Relationship between dietary retinol and alpha-tocopherol and lipid peroxidation in rat liver cytosol

The effects of retinol and alpha-tocopherol-deficient and supplemented diets on the cytosolic concentration of thiobarbituric acid reactive substances (TBARS) in rat liver have been studied. Physiological lipoperoxidation (LPO) was observed in liver cytosol of control rats (TBARS = 0.315 +/- 0.034 nmol of MDA equivalents/mg of liver cytosolic proteins). In retinol-deficient diets there was a decrease in retinolaemia and the absence of retinol in liver cytosol while cytosolic TBARS increased significantly (P less than 0.001). Vitamin E was not found in cytosolic fractions, except in alpha-tocopherol-supplemented diet rats. alpha-Tocopherol-deficient diets induced an absence of vitamin E in the serum and cytosolic TBARS were increased compared to controls (P less than 0.001). Supplementation of the diet with retinol and alpha-tocopherol or both in combination induced a significant decrease in liver cytosolic TBARS (P less than 0.001). Finally the combination of low dietary supplementation with retinol and alpha-tocopherol (ten times the normal diet each) induced the maximum anti-LPO effect.