Nutritional condition affects the hepatic antioxidant systems in steers

The objectives of this study were to evaluate the activity of antioxidant s ystems in the hepatic tissues of steers experimentally subjected to a restr icted diet. Hence, the activities of superoxide dismutase (SOD) and reduced glutathione (GSH) and lipid peroxide levels were measured. Nine male Holst ein steers were used. They were separated in two groups: three steers in gr oup 1 (control) and six steers in group 2, which were subjected to a restri cted diet that covered only 60% of the maintenance requirements. After 30 d ays, the animals in both groups were killed and studies were completed. Bot h the CuZn-SOD and the glucose-6-phosphate dehydrogenase activities were si gnificantly decreased (p <0.05) in group 2, reaching 68% and 60%, respectiv ely, of the concentrations found in group 1. The concentration of GSH in gr oup 2 was 6.71 +/-0.9 nmol/mg protein, which was significantly lower (p <0. 01) than that of the controls, 25.7 +/-2.4 nmol/mg protein. In addition, th e lipid peroxide levels were significantly increased (p <0.01) in group 2, being 50-60% higher than that in group 1. These results showed that the poo r nutritional status caused modifications to the enzymatic antioxidant syst ems, with a lower ability to reduce oxidative compounds and a state of lipi d peroxidation.