INTRACRINE ROLE OF PROGESTERONE IN FOLLICLE-STIMULATING HORMONE-INDUCED AND CYCLIC ADENOSINE 3',5'-MONOPHOSPHATE-INDUCED FIBRONECTIN PRODUCTION AND DEPOSITION BY CHICKEN GRANULOSA-CELLS - INFLUENCE OF FOLLICULAR DEVELOPMENT

The role of progesterone in FSH- and 8-bromo-cAMP (8-Br-cAMP)-induced fibronectin production by chicken ovarian granulosa cells was examined . Granulosa cells isolated from the third largest (F-3; developing; 15 -20 mm in diameter) preovulatory follicle and a pool of immature small yellow follicles (SYF; 6-8 mm in diameter) were incubated in serum-fr ee medium 199, and the total amount of fibronectin produced (deposited , secreted into the medium, and associated with cells) was measured by enzyme-linked immunosorbent assay. Unstimulated F-3 cells deposited g reater amounts of fibronectin than unstimulated SYF cells. FSH or 8-Br -cAMP significantly increased fibronectin deposition. Similarly, both agents increased the quantity of fibronectin secreted into the medium and that associated with cells. The magnitude of FSH- and 8-Br-cAMP-en hanced fibronectin deposition or secretion into medium by SYF cells wa s greater than that by F-3 cells. Cyanoketone (an inhibitor of progest erone synthesis) significantly suppressed basal fibronectin production by F-3 cells, but not that by SYF cells. Cyanoketone completely block ed FSH or 8-Br-cAMP-induced fibronectin production by F-3 cells, but c aused only a modest inhibition (nonsignificant) of agonist-induced fib ronectin production by SYF cells. Exogenous progesterone completely re versed the inhibitory effects of cyanoketone on agonist-induced fibron ectin production. The nondegradable synthetic progestin R5020 also rev ersed the inhibitory effects of cyanoketone on agonist-induced fibrone ctin production. The antiprogestin, ZK 98.299, inhibited basal and FSH -stimulated fibronectin production. The data demonstrate that FSH- and cAMP-stimulated fibronectin production by chicken granulosa cells is dependent (at least in part) on de novo progesterone synthesis. Furthe rmore, they indicate that fibronectin production and deposition by the se cells are stimulated by progesterone, perhaps in an intracrine/auto crine manner, and that the role of progesterone increases with advanci ng stages of follicular development.