This work aimed to study the protective effects of combined selenium (Se) and vitamin E (VE) on dimethylnitrosamine (DMN)-induced alterations in iosenzyme pattern and activitiy of some hepatic enzymes, namely aspartate aminotranferase (AST), alkaline phosphatase (ALP), lactate dehydrogenase (LDH) and esterase (EST) in male mice. Thirty five male mice were divided into seven groups, 5 mice each. These were: Control, DMN (2W), DMN-SeVE (2W), SeVE (2W), DMN (6W), DMN-SeVE (6W) and SeVE (6W) treated groups. Hepatocarcinogenesis was induced by ip administration of DMN at 4 mg/kg twice a week for 2 or 6 weeks. Isoenzyme patterns and activities were determined by polyacrylamide gel electrophoresis (PAGE); fractional isoenzyme activities were calculated as percentage of total enzyme activity. DMN treatment for 2 or 6 weeks induced marked changes in the isoenzyme patterns of all investigated hepatic enzymes, which have been compensated to different degrees by combined selenium and vitamin E supplementation especially after 6 weeks. In addition, DMN treatment for 6 weeks induced a significant elevation in total hepatic activity of AST, ALP, LDH and EST. Fractional isoenzyme activities exhibited almost the same trend. In case of ALP, none of the specific isoenzyme activities has significantly changed due to DMN treatment. Isoenzyme activities of AST1, LDH2, LDH5, EST1, EST3, EST5, and EST7 were feasible to differentiate between the effect of DMN and the protective role of combined antioxidant administration. Combined selenium and vitamin E supplementation proved a considerable ability to counteract some but not all DMN-induced changes in total or iosenzyme activities of measured hepatic enzymes. The present investigation came to the conclusion that specific iosenzyme activities could help as additional diagnostic markers during early stages of carcinogenesis.
Key words: : isoenzyme pattern, isoenzyme activity, oxidative stress, hepatocarcinogenesis, dimethylnitosamine, hepatic enzymes, selenium and vitamin E.
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