Follicle-stimulating hormone induces functional receptors for basic fibroblast growth factor in rat granulosa cells

In the present study we examined the existence of receptors for basic fibroblast growth factor (bFGF) and its regulation in rat granulosa cells. The binding of labeled bFGF to rat granulosa cells was dose-dependently displaced by unlabeled bFGF, but not other growth factors. FSH induced a dose-dependent increase in specific binding for bFGF to cultured rat granulosa cells. FSH treatment did not change the binding affinity (Kd, 2.8-3.0 x 10(-10) M) of the bFGF receptor, but increased the total number of bFGF-binding sites, whereas treatment with several steroid hormones had no effect on the specific binding of bFGF. Since cycloheximide, a protein synthesis inhibitor, inhibited the increase in bFGF binding induced by FSH, it is suggested that protein synthesis might be involved in the FSH stimulation of bFGF receptor induction. Furthermore, bFGF stimulated tissue plasminogen activator activity in a dose-dependent manner, and FSH-primed granulosa cells were more responsive to bFGF action, with a decrease in ...