Redox modulation of the liver with chronic antioxidant enzyme mimetic treatment prevents age-related oxidative damage associated with environmental stress

A reduction in stress tolerance is a hallmark of the aging process, and the lowered functional capacity observed in aged organisms is associated with an increased rate of oxidative stress and a greater susceptibility of aged tissues to oxidative injury. In this report, we show that chronic systemic administration of a superoxide dismutase (SOD)/catalase mimetic (EUK-189), delivered over a 1 month period via osmotic pump, prevents heat stress-induced liver injury by dramatically decreasing oxidative damage in aged animals. Widespread liver injury was present in old but not young vehicle-treated rats in response to a 2 day heating protocol. However, SOD/catalase mimetic treatment markedly decreased the hyperthermia-induced liver injury associated in old animals. The reversal of damage with EUK-189 was associated with an improvement in intracellular redox status and a striking reduction in hepatocellular lipid peroxidation. EUK-189 treatment also blocked the activation of activator protein-1 (AP-1), which is a redox-sensitive early response transcription factor involved in the regulation of cellular stress responses. These results demonstrate that oxidative stress plays a unique role in age-related hyperthermic injury and suggest that therapeutic strategies aimed at improving redox potential, such as chronic SOD/catalase mimetic treatment, can prevent the oxidative-mediated damage associated with environmental stress.