PROGESTERONE STIMULATES FIBRONECTIN PRODUCTION BY CHICKEN GRANULOSA-CELLS IN-VITRO

Experiments were conducted in vitro to examine the effect of progester one on fibronectin production by chicken ovarian granulosa cells. Gran ulosa cells isolated from the largest (F-1; mature) and third-largest (F-3; developing) preovulatory follicles as well as from a pool of imm ature small yellow follicles (SYF) of the domestic chicken ovary were incubated in serum-free Medium-199 and the amounts of fibronectin and progesterone produced were quantified by enzyme-linked immunosorbent a ssay and radioimmunoassay, respectively. The amounts of basal bronecti n and progesterone produced by granulosa cells from F-1, F-3 and SYF f ollicles increased with advancing stages of follicular development. Th us, the quantity of basal fibronectin secreted by granulosa cells was directly proportional to the amount of progesterone produced by them. Exogenously supplied progesterone increased the amount of fibronectin secreted by F-1 and F-3 cells in a dose-dependent manner, but its effe ct on SYF cells was marginal. Cyanoketone (an inhibitor of progesteron e synthesis) suppressed basal fibronectin production by F-1 and F-3 gr anulosa cells and its inhibitory action was reversed by exogenous prog esterone. The progesterone antagonist RU 486 also attenuated basal fib ronectin production by F-1 and F-3 granulosa cells, but only the highe st concentration affected SYF cells. The inhibitory effect of RU 486 w as diminished in the presence of exogenous progesterone. These data sh ow that progesterone regulates fibronectin production by chicken granu losa cells. They suggest that in avian granulosa cells, endogenous pro gesterone can stimulate fibronectin synthesis in an intracrine or auto crine manner.