Effects of polyunsaturated/saturated fatty acid ratio and antioxidant supplementation on hepatic TBARS and enzyme activities under the maintenance of dietary peroxidizability index value in young and adult rats

AIMS: To investigate the effects of the polyunsaturated/saturated fatty acid (P/S) ratio and antioxidant supplementation on hepatic lipid peroxidation and enzyme activities under the control of the dietary peroxidizability index (PI) value in young and adult rats. METHODS: We measured thiobarbituric acid-reactive substance (TBARS) concentration and enzyme activities in liver tissue. Female Sprague-Dawley rats aged 3 and 16 weeks were used. Dietary P/S ratios were 0.38 and 4.81 (LP and HP) when the PI value was 81.22. The diets were supplemented with vitamin E 1,000 mg/kg diet and selenium 2.5 mg/kg diet (LPS and HPS). RESULTS: The hepatic TBARS concentration was higher in LP and LPS than in HP and HPS. In reducing TBARS concentration, antioxidant supplementation was more effective in adult rats than in young rats. Glutathione peroxidase and glutathione-S-transferase activities were lower in young rats than in adult rats. CONCLUSION: We conclude that dietary fats and antioxidant supplementation play an important role in the change of hepatic TBARS concentration when the dietary PI value is maintained at the same level. However, with the exception of glutathione reductase, no effects of the P/S ratio and antioxidant supplementation on hepatic enzyme activities were detected. This may be due to the invisible effects of fixed PI value in diets.