Activities of antioxidant enzymes induced by ethanol exposure in Aldehyde dehydrogenase 2 knockout mice

Acetaldehyde production during ethanol metabolism has been implicated as an important link between oxidative stress and cell damage, which suggests that oxidative stress caused by ethanol exposure may be more severe in aldehyde dehydrogenase 2 (ALDH2)-deficient individuals than in those with wild-type ALDH2. We evaluated the activities of the major antioxidant enzymes, superoxide dismutase (SOD), catalase (CAT), and glutathione peroxidase (GPx), in liver tissue isolated from Aldh2 +/+ and Aldh2 -/- mice that were exposed to ethanol. The activities of CAT and GPx were significantly increased by ethanol treatment in A1dh2 +/+ mice (3.33-fold and 1.65-fold, respectively). The mean activity of SOD in A1dh2 +/+ mice was 1.46-fold that in the A1dh2 +/+ control group, but the difference was not statistically significant. In Aldh2 -/- mice, the activities of SOD and CAT were decreased and that of GPx was slightly increased after ethanol exposure, but the differences were not significant. We postulate that antioxidant enzyme expression after ethanol consumption may differ according to the intracellular level of acetaldehyde or free radicals, which in turn depends on the activity of ALDH2. These results suggest that the greater toxicity of ethanol in Aldh2 -/- mice than in Aldh2 +/+ mice may be due to decreased antioxidant enzyme expression.