Detection and localization of protein-acetaldehyde adducts in rat brain after chronic ethanol treatment

BACKGROUND: Ethanol is metabolized to acetaldehyde in the cell, which is potentially deleterious because it can react with cellular proteins and form protein-acetaldehyde adducts, which can interfere with normal cellular function. Because the primary site of ethanol action is the brain, the present study was carried out to determine whether protein-acetaldehyde adducts are formed in rat brain after chronic ethanol administration. METHODS: Rats were treated with ethanol for 1 year, and the formation of protein-acetaldehyde adducts was examined by immunoblot analysis and localized in brain by immunohistochemical analysis by using affinity purified antibody to acetaldehyde-hemocyanin adduct. RESULTS: In the brain of rats administered ethanol for up to 1 year, protein-acetaldehyde adducts were detectable by immunoblot analysis. In brain, mitochondria was the primary site of adduct formation, unlike the liver, where the major protein-acetaldehyde adduct has been detected in the cytosol. Immunohistochemical localization of protein-acetaldehyde adducts in chronic ethanol-treated rat brain demonstrated the selective presence of adducts in cortical neurons, granule cell layer of dentate gyrus, neurons in the midbrain, and granular cell layers of cerebellum. CONCLUSIONS: These results demonstrate the significant formation of protein-acetaldehyde adducts in rat brain after ethanol ingestion. The modification of mitochondrial proteins in brain by protein-acetaldehyde adduct formation is significant because mitochondrial dysfunction has been implicated in neurodegeneration.