Abstract
Prostaglandins produced within the CL may serve as local modulators of CL function. The present study was designed to characterize the cellular mechanisms by which the cytokine interleukin-1 beta (IL-1 beta) stimulates prostaglandin production in cultured luteal cells. Cycloheximide (CHX) and actinomycin D (Act D) did not affect basal, but completely inhibited IL-1 beta-stimulated prostaglandin F2 alpha (PGF2 alpha) production (p < 0.05). The phospholipase A2 (PLA2) inhibitor, aristolochic acid (PLA2X), and the phospholipase C (PLC) inhibitor, compound 48/80 (PLCX), suppressed IL-1 beta-stimulated (p < 0.05), but not basal, PGF2 alpha production. The addition of exogenous arachidonic acid (AA) restored the stimulatory effect of IL-1 beta in PLCX-treated, but not in PLA2X-treated, cells, suggesting that PLA2 is a key regulatory point of IL-1 beta action. Chronic exposure of the luteal cells to IL-1 beta resulted in stimulatory effects beyond that of increasing AA availability, presumably by up-regulation of prostaglandin endoperoxide (PGH) synthase. Chronic exposure of luteal cells to IL-1 beta also inhibited progesterone production, but this effect appeared to be independent of endogenous PGF2 alpha production. The ability of IL-1 beta to comprehensively stimulate luteal PGF2 alpha production while inhibiting luteal progesterone production is suggestive that IL-1 beta may facilitate regression of the CL.

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