Metabolomic profiling of a modified alcohol liquid diet model for liver injury in the mouse uncovers new markers of disease

Abstract

Metabolomic evaluation of urine and liver was conducted to assess the biochemical changes that occur as a result of alcohol-induced liver injury. Male C57BL/6J mice were fed an isocaloric control-or alcohol-containing liquid diet with 35% of calories from corn oil, 18% protein and 47% carbohydrate/alcohol for up to 36 days ad libitum. Alcohol treatment was initiated at 7 g/kg/day and gradually reached a final dose of 21 g/kg/day. Urine samples were collected at 22, 30 and 36 days and in additional treatment groups, liver and serum samples were harvested at 28 days. Steatohepatitis was induced in the alcohol-fed group since a 5-fold increase in serum alanine aminotransferase activity, a 6-fold increase in liver injury score (necrosis, inflammation and steatosis) and an increase in lipid peroxidation in liver were observed. Liver and urine samples were analyzed by nuclear magnetic resonance spectroscopy and electrospray infusion/Fourier transform ion cyclotron resonance-mass spectrometry. In livers of alcohol-treated mice the following changes were noted. Hypoxia and glycolysis were activated as evidenced by elevated levels of alanine and lactate. Tyrosine, which is required for L-DOPA and dopamine as well as thyroid hormones, was elevated possibly reflecting alterations of basal metabolism by alcohol. A 4-fold increase in the prostacyclin inhibitor 7,10,13,16-docosatetraenoic acid, a molecule important for regulation of platelet formation and blood clotting, may explain why chronic drinking causes serious bleeding problems. Metabolomic analysis of the urine revealed that alcohol treatment leads to decreased excretion of taurine, a metabolite of glutathione, and an increase in lactate, n-acetylglutamine and n-acetylglycine. Changes in the latter two metabolites suggest an inhibition of the kidney enzyme aminoacylase I and may be useful as markers for alcohol consumption.

Application of GC/MS-based metabonomic profiling in studying the lipid-regulating effects of Ginkgo biloba extract on diet-induced hyperlipidemia in rats

“…This explains the fact that acetic acid levels were increased in the diet-induced hyperlipidemia group. In addition, the acetate level was high in the diet-induced hyperlipidemia group, which suggested a decrease in its metabolism to acetyl-CoA [73] . Acetate is also produced from glycerolphospholipid and pyruvate metabolism [73] .…”

“…In addition, the acetate level was high in the diet-induced hyperlipidemia group, which suggested a decrease in its metabolism to acetyl-CoA [73] . Acetate is also produced from glycerolphospholipid and pyruvate metabolism [73] . This might cause decreased levels of threonine and glycine in the diet-induced hyperlipidemia group.…”

An optimized procedure for metabonomic analysis of rat liver tissue using gas chromatography/time-of-flight mass spectrometry

“…Therefore, tissue-targeted technology has considerable value since many diseases may cause detectable disturbances only to the local metabolic pathways within specific organs [11]. Tissue-targeted metabonomic analyses have been carried out on brain tissue [11][12][13], liver tissue [14][15][16], and kidney tissue [17][18][19]. Metabolite extraction is a critical step in tissue metabonomic study, and the chloroform-methanol-water solvent system is considered the preferred method in several reports [20][21][22][23].…”

Identification of N-Acetyltaurine as a Novel Metabolite of Ethanol through Metabolomics-guided Biochemical Analysis

“…Recent arrival of metabolomics, a global system biology methodology for measuring small molecule metabolite profiles and fluxes in biological matrices (35), offers a new and powerful tool to characterize the metabolic changes induced by ethanol and to identify the small molecule biomarkers of ethanol-induced toxicities. Mass spectrometry (MS)-based and nuclear magnetic resonance (NMR)-based metabolomic analyses of urine, blood, and tissue samples have revealed the changes of organic acids (36), amino acids (37), and their derivatives (38), as well as fatty acids and associated lipid species (39) in the biofluids following ethanol treatment.…”