EFFECT OF FATTY-ACID COMPOSITION, CADMIUM AND VITAMIN-E INTAKE ON PROOXIDATIVE-ANTIOXIDATIVE STATE OF RAT-LIVER

The effect of cadmium intake (100 mu g/kg body weight/day as cadmium chloride over a period of three months) on the prooxidative-antioxidative state of liver was studied in 30 days old weaned male rats. Animals were fed a nutritionally balanced lacto-vegetable diet containing high-quality amino acid mixture (casein + gluten 1:1), lipids in form of either pork fat PF (% of polyunsaturated fatty acids PUFA = 11.9; unsaturation index UI = 72), margarine MA (% PUFA = 21.9; UI = 98), or soybean oil SO (% PUFA = 61.2; UI = 156) and vitamin E at amount of 60 mg/kg of food (groups PF, PF + Cd, MA, MA + Cd, SO, SO + Cd) or 600 mg (groups PF + Cd + E, MA + Cd + E, SO + Cd + E) in form of alpha-tocopheryl acetate. The following parameters were measured: conjugated dienes of fatty acids (CD), activities of superoxide dismutase (SOD), catalase (CAT) (as relative generation of H2O2) and glutathione peroxidase (GSH-Px). A direct relation between lipoperoxidation values and unsaturation index of lipids was found both in spontaneous (PF, MA, SO - control) and cadmium-induced generation of free oxygen radicals. Cadmium intake resulted in a disbalance in prooxidative-antioxidative processes which was manifested in a significant increase of CD in all fat sources (the degree of increase was directly proportional to UI and PUFA), in similar values of relative H2O2 generation and in a nonsignificant increase of GSH-Px in animals with most developed lipo peroxidation (SO). A tenfold increase in the administered dose of vitamin E restored a prooxidative-antioxidative equilibrium disturbed by cadmium intake in the liver of rats fed the diet with animal fat (PF + Cd + E) and margarine (MA + Cd + E) (reduction of CD to the level of control groups, decrease of relative generation of H2O2 - significant in MA). In animals fed with soybean oil, a vitamin E - induced reduction of CD was significantly over the control level simultaneously with significant stimulation of GSH-Px activity. No changes in H2O2 generation together with CD levels and GSH-Px activity indicated that a synergic effect of several antioxidants is essential in the case of high lipoperoxidation. Presented results are important with respect to possible control or regulation of the equilibrium between prooxidative and antioxidative processes by nutrition.