Superoxide Dismutase Dysregulation Undermines Endogenous Antioxidant System and Promote Retinal Neurodegenerative Pathology

Abstract

Oxidative stress is generally associated with unregulated relationship between free radical production and enzymes responsible for clearing them. Endogenous antioxidant system protects various tissues and cells rendered susceptible to damage by exposure to excessive oxidative milieu. Superoxide dismutase is one of the major enzymes in living systems to regulate endogenous reactive oxygen species (ROS) levels. It partitions highly reactive superoxide radicals into less damaging oxygen or hydrogen peroxide (H2O2). Glutathione peroxidase and catalase are some of the other enzymes which play significant roles in maintaining the equilibrium of free radicals and further decompose H2O2. Catalase mediates decomposition of hydrogen peroxide into O2 and H2O while glutathione peroxidase catalyses reduction of lipid hydroperoxides and hydrogen peroxide to H2O. In the eye, ROS has particularly been implicated in mediating damage to retinal cells and other ocular tissues in diseases such as ocular hypertension, age related macular degeneration (AMD) and various inflammatory disorders of the eye.