ACETALDEHYDE-MODIFIED AND 4-HYDROXYNONENAL-MODIFIED PROTEINS IN THE LIVERS OF RATS WITH ALCOHOLIC LIVER-DISEASE

Liver proteins form adducts with acetaldehyde and are modified by prod ucts of lipid peroxidation in alcohol-fed animals, It has been hypothe sized that the formation of these modified liver proteins may contribu te to liver injury in alcoholic liver disease, The present work was pe rformed to determine the extent of protein modification in rats with e xperimental alcoholic liver disease, Rats were fed ethanol intragastri cally with medium chain triglycerides (MCTs), palm oil, corn oil, or f ish oil, The group fed MCTs and ethanol showed no liver injury, rats f ed palm oil and ethanol showed only fatty liver, rats fed corn oil and ethanol showed fatty liver with moderate necrosis and inflammation, a nd rats fed fish oil and ethanol showed fatty liver with severe necros is and inflammation. Antibodies were raised by using keyhole limpet he mocyanin modified in vitro by 4-hydroxynonenal (4-HNE) or acetaldehyde as immunogens. When liver extracts were examined by Western blot anal ysis, the intensities of the acetaldehyde-modified protein band (37 kd ) in the alcohol-fed animals were significantly different among the et hanol-treated groups and correlated with plasma acetaldehyde concentra tions, It was strongest in rats fed fish oil and ethanol, followed by rats fed paint oil and ethanol and rats fed corn oil and ethanol, wher eas rats fed MCTs and ethanol showed the weakest intensity. The 37-kd protein-adetaldehyde adduct was located mainly in the pericentral regi on of the liver, No acetaldehyde adduct was detected in the control ra ts that were pair-fed with isocaloric amounts of dextrose, Western blo t analysis using the anti-4-HNE antibody showed four distinctive bands (48, 45, 40, and 38 kd) in the liver extracts of alcohol-fed rats. Co ntrol animals showed only a weak 38-kd band, Although the intensities of the 48-, 40-, and 38-kd bands were similar among the different etha nol-treated groups, the intensity of the 45-kd band decreased from MCT s and ethanol > palm oil and ethanol greater than or equal to corn oil and ethanol > fish oil and ethanol, The data indicate that the degree of liver protein modification by acetaldehyde correlates well with th e severity of liver injury in ethanol-fed rats, whereas modification b y the lipid peroxidation product 4-HNE shows no correlation with the s everity of liver injury.