Effects of dietary fats (fish, olive and high-oleic-acid sunflower oils) on lipid composition and antioxidant enzymes in rat liver

The effects of two oleic-acid-rich diets (containing olive oil, OO, and hig h-oleic-acid sunflower oil, HOSO) on plasma and liver lipid composition det oxification enzyme activities, were compared with those of a fish-oil (FO) diet and a control diet. Compared with the control diet, plasma and hepatic total triacylglycerol concentrations were increased in the animals fed on the HOSO and OO diets and decreased in those fed on the FO diet. The animal s fed on FO showed the highest level of cholesterol in the liver and had lo wer plasma cholesterol concentrations when compared with those fed on the t wo oleic-acid-rich diets. In comparison with the animals fed on the diets e nriched in oleic acid, the FO group showed higher hepatic levels of polyuns aturated fatty acids of the n-3 series and lower levels of fatty acids of t he n-6 series. Livers of FO-fed rats, compared with those of OO- and HOSO-f ed rats showed: (1) significantly higher activities of catalase (EC 1.11.1. 6) glutathione peroxidase (EC 1.11.1.9) and Cu/Zn superoxide dismutase (EC 1.15.1.1); (2) no differences in the NADPH-cytochrome c reductase (EC 1.6.9 9.3) activity. The HOSO diet had a similar effect on liver antioxidant enzy me activities as the OO diet, in conclusion, it appears that changes in the liver fatty acid composition due mainly to n-3 lipids may enhance the effi ciency of the antioxidant defence system. The two monounsaturated fatty aci ds oils studied (OO and HOSO), with the same high content of oleic acid but different contents of natural antioxidants, had similar effects on the ant ioxidant enzyme activities measured.