, Volume 44, Issue 11, pp 2359-2368

Effect of Saccharomyces boulardii on cAMP- and Ca2+-dependent Cl- Secretion in T84 Cells

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Abstract

Several reports have confirmed that thecooperative interaction between cAMP- andCa2+-mediated transduction pathways maycontribute to the stimulatory or inhibitory regulationof Cl- secretion in intestinal epithelium.Saccharomyces boulardii has been shown to inhibitcholera toxin-induced secretion in rat jejunum. We haveidentified a 120-kDa protein in medium conditioned bySaccharomyces boulardii that reduces cholera toxin-inducedcAMP in intestinal cells. The present study evaluatedthe effect of medium conditioned by Saccharomycesboulardii on cAMP- and Ca2+-mediatedCl- secretion in T84 cells. Experiments performedwith cAMP agonists revealed that 1 hr of preincubationof cells with medium conditioned by Saccharomycesboulardii was necessary to elicit a 40-50% reduction in receptor (cholera toxin, prostaglandinE2, and vasoactive intestinal polypeptide)and nonreceptor (forskolin) mediated cAMP synthesis and125I- efflux. Secretion induced by carbachol was inhibited when cells werepretreated for 1 hr with medium conditioned bySaccharomyces boulardii despite the absence ofinhibition of Ins (1,4,5)P3. From this studywe conclude that Saccharomyces boulardii exerts aninhibitory effect in vitro on Cl- secretionmediated through both cAMP- and Ca2+-mediatedsignaling pathways.