We previously reported that ethanol elicits an increased protein oxidation in the liver of rats receiving chronic ethanol by continuous intragastric infusion (TsukamotoFrench method). This accumulation of oxidized proteins could result from a decrease in the cytosolic proteolysis, related specifically to alkaline protease and its major components, the proteasomes. Because several studies suggest that intracellular proteolysis depends on the severity of oxidative stress, we investigated the cytosolic proteolytic activity under two chronic ethanol treatment paradigms associated with varying degrees of oxidative stress.

Our study, for the first time, provided the evidence that acetaldehyde by itself inhibits proteasome activities. As the chronic inhalation model used in this study is not associated with an overt lipid peroxidation, one can suggest that high BALs and their subsequent high acetaldehyde fluxes contribute to impairment of proteasome function and accumulation of carbonylated proteins. This early phenomenon may have relevance in experimental alcohol liver disease.