Changes in Activity of the Manganese Superoxide Dismutase Enzyme in Tissues of the Rat with Changes in Dietary Manganese

Abstract

The effects of dietary manganese deficiency on the activity of the manganese-containing superoxide dismutase enzyme (Mn SOD, EC 1.15.1.1) in tissues of the rat were investigated and compared to changes in the activity of two manganese-activated enzymes and in tissue manganese concentrations. Weanling male rats were fed diets containing 0.2 (basal), 0.7, 1.7, 4.7, 9.7 or 29.7 mg Mn/kg, for 10 weeks. In both heart and kidney, Mn SOD activity was significantly depressed by decreased dietary manganese; greatest reduction occurred in the heart. Relative decreases in heart Mn SOD activity were apparent 3 weeks after feeding of the diets commenced; decreases in kidney activities were not apparent until 6 weeks. After feeding the diets for 10 weeks, significant correlations of dietary manganese concentration were observed with heart and kidney Mn SOD activities, liver arginase and plasma alkaline phosphatase activities, and heart, kidney, liver and plasma manganese concentrations. A minimal dietary manganese concentration of 2 to 4 mg Mn/kg was required for near maximal growth and near maximal activity of Mn SOD in heart and kidney tissue. With manganese depletion, no significant changes occurred in the activities of either the copper-containing superoxide dismutase enzyme, or glutathione peroxidase, in any of the tissues examined.