Elsevier

Journal of Hepatology

Volume 40, Issue 2, February 2004, Pages 219-227
Journal of Hepatology

Large-scale gene profiling of the liver in a mouse model of chronic, intragastric ethanol infusion

https://doi.org/10.1016/j.jhep.2003.10.021Get rights and content

Abstract

Background/Aims: The mechanisms underlying alcohol-induced liver injury are not fully elucidated. An approach in this direction would consist of an all-inclusive assessment of gene expression in the liver. The purpose of this study was to perform a comprehensive analysis of gene expression in the livers of mice treated with ethanol by means of intragastric infusion.

Methods: An ethanol- or glucose-enriched liquid diet was fed to animals for 4 weeks via a long-term gastrostomy catheter. The animals were killed and plasma alanine:2-oxoglutarate aminotransferase (ALT) assay, liver histology and total RNA analysis by microarray gene technology were performed.

Results: Alcohol increased ALT, induced steatosis, necrosis and inflammation. A total of 12,423 genes were analyzed for expression out of which 4867 were expressed by the liver. Alcohol repressed expression of 11 genes, induced expression of 13 genes, and up- or down-regulated expression of 44 and 42 genes >2-fold, respectively. Gene expression analysis identified several genes that have not previously been tested for alcohol effects.

Conclusions: This study: (i) expands the knowledge of mechanism(s) of action of ethanol; (ii) indicates novel pathways of ethanol action on the liver, and (iii) illustrates the utility of microarray gene analysis in hepatology research.

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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