Author
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SAMPEY, BRANTE - UNIV. OF COLORADO |
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KOROURIAN, SOHEILA - UAMS |
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RONIS, MARTIN - UAMS |
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BADGER, THOMAS - UAMS |
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PETERSEN, DENNIS - UNIV. OF COLORADO |
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Submitted to: Alcoholism: Clinical and Experimental
Publication Type: Peer Reviewed Journal Publication Acceptance Date: 3/24/2003 Publication Date: 6/13/2003 Citation: SAMPEY, B.P., KOROURIAN, S., RONIS, M.J., BADGER, T.M., PETERSEN, D.R. IMMUNOHISTOCHEMICAL CHARACTERIZATION OF HEPATIC MALONDIALDEHYDE AND 4-HYDROXYNONENAL MODIFIED PROTEINS DURING EARLY STAGES OF ETHANOL-INDUCED LIVER INJURY. ALCOHOLISM: CLINICAL AND EXPERIMENTAL RESEARCH. 2003. v. 27(6). p. 1015-1022. Interpretive Summary: Low levels of alcohol consumption can be healthful, while higher levels can have adverse effects. Alcohols are dietary sources of energy and there is a controversy as to whether ethanol is metabolized as a fat or a carbohydrate. We have studied the health effects of alcohol consumption in rats fed by total enteral nutrition to determine the relative effects of diet factors on the actions of ethanol. In this study we found that higher levels of ethanol intake with a diet made from low carbohydrate and high fat plus adequate protein, vitamins and minerals, increases peroxidation of lipids. This is associated with advise effects on tissues and results in inflammation and could lead to fibrosis. These results provide important insights into the actions of ethanol and are now being applied to our studies on the effects of alcohol intake during pregnancy on both the mother and the offspring. Technical Abstract: Background: Chronic ethanol consumption is associated with hepatic lipid peroxidation and the deposition or retention of aldehyde-adducted proteins postulated to be involved in alcohol-induced liver injury. The purpose of this study was to characterize hepatocellular formation of aldehyde-protein adducts during early stages of alcohol-induced liver injury. Methods: Female Sprague Dawley rats were subjected to the intragastric administration of a low-carbohydrate/high-fat total enteral nutrition diet or a total enteral nutrition diet containing ethanol for a period of 36 days. Indexes of hepatic responses to ethanol were evaluated in terms of changes in plasma alanine aminotransferase activity, hepatic histopathologic analysis, and induction of cytochrome P-4502E1 (CYP2E1). Immunohistochemical methods were used to detect hepatic proteins modified with malondialdehyde (MDA) or 4-hydroxynonenal (4-HNE) for subsequent quantitative image analysis. Results: After 36 days of treatment, rats receiving the alcohol-containing diet displayed hepatic histopathologies characterized by marked micro- and macrosteatosis associated with only minor inflammation and necrosis. Alcohol administration resulted in a 3-fold elevation of plasma alanine aminotransferase activity and 3-fold increases (p less than 0.01) in hepatic CYP2E1 apoprotein and activity. Quantitative immunohistochemical analysis revealed significant (p less than 0.01) 5-fold increases in MDA- and 4-HNE modified proteins in liver sections prepared from rats treated with alcohol. The MDA- or 4-HNE modified proteins were contained in hepatocytes displaying intact morphology and were colocalized primarily with microvesicular deposits of lipid. Aldehyde-modified proteins were not prevalent in parenchymal or nonparenchymal cells associated with foci of necrosis or inflammation. Conclusions: These results suggest that alcohol-induced lipid peroxidation is an early event during alcohol-mediated liver injury and may be a sensitizing event resulting in the production of bioactive aldehydes that have the potential to initiate or propagate ensuing proinflammatory or profibrogenic cellular events. Key Words: Lipid Peroxidation; Aldehyde-Modified Proteins; Liver Injury; Malondialdehyde; 4-Hydroxynonenal; Immunohistochemistry |
