PROTECTIVE EFFECTS OF ANTIOXIDANT ENZYMES AND GSH IN-VIVO ON IRON-MEDIATED LIPID-PEROXIDATION IN GASTROINTESTINAL-TRACT OF RAT

The protective mechanisms operating in the gastrointestinal (GI) tract to counteract the potential oxidizing effects of excess free iron, wa s tested in rats fed with excess iron. The activities of some antioxid ant enzymes, the levels of GSH and the extent of lipid peroxidation at the site of iron absorption were measured. Based on the amount of thi obarbituric acid reactive substances (TEARS) produced, it could be ded uced that the duodenal segment of GI tract is resistant to iron mediat ed lipid peroxidation. The duodenal function as judged from the activi ties of marker enzymes, namely, alkaline phosphatase and Lys-Ala-dipep tidyl aminopeptidase was normal. There was depletion of GSH possibly d ue to the increased activities of Cu, Zn SOD and catalase. However, th e activity of Gpx was decreased in the Fe fed group. It was also obser ved that the ratios of SOD/Gpx and Cat/Gpx had significantly increased in the treated group whereas SOD/Cat remained constant suggesting tha t antioxidative enzymes play a key role in rendering the intestinal mu cosal cells resistant to iron induced oxidative damage in rats.