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Wednesday 01 June 2005

In vitro effects of deoxynivalenol on electrical properties of intestinal mucosa of laying hens.

By: Awad WA, Bohm J, Razzazi-Fazeli E, Zentek J.

Poult Sci 2005 Jun;84(6):921-7

Deoxynivalenol (DON) is common in European cereal grains, and of all the trichothecenes, poses the greatest problems to animal health. The present study investigated the effects of DON on electrophysiological parameters in laying hens' jejunum mounted in Ussing chambers. In vitro studies were performed to measure the effects of different luminal concentrations of DON (0.5, 1, 5, and 10 microg/mL) on the transmural potential difference, electrical tissue resistance, and electrogenic ion flux rates (short-circuit current, Isc) across the isolated gut mucosa. Deoxynivalenol did not alter (P > 0.05) the transmural potential difference. Resistance was higher (P < 0.05) in the tissues exposed to DON compared with basal values. Deoxynivalenol caused a dose-dependent decrease in Isc (P < 0.05). To investigate the mechanism of action of DON, amiloride (a specific inhibitor for Na+ transport) was added after incubation of the tissue with DON. Amiloride did not decrease (P > 0.05) Isc under these conditions. This may indicate that DON inhibited the Na+ transport before addition of amiloride, which did not then show further inhibitory effects. The addition of D-glucose (5 mmol/L) on the luminal side of the isolated mucosa increased (P < 0.05) Isc, and this effect was reversed by phlorizin (a specific inhibitor of sodium/glucose transporter 1), indicating that the glucose-induced Isc increase may be due to Na+-D-glucose cotransport. In our study, DON decreased (P < 0.05) the glucose-induced Isc in a similar way to phlorizin. The remarkable similarity between the effects of phlorizin and DON on electrical properties seemed to be consistent with their common ability to inhibit Na+-D-glucose cotransport. In conclusion, DON decreased the Isc via inhibition of Na+ transport. The effect on intestinal electrical properties was similar to that of phlorizin after addition of glucose, suggesting that DON may inhibit Na+-D-glucose cotransport. The inhibition of Na+ transport and Na+-D-glucose cotransport are important mechanisms of DON toxicity in the intestine of laying hens.

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