Effects of basic fibroblast growth factor and heparin on follicle-stimulating hormone-induced steroidogenesis by bovine granulosa cells1

The objectives of the present study were to determine the effect of and interaction between basic fibroblast growth factor (bFGF) and heparin, a major bFGF-binding protein, on bovine granulosa cell estradiol and progesterone production. Cells from small (1 to 5 mm) follicles were collected from cattle, cultured for 2 d in medium containing 10% fetal calf serum, and then treated for 1 d with bFGF and(or) heparin in serum-free medium. Treatment with .1 to 10 micrograms/mL of heparin for 1 d had no effect (P > .05), whereas 100 micrograms/mL of heparin inhibited (P < .05) FSH-induced estradiol production by bovine granulosa cells. Treatment with .1 to 1.0 ng/mL of bFGF for 1 d, supplied with human serum albumin as a carrier protein, inhibited (P < .05) FSH-induced estradiol production by bovine granulosa cells, with the greatest inhibition detected at 1.0 ng/mL; coculture with 10 micrograms/mL of heparin did not influence these effects. In comparison, .1 ng/mL of bFGF supplied carrier-free had no effect (P > .05) on FSH-induced estradiol production, whereas 1.0 to 100 ng/mL of carrier-free bFGF inhibited (P < .05) FSH-induced estradiol production, with the greatest inhibition detected at 100 ng/mL. The presence of heparin (10 micrograms/mL) had variable effects on granulosa cell estradiol and progesterone production inhibited by carrier-free bFGF. These results indicate that bFGF may play a significant role in FSH-modulated granulosa cell steroidogenesis during follicular development in cattle.