Effects of saturated, ω-6 and ω-3 lipids on activities of enzymes involved in antioxidant defense in normal rats

Questions remain as to what types of dietary lipids are most beneficial in enhancing activities of antioxidant defense enzymes and whether changes in unsaturation index of dietary lipids affects the efficiency of antioxidant defense system. The present study was undertaken to determine whether the protective action of omega-3 lipids is through their influence on the antioxidant defense system. Weanling male Sprague Dawley rats were fed semi-purified diets containing 14% fat of either beef fat (BF), safflower oil (SFO) or fish oil (FO) for 7 wks. The effects of dietary lipids on the activities of key enzymes involved in antioxidant defense, catalase, superoxide dismutase (SOD) and glutathione peroxidase (GSH-Px) in rat hepatic cytosolic fractions were examined. Results showed that dietary lipids had a significant effect (p < 0.014) on the activity of GSH-Px. GSH-Px activity was significantly higher in SFO compared to the BF group (p < 0.005) and the FO group (p < 0.04). SOD activity was significantly higher in SFO compared to BF (SFO Vs BF: p < 0.028) and FO group (SFO Vs FO: p < 0.04). Feeding omega-3 fatty acids resulted in higher catalase activity in the FO group though this effect was not statistically significant. These findings suggest that dietary lipids have an impact on the activity of cytosolic antioxidant defense enzymes in rats providing more evidence for one of the mechanisms through which lipids may modulate disease involving antioxidant defense system. (C) 1998 Elsevier Science inc.