AIM:To elucidate the chemopreventive efficacy of selenium during experimentally induced colon carcinogenesis.METHODS:Thirty-two male wistar rats were divided into four groups:group □(normal control);group □[1,2-dimethylhydrazine(DMH) treated];group □ (selenium treated);and group □ (DMH + selenium treated).Groups □ and □ were given subcutaneous injections of DMH(30 mg/kg body weight) every week for 20 wk.Selenium,in the form of sodium selenite,was given to groups □ and at 1 ppm in drinking water ad libitum for 20 wk.At the end of the study,rats were sacrificed and their colons were analyzed for the development of tumors,antioxidant enzyme levels and histological changes.RESULTS:100 of the DMH treated rats developed tumors,which was reduced to 60 upon simultaneous selenium supplementation.Similarly,tumor multiplicity decreased to 1.1 following selenium supplementation to DMH treated rats.Levels of lipid peroxidation,glutathione-S-transferase,superoxide dismutase(SOD),catalase,and glutathione peroxidase(GPx) decreased following DMH treatment,whereas levels of glutathione(GSH) and glutathione reductase(GR) significantly increased in DMH treated rats.Selenium administration to DMH treated rats led to an increase in the levels of lipid peroxidation,SOD,catalase,glutathione-S-transferase and GPx,but decreased the levels of GSH and GR.Histopathological studies on DMH treated rats revealed dysplasia of the colonic histoarchitecture,which showed signs of improvement following selenium treatment.CONCLUSION:The study suggests the antioxidative potential of selenium is a major factor in providing protection from development of experimentally induced colon carcinogenesis. AIM: To elucidate the chemopreventive efficacy of selenium during experimentally induced colon carcinogenesis. METHODS: Thirty-two male wistar rats were divided into four groups: group □ (normal control); group □ [1,2-dimethylhydrazine (DMH) treated] group □ (selenium treated); and group □ (DMH + selenium treated) .Groups □ and □ were given subcutaneous injections of DMH (30 mg / kg body weight) every week for 20 weeks. Selenium, in the form of sodium selenite, was given to groups □ and at 1 ppm in drinking water ad libitum for 20 wk. At the end of the study, rats were sacrificed and their colons were analyzed for the development of tumors, antioxidant enzyme levels and histological changes .RESULTS: 100 of the DMH treated rats developed tumors, which were reduced to 60 upon simultaneous selenium supplementation. Similarly, tumor multiplicity reduced to 1.1 following selenium supplementation to DMH treated rats. Levels of lipid peroxidation, glutathione-S-transferase, superoxide dismutase (SOD) se, and glutathione peroxidase (GPx) decreased following DMH treated rats, while levels of glutathione (GSH) and glutathione reductase (GR) increased significantly in DMH treated rats. Selenium administration to DMH treated rats led to an increase in the levels of lipid peroxidation, SOD, catalase, glutathione-S-transferase and GPx, but decreased the levels of GSH and GR. Histopathological studies on DMH treated rats revealed dysplasia of the colonic histoarchitecture, which showed signs of improvement following selenium treatment. CONCLUSION: The study suggests the the antioxidant potential of selenium is a major factor in providing protection from development of experimentally induced colon carcinogenesis.