Superoxide dismutase activity and lipid peroxidation in the rat: Developmental correlations affected by manganese deficiency

The activities of the mitochondrial enzyme manganese-superoxide dismutase (MnSOD), the cytosolic enzyme copper-zinc superoxide dismutase (CuZnSOD), and lipid peroxidation in liver were measured in manganese-sufficient and manganese-deficient rats from birth to 60 days of age. In both groups of rats there was an increase in MnSOD activity during development. In control rats MnSOD activity increased over sixfold between day 1 and day 60. However, in manganese-deficient animals the activity of this enzyme increased only threefold during this time period. In both groups of rats there was approximately a sixfold increase in CuZnSOD activity between day 1 and day 60. After day 10, CuZnSOD activity tended to be higher in Mn-deficient rats, with this difference being significant on day 15 (P > 0.01). Measurements of thiobarbituric acid-reacting products (TBA index) under conditions of oxidant stress suggested that there was a higher than normal level of mitochondrial lipid peroxidation in manganese-deficient rats by 60 days of age. Lipid peroxidation increased from day 1 to day 60 in both groups of rats, but a fivefold increase occurred in manganese-deficient rats while in controls the increase was only threefold. These findings suggest that the damage to mitochondrial membranes observed in manganese-deficient animals may be due to depressed MnSOD activity resulting in increased lipid peroxidation from free radicals.