EFFECT OF SELENIUM ON THE ANTIOXIDATIVE ENZYMES IN RATS WITH MAMMARY-TUMOR INDUCED BY 7,12-DIMETHYLBENZ(A)ANTHRACENE

The biological impact of selenium on the levels of antioxidant enzymes in Wistar rats bearing mammary tumor induced by dimethylbenz(a)anthra cene was investigated. Control rats and tumor-bearing rats were fed a normal diet or one containing 5 mg sodium selenite/kg diet from the da y of tumor induction. The reduced levels of ceruloplasmin, ascorbic ac id, and alpha-tocopherol seen in the serum of tumor-bearing rats on th e normal diet were found to be increased by the selenium treatment. Th e activities of superoxide dismutase and catalase in tumor-bearing rat s were decreased significantly when compared with those of control rat s, whereas selenium administration caused a considerable recovery of t he activities of these enzymes in the rats with tumors. The increase i n the levels of these enzymes was found to be predominantly significan t in the liver. These observations clearly suggest an antioxidant role for selenium in experimental mammary tumor.