Drug-primed mice, created by a 5-month feeding of diethyl-1,4-dihydro-2,4,6-trimethyl-3,5-pyridinedicarboxylate (DDC), followed by a 1-month withdrawal, were refed ethanol or isocaloric dextrose (control) diets intragastrically for 7 days. The formation of Mallory bodies (MBs) was monitored by immunofluorescence and immunoperoxidase microscopy using antibodies to cytokeratin and ubiquitin, and also by electron microscopy. The changes in cytokeratin 55 (CK55), ubiquitin conjugate, nuclear factor B (NFB) p65, NFB p50, inhibitor B␣, c-myc, tumor necrosis factor ␣, and cytochrome P450 2E1 (CYP2E1) contents were determined by Western blotting using appropriate antibodies. The messenger RNA (mRNA) for CYP2E1, cytokeratin, ubiquitin, hepatocyte growth factor activator, and tissue transglutaminase was quantitated. MBs were present at 5 to 7 days' postfeeding with ethanol, but not with dextrose. They developed in clusters of ''empty hepatocytes,'' where the cytokeratin antibody failed to recognize the typical filament structures seen in normal hepatocytes. MBs were larger and more numerous in the subcapsular region. Northern blots showed that CK55 mRNA was decreased by the ethanol treatment, but protein levels were increased, suggesting a decreased turnover of the cytokeratin. Likewise, the increase in CYP2E1 protein in the face of a lack of an increase in mRNA for CYP2E1 could be explained by a decreased turnover of this cytochrome. This is the first report of MB formation induced by ethanol ingestion in an experimental model. (HEPATOLOGY 1998;27:116-122.)The association between alcohol abuse and Mallory body (MB) formation in liver goes back to Mallory' s first report in 1911. 1 Mouse is the only species other than man in which MBs can be induced in response to a continuous feeding of various agents like griseofulvin and diethyl-1,4-dihydro-2,4,6-trimethyl-3,5-pyridinedicarboxylate (DDC). However, attempts to induce MBs by ethanol feeding in mice have been as yet unsuccessful, perhaps because of inappropriate experimental conditions. In recent years, we set up a drug-primed mouse model to study MB formation that involved a first feeding of the drug (griseofulvin or DDC) for 5 months, followed by drug withdrawal for 1 month, and a 7-day drug refeeding. [2][3][4] Most of the MBs disappear after the drug withdrawal, leaving only small dot-like MBs at the hepatocyte periphery. However, while it takes at least 3 months of continuous drug feeding before MBs appear in naive mice, 3,4 MBs reappear after only 3 days of refeeding in drug-primed mice. We have used this mouse model to show that heat shock performed in vivo leads to MB formation. 5 Therefore, it was of major interest to determine the response of these drug-primed mice to ethanol feeding. The experimental protocol included feeding via an intragastric indwelling tube to achieve good nutrition and to maintain high blood alcohol levels. 6 The results show for the first time that alcohol ''abuse'' can induce MBs in mice in a few days using a drug-primed model.
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