This study was conducted to evaluate the effects of several growth factors on plasminogen activator (PA) activity in granulosa and theca cells collected from the largest preovulatory follicle in the hen ovary and to determine the involvement of cyclic adenosine monophosphate (cAMP) or protein kinase C, or both, in mediating the actions of epidermal growth factor (EGF) on granulosa PA activity. The granulosa cells were treated with increasing concentrations of: EGF (.33 to 16.4 nM); insulin-like growth factor I (IGF-I, 2.61 to 131 nM); fibroblast growth factor (FGF, .15 to 7.5 nM); or platelet-derived growth factor (PDGF, .02 to 1 nM). The treatments resulted in a dose-dependent increase in both cell-associated and secreted enzyme activity. The stimulatory effects of IGF-I (131 nM), however, were not mimicked with an equimolar concentration of the related peptide, insulin-like growth factor II. By contrast, theca cell PA activity was not significantly altered by EGF (16.4 nM), IGF-I (131 nM), FGF (7.5 nM), or PDGF (1 nM). Accumulation of cAMP was measured following exposure of granulosa cells to luteinizing hormone (LH, 10 ng, used as a positive control) or to EGF (16.4 and 164 nM) in the presence of .1 mM isobutylmethylxanthine. A 5-fold increase in cAMP levels was observed in response to LH; however, granulosa cell cAMP production was not altered by the presence of EGF.(ABSTRACT TRUNCATED AT 250 WORDS)