various concentrations of IGF-I or IGF-I + FSH for 24 hours, estradiol (E2) and progesterone (P) levels in the media were measured by radioimmunoassay, and the ultrastructure changes of granulosa cells were observed under electronic microscope.

RESULTS

When stimulated with different concentrations of IGF-I for 24 hours, E2 and P levels produced by granulosa cells were in a dose-dependent manner and significantly higher than those of controls (P < 0.01). The E2 and P levels in the media under the stimulation of IGF-I + FSH were 3.5 times and 14.5 times respectively higher than those of FSH alone. The main ultrastructureal appearances of granulosa cells stimulated with IGF-I were abundance of enlarged smooth enodplasmic reticulum, mitochondria and lipid droplets in cytoplasm.

CONCLUSIONS

IGF-I possesses a positive effect on the steroidogenesis of cultured human granulosa cells in dose-dependent fashion which could be enhanced by combination of IGF-I and FSH. The ultrastructures of granulosa cells showed a tendency toward activation of steroidogenesis under the stimulation of IGF-I.