Adrenocortical Expression of MnSOD

Abstract

The mitochondrial matrix antioxidant manganese superoxide dismutase (MnSOD) is part of a cascade of components that protects the cell from cytotoxic reactive oxygen species (ROS) and previous investigations have predominately concentrated on this role. However, recent studies on the roles of redox state and ROS suggest that they may have a role in cellular regulation. Using a cDNA clone we generated, northern blot analysis localised the expression of MnSOD predominantly to the zona fasciculata and reticularis (zfr) in rat adrenals. To test whether this correlated with MnSOD activity, assays were conducted on adrenal tissue from rats maintained on a low sodium diet or betamethasone treated and compared with that of untreated controls. MnSOD activity was enhanced in zfr adrenal mitochondria from rats that were ACTH treated or on a low sodium diet. Betamethasone had no effect, and cytosolic/membrane SOD activities were unchanged by all of the treatments. The identification of MnSOD as a hormone inducible component in the adrenal cortex is consistent with the concept that the redox state and/or ROS are involved in the specific regulation of zfr function.