Thyme and cinnamon extracts induce anion secretion in piglet small intestine via cholinergic pathways

Thymol and cinnamaldehyde, extracted from thyme and cinnamon respectively, have multiple effects on mammalian cells. Although the intestinal mucosa is one of the first tissues they are in contact with when ingested, their effect on intestinal epithelial cells and especially ion secretion has not been established yet. The aim of this study was to investigate the effect of those two substances on electrolyte secretion and absorption across the porcine jejunal epithelium in Ussing chambers. Jejunal tissues from piglets were mounted in Ussing chambers and the short circuit current measured (Isc) after addition of thymol or cinnamaldehyde. Thymol and cinnamaldehyde induced a dose-dependent increase is Isc. The effect of thymol was inhibited in low Cl-, HCO3- free or low Cl-/ HCO3- free buffers. It was completely blocked when tissues were previously incubated with tetrodotxin and partially inhibited with hexamethonium. Cinnamaldehyde effect was inhibited when HCO3- free or low Cl-/ HCO3- free buffers were used. It was not affected by tetrodotoxin but reduced by hexamethonium, suggesting direct activation of receptors on epithelial cells. In conclusion, thymol induces Cl- and HCO3- secretion via activation of nervous nicotinic receptors while cinnamaldehyde induces HCO3- secretion probably via direct activation of nicotinic receptors on epithelial cells.