Analysis of time-related metabolic fluctuations induced by ethionine in the rat.
ABSTRACT The time-course of metabolic events following response to a model hepatotoxin ethionine (800 mg/kg) was investigated over a 7 day period in rats using high-resolution (1)H NMR spectroscopic analysis of urine and multivariate statistics. Complementary information was obtained by multivariate analysis of (1)H MAS NMR spectra of intact liver and by conventional histopathology and clinical chemistry of blood plasma. (1)H MAS NMR spectra of liver showed toxin-induced lipidosis 24 h postdose consistent with the steatosis observed by histopathology, while hypertaurinuria was suggestive of liver injury. Early biochemical changes in urine included elevation of guanidinoacetate, suggesting impaired methylation reactions. Urinary increases in 5-oxoproline and glycine suggested disruption of the gamma-glutamyl cycle. Signs of ATP depletion together with impairment of the energy metabolism were given from the decreased levels in tricarboxylic acid cycle intermediates, the appearance of ketone bodies in urine, the depletion of hepatic glucose and glycogen, and also hypoglycemia. The observed increase in nicotinuric acid in urine could be an indication of an increase in NAD catabolism, a possible consequence of ATP depletion. Effects on the gut microbiota were suggested by the observed urinary reductions in the microbial metabolites 3-/4-hydroxyphenyl propionic acid, dimethylamine, and tryptamine. At later stages of toxicity, there was evidence of kidney damage, as indicated by the tubular damage observed by histopathology, supported by increased urinary excretion of lactic acid, amino acids, and glucose. These studies have given new insights into mechanisms of ethionine-induced toxicity and show the value of multisystem level data integration in the understanding of experimental models of toxicity or disease.
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ABSTRACT: CCl(4)-induced metabonomic changes have been extensively studied for mammalian liver, and such changes have not been reported for other organs. To investigate the CCl(4) effects on other organs, we analyzed the CCl(4)-induced metabonomic changes in rat kidney, lung, and spleen using (1)H NMR-based metabonomics approaches with complementary information on serum clinical chemistry and histopathology. We found that acute CCl(4) exposure caused significant level elevation for creatine and decline for glucose, taurine, trimethylamine, uridine, and adenosine in rat kidney. CCl(4)-treatment also induced elevation of amino acids (isoleucine, leucine, valine, threonine, alanine, lysine, ornithine, methionine, tyrosine, phenylalanine, and histidine), creatine, and betaine in rat lung together with depletion of glycogen, glucose, taurine, glycine, and hypoxanthine. Furthermore, CCl(4) caused elevation of lactate, alanine, betaine, and uracil in rat spleen accompanied with decline for glucose, choline, and hypoxanthine. These observations indicated that CCl(4) caused oxidative stresses to multiple rat organs and alterations of their functions including renal osmotic regulations, accelerated glycolysis, and protein and nucleotide catabolism. These findings provide essential information on CCl(4) toxicity to multiple rat organs and suggest that systems toxicological views are required for metabonomic studies of toxins by taking many other organs into consideration apart from so-called targeted ones.Journal of Proteome Research 05/2012; 11(7):3848-59. · 5.06 Impact Factor
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ABSTRACT: It is essential that the novel biomarkers discovered by means of advanced detection tools based on metabonomics could be used for long-term monitoring in food safety. By summarizing the common biomarkers discovery flowsheet based on metabonomics, this review evaluates the possible application of metabonomics in new biomarker discovery, especially in relation to food safety issues. Metabonomics have the advantages of decreasing detection limits and constant monitoring. Although metabonomics is still in the developmental stage, we believe that, based on its properties, such as noninvasiveness, sensitivity, and persistence, together with rigorous experimental designs, new and novel technologies, as well as increasingly accurate chemometrics and a relational database, metabonomics can demonstrate extensive application in food safety in the postgenome period.Critical reviews in food science and nutrition 09/2012; 52(9):761-74. · 3.73 Impact Factor
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ABSTRACT: S-adenosylmethionine (AdoMet, also known as SAM and SAMe) is the principal biological methyl donor synthesized in all mammalian cells but most abundantly in the liver. Biosynthesis of AdoMet requires the enzyme methionine adenosyltransferase (MAT). In mammals, two genes, MAT1A that is largely expressed by normal liver and MAT2A that is expressed by all extrahepatic tissues, encode MAT. Patients with chronic liver disease have reduced MAT activity and AdoMet levels. Mice lacking Mat1a have reduced hepatic AdoMet levels and develop oxidative stress, steatohepatitis, and hepatocellular carcinoma (HCC). In these mice, several signaling pathways are abnormal that can contribute to HCC formation. However, injury and HCC also occur if hepatic AdoMet level is excessive chronically. This can result from inactive mutation of the enzyme glycine N-methyltransferase (GNMT). Children with GNMT mutation have elevated liver transaminases, and Gnmt knockout mice develop liver injury, fibrosis, and HCC. Thus a normal hepatic AdoMet level is necessary to maintain liver health and prevent injury and HCC. AdoMet is effective in cholestasis of pregnancy, and its role in other human liver diseases remains to be better defined. In experimental models, it is effective as a chemopreventive agent in HCC and perhaps other forms of cancer as well.Physiological Reviews 10/2012; 92(4):1515-42. · 30.17 Impact Factor