The effect of dietary-induced obesity on lipid peroxidation, antioxidant enzymes and total plasma antioxidant capacity.

The aim of this study was to examine the effect of dietary-induced obesity on some parameters of oxidative stress and antioxidant defence. The studies were performed in adult male Wistar rats. Control group received normal laboratory chow (62% calories as carbohydrates, 26% protein and 12% fat). High-calorie high-fat group (HCHF) was fed standard chow supplemented with lard (48% calories as carbohydrates, 20% as protein and 32% as fat) and high-calorie normal-fat group (HCNF) received standard chow and liquid diet containing sucrose, glucose, whole milk powder and soybean powder (60% carbohydrates, 26% protein, 14% fat). After 8 weeks body weight of HCHF and HCNF-fed rats was higher than body weight of controls by 9.3% and 15.2%, respectively. Plasma concentration of thiobarbituric acid-reactive substances (TBARS) increased in these groups by 43% and 52%, respectively. The activity of superoxide dismutase (SOD) decreased in HCHF group by 47.5% and in HCNF group by 21.1%. Glutathione peroxidase (GPx) activity in the blood tended to increase in both experimental groups but this was not significant. Plasma total antioxidant status (TAS) measuring the combined free radicals scavenging ability of nonenzymatic antioxidants was lower in HCHF and in HCNF group compared to control (-8.8% and -9%, respectively). The major observed lipid abnormalities were hypertriglyceridemia in HCHF group and decreased HDL-cholesterol in HCNF group. TBARS correlated negatively with SOD (r = -0.84, p < 0.001) and with TAS (r = -0.47, p < 0.05). These results indicate that obesity leads to oxidative stress which can contribute to obesity-associated diseases such as atherosclerosis, diabetes mellitus and arterial hypertension.