The response of rats to long-term feeding with diets containing oxidized fat. 2. Biochemical indicators in the serum, liver, and bone mineralization

Selected biochemical indicators in blood and liver and indicators of femur mineralization were determined in rats fed for eight weeks on diets contain ing 10% fat with a peroxide value below 5, 40, 80, 120, 160, or 200 meg O-2 /kg. The average body weight of the rats was 259.9+/-10.5 g, the experiment al groups contained 12 animals. Fat with a high peroxide value (160 and 200 meg O-2/kg) significantly increased the concentration of malondialdehyde i n the serum and slightly in the liver. The most sensitive indicators of the reaction of rats to oxidation of dietary fat were the activity of glutathi one peroxidase in erythrocytes, which increased with the rising degree of d ietary fat oxidation, i.e. at 40 meg O-2/kg, the activity of serum aspartat e aminotransferase and the vitamin A content in the liver, which fell at a peroxide value of 80 meg O-2/kg. A less sensitive indicator was erythrocyte peroxide dismutase activity, which did not increase until fat with a perox ide value of 160 meg O-2/kg was fed. The degree of fat oxidation did not si gnificantly affect the activity of serum alanine aminotransferase, liver en zymes (aspartate aminotransferase, alanine aminotransferase, acid phosphata se, and lactate dehydrogenase), serum and liver triglycerides levels, total cholesterol and HDL cholesterol, or femur mineralization indicators.