Lipid peroxidation and glutathione peroxidase activity in the liver of cholesterol-fed rats.

The effects of cholesterol feeding on lipid peroxidation and on glutathione peroxidase activity in the liver of rats were examined. Cholesterol (1 or 1.5%) was added to two basal diets containing either 10% soy oil (diet 1) or 15% soy oil plus 100 IU of alpha-tocopherol/kg of diet (diet 2). The rate of lipid peroxidation in the liver was determined in vitro by the thiobarbituric acid test and by conjugated diene measurement (234 nm). Cholesterol feeding elevated the rate of lipid peroxidation in the liver of rats fed diet 1 or 2. The rate of lipid peroxidation in rats fed diet 2 increased with duration of feeding suggesting an increased need for antioxidant as the levels of cholesterol or other lipids in the liver elevated. Cholesterol feeding also decreased the activity of liver glutathione peroxidase and pentose phosphate pathway dehydrogenases. Glutathione peroxidase activities increased with the duration of feeding in rats fed basal diet 2, but they remained unchanged in rats fed the same diet supplemented with cholesterol. The study suggests that cholesterol feeding in rats can increase the susceptibility of the tissue to lipid peroxidation and also can lead to a depression in the activity of glutathione peroxidase.