Authors: Nuriye METE, Birgül IŞIK, Levent ERDİNÇ, Fuat GÜRKAN
Abstract: The question how fish oil (FO) and soybean oil (SO) change the state of antioxidant and the lipid peroxidation in liver and plasma of rats and the protective role of vitamin E were investigated. Six-week-old forty male Sprague-Dawley rats were divided into five groups. One of the groups fed a control diet, another one fed SO, while the other three groups fed FO diet at the level of 10% Vitamin E supplementation was maintained to three different levels 3, 50, 150 IU/per kg diet in the FO diets and 3 IU vitamin E per kg of the SO diet. At the end of tenth week, blood was drawn under ether anesthesia and finally plasma and red blood cell samples were separated. Liver tissues were washed by 0.9% NaCl, then dried by a filter paper and stored at -60oC. The malondialdehyde (MDA) amount as an indicator of lipid peroxidation was not significantly affected in the SO group, while it was found increased both in serum and liver tissue in the FO group with vitamin E supplementation of 3 IU/kg diet (P<0.001). Erythrocyte GSH levels and liver GSH-Px activity were not significantly different between the SO and the control group, while there were significant differences in the FO group with the lowest dose of vitamin E (p<0.001). Catalase activity was not statistically different between groups. MDA production decreased and the antioxidant status was improved by higher doses of vitamin E fed together with FO. A statistically significant positive correlation was found between dietary vitamin E and plasma vitamin C, erythrocyte GSH and liver GSH-Px (P<0.01). In conclusion decreased antioxidant defence and increased MDA amount in the FO fed rats changed to normal with vitamin E supplementation. As significant correlations were found between vitamin E and other antioxidants, vitamin E seems necessary to maintain appropriate levels of other physiological antioxidants.
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