Large-scale gene profiling of the liver in a mouse model of chronic, intragastric ethanol infusion
Introduction
The mechanisms underlying alcoholic liver disease remain poorly understood. Analysis of fluctuations in the expression of a large spectrum of genes may provide important information on the disease mechanisms. Alcoholic liver disease is essentially a multifactorial disease and has been shown to be associated with changes in gene expression covering a wide spectrum of cellular functions. Thus, changes in liver transcriptome involved in alcohol metabolism [1], [2], cell signaling [3], [4], [5], apoptosis [6], [7], [8], [9], [10], [11], extracellular matrix component metabolism [12], [13], [14], cytokine synthesis (for a review see Ref. [15]), glutathione metabolism [16], oncogenes [17] and other cellular processes have been demonstrated. Although important, the information provided by these studies is limited when compared to what can be achieved with regard to gene expression assessment by using DNA microarray technology. The latter allows simultaneous assessment of expression of a large number of genes, thus providing an unprecedented amount of information. Such data can then be used to explore underlying pathophysiological mechanisms and to generate working hypotheses. This technology has already been used in a number of studies in hepatology and provided important information [18], [19], [20], [21], [22] (for a review see also Ref. [23]). Profiling of gene expression in alcoholic liver disease will provide further insights into disease mechanisms and will open new avenues for discovery of novel therapeutic means. We therefore applied microarray gene technology in this study to analyze gene expression in the livers of mice chronically fed alcohol.
Section snippets
Animal treatment
Throughout the experimental protocols of this study the animals were treated in accordance with the Guide for Care and Use of Laboratory Animals (National Research Council, 1985) approved by the Institutional Animal Care and Use Committee of the Keck School of Medicine of the University of Southern California (Los Angeles, CA). The surgery for intragastric liquid diet infusion and the chronic administration of the diet were performed at the Research Center for Alcoholic Liver and Pancreatic
Plasma ALT activity
Alcohol feeding increased in plasma ALT to 117.9±2.8 mU·ml−1 as compared to pair-fed mice (16.7±2.8 same units; n=5 in each group; P<0.05).
Plasma ethanol levels
At the killing, the plasma ethanol levels were 34.1±0.8 mM.
Histologic appearance of the liver
Alcohol-fed mice displayed lipid accumulation estimated at a score of 3.9±0.6 (see [25] for the significance of this value) and occurrence of necrotic foci covering 13±3% of low magnification (100×) field area, with occasional polymorphonuclear infiltration (Fig. 1A and B).
Gene expression
Gene expression data are
Discussion
We selected the intragastric infusion model because, unlike other animal models of alcohol administration, it allows for high blood alcohol levels (34 mM or 0.16%) which can be frequently encountered in heavy human drinkers during and after repeated drinking episodes. This model induces liver injury which resembles that seen in human alcoholic liver disease, namely fat accumulation, occasional polymorphonuclear infiltration and inflammation and necrosis [28]. The liver appearance observed in
Acknowledgements
This study was supported by NIAAA AA grants nos. 12314 (IVD), 00292 and 12774 (WJSdV), and in part by Research Center for Alcoholic Liver and Pancreatic Diseases—Animal Core of Keck School of Medicine of the University of Southern California, Los Angeles, CA 90089 (P50 AA11999), funded by NIAAA. This material is also the result of work supported with resources and the use of facilities at the Lexington Veterans Administration Center, KY 40536.
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