Discordance in the effects of interleukin-1 on rat granulosa cell differentiation induced by follicle-stimulating hormone or activators of adenylate cyclase.

Abstract

Recombinant human interleukin-1 (IL-1) inhibits the follicle-stimulating hormone (FSH)-induced development of luteinizing hormone (LH) receptors and suppresses progesterone secretion in cultured rat granulosa cells. Since activation of adenylate cyclase by FSH is considered to be the primary second messenger system responsible for differentiation of granulosa cells, we examined whether IL-1 could alter the FSH, cholera toxin, or forskolin-induced accumulation of cyclic adenosine 3', 5'-monophosphate (cAMP) from these cells. In addition, we sought to determine if IL-1 could influence differentiation induced by the cAMP analog, 8-bromo cAMP. Cells collected from ovaries of immature, diethylstilbestrol-treated rats were stimulated to differentiate by addition of FSH, cholera toxin, forskolin, or 8-bromo cAMP to the cultures. IL-1 or interleukin-2 (IL-2) was added to some of the tubes, and the primary cultures were incubated for various periods of time. At the end of the culture, the tubes were centrifuged, the medium was saved for progesterone and cAMP radioimmunoassay, and the cells were assayed for specific 125I-human chorionic gonadotropin (hCG) binding to determine the number of LH receptors. In the presence of FSH, IL-1, at a dose as small as 5 ng/ml, but not IL-2, significantly inhibited LH receptor formation and suppressed progesterone secretion in a dose-related manner. IL-1 also significantly suppressed FSH-induced cAMP accumulation after 72 h of incubation but did not appear to do so in a dose-related fashion. In the presence of FSH, IL-1 did not significantly alter the protein content of granulosa cells at the end of culture. During stimulation of granulosa cells with cholera toxin, forskolin, or 8-bromo cAMP, IL-1 significantly reduced LH receptor formation compared to that observed in the absence of IL-1. However, in contrast to IL-1 in the presence of FSH, IL-1 significantly augmented the forskolin-induced secretion of progesterone and accumulation of cAMP after 72 h at subsaturating doses of forskolin. Thus, IL-1 appeared to inhibit forskolin-induced and cholera toxin-induced formation of LH receptors even when cAMP levels were elevated. Similar to forskolin, 8-bromo cAMP-stimulated progesterone secretion was significantly enhanced by IL-1, but LH receptor formation was inhibited. Over a 72-h time course at single doses of FSH or forskolin, IL-1 did not affect cAMP accumulation until 48 h of culture, at which time IL-1 significantly suppressed FSH-induced, but augmented forskolin-induced, accumulation of cAMP.(ABSTRACT TRUNCATED AT 400 WORDS)