Thymol and trans-cinnamaldehyde reduce active nutrient absorption and chloride secretion in the pig jejunal Ussing chamber model

Thymol and trans-cinnamaldehyde have shown to exert antimicrobial properties against commensal and pathogenic bacteria of the porcine gut and therefore have gained interest for use in animal feeds. Here, we studied the effect of these compounds on Na(+)-dependent D-glucose and L-alanine absorption and stimulated Cl(-) secretion. Stripped mid-jejunal tissue of piglets was mounted in Ussing chambers. The increase in short-circuit current (Delta Isc) to mucosal addition of 16 mmol/L D-glucose and 16 mmol/L L-alanine, with or without pre-incubation with 0.2 and 1.0 mmol/L thymol or trans-cinnamaldehyde was determined. Accordingly, the effect on stimulated chloride secretion by secretagogues was measured. Both compounds reduced the Isc response to nutrients and secretagogues in a dose-dependent manner. Delta Isc to D-glucose for thymol at 0.2 and 1.0 mmol/L was 73.7 +/- 7.9 (P>0.05) and 23.8 +/- 7.4 mu A/cm(2) (P<0.001) respectively, compared to 80.1 +/- 7.4 mu A/cm(2) for the control treatment. Delta Isc to L-alanine for the same treatments was 20.6 +/- 2.3 (P=0.01) and 5.9 +/- 2.4 mu A/cm(2) (P<0.001) compared to 33.7 +/- 2.6 mu A/cm(2) for the control treatment. Trans-cinnamaldehyde showed only significant effects at 1 mmol/L Thymol and trans-cinnamaldehyde induced a greater reduction in secretory response to the cAMP/cGMP mediated secretagogues VIP and theophylline than to the Ca(2+) mediated secretagogues 5-HT and carbachol. (C) 2010 Elsevier B.V. All rights reserved.