Ethanol and the antioxidant defense in the gastrointestinal tract.

Ethanol is known to have profound actions on the gastrointestinal tract. The present study was undertaken to examine the effects of ethanol on some of the natural antioxidant defensive enzymes in the gastrointestinal tract; the activities of these enzymes in the liver and the brain were also measured for comparison with those in the gastrointestinal tract. Oral administration of absolute ethanol induced severe gastric mucosal lesions and also damage in the small intestine, however the total superoxide dismutase was unaffected in the tissues measured. The glucose-6-phosphate dehydrogenase activity was reduced only in the stomach while the total glutathione was elevated in the small intestinal mucosa. The catalase activities were activated in the stomach, small and large intestines, and brain, but not in the liver which contained the highest concentration of the enzyme. The present findings indicate that endogenous hydrogen peroxide may be an important damaging agent towards biomolecules in different organs and the removal of this by catalase represents an important defensive mechanism against ethanol toxicity.