NMR and pattern recognition studies on the time-related metabolic effects of alpha-naphthylisothiocyanate on liver, urine, and plasma in the rat: an integrative metabonomic approach

Papaverine attenuates the progression of alpha naphthylisothiocyanate induce cholestasis in rats

Cholestasis is a hepatobiliary condition that manifests as acute or chronic and results from disruptions in the bile flow, formation, or secretion processes. The Farnesoid X receptor (FXR) is a vital target for the therapy of cholestasis since it regulates BA homeostasis. Despite the discovery of multiple active FXR agonists, there are still no effective treatments for cholestasis. Papaverine is identified as an FXR agonist.This study investigates papaverine's efficacy and probable mechanism in protecting against alpha naphthylisothiocyanate (ANIT) induced cholestasis. Thirty male albino rats were divided into three groups, each with ten rats. Group I (control) rats were administered 1 mL/kg corn oil 48 h before sacrifice; group II rats were orally administered 100 mg/kg ANIT. Group III received a 200 mg/kg dosage of papaverine over seven consecutive days. A single dose of ANIT at a concentration of 100 mg/kg was orally administered on the fifth day; group II and III animals were euthanized 48 h after inducing cholestasis, and serum concentrations of liver function tests and total bile acid (TBA) were measured. Besides measuring the inflammatory mediator's tumor necrosis factor-alpha (TNF-α) and interleukin 1 (IL-1β), antioxidant markers such as superoxide dismutase (SOD) and glutathione (GSH) were also assessed. The findings indicated the enhancement in the liver function test and total bile acids, as well as in liver histology; papaverine significantly lowered TNF-α and IL-1β while SOD and GSH significantly increased. Additionally, papaverine upregulates Fxr gene expression, bile salt export pump (Besp), small heterodimer partner (shp), hepatocyte nuclear factor 1α (Hnfα), nuclear factor erythroid 2-related factor (Nrf2), heme oxygenase (Ho-1), NAD(P)H quinone oxidoreductase 1 (Nqo1). Furthermore, papaverine increased protein expressions of Sirtuin1. (SIRT 1), FXR, HO-1, and BSEP levels in the rats' livers. The protective effects of papaverine may be attributed to the activation of FXR signaling pathways. These findings revealed that papaverine protects against ANIT-induced Cholestasis.

Whole-Blood Metabolomics of a Rat Model of Repetitive Concussion

Mild traumatic brain injury (mTBI) and repetitive mTBI (RmTBI) are silent epidemics, and so far, there is no objective diagnosis. The severity of the injury is solely based on the Glasgow Coma Score (GCS) scale. Most patients suffer from one or more behavioral abnormalities, such as headache, amnesia, cognitive decline, disturbed sleep pattern, anxiety, depression, and vision abnormalities. Additionally, most neuroimaging modalities are insensitive to capture structural and functional alterations in the brain, leading to inefficient patient management. Metabolomics is one of the established omics technologies to identify metabolic alterations, mostly in biofluids. NMR-based metabolomics provides quantitative metabolic information with non-destructive and minimal sample preparation. We employed whole-blood NMR analysis to identify metabolic markers using a high-field NMR spectrometer (800 MHz). Our approach involves chemical-free sample pretreatment and minimal sample preparation to obtain a robust whole-blood metabolic profile from a rat model of concussion. A single head injury was given to the mTBI group, and three head injuries to the RmTBI group. We found significant alterations in blood metabolites in both mTBI and RmTBI groups compared with the control, such as alanine, branched amino acid (BAA), adenosine diphosphate/adenosine try phosphate (ADP/ATP), creatine, glucose, pyruvate, and glycerphosphocholine (GPC). Choline was significantly altered only in the mTBI group and formate in the RmTBI group compared with the control. These metabolites corroborate previous findings in clinical and preclinical cohorts. Comprehensive whole-blood metabolomics can provide a robust metabolic marker for more accurate diagnosis and treatment intervention for a disease population.

cFOS expression in the prefrontal cortex correlates with altered cerebral metabolism in developing germ-free mice

Introduction

The microbiota plays a critical role in modulating various aspects of host physiology, particularly through the microbiota-gut-brain (MGB) axis. However, the mechanisms that transduce and affect gut-to-brain communication are still not well understood. Recent studies have demonstrated that dysbiosis of the microbiome is associated with anxiety and depressive symptoms, which are common complications of metabolic syndrome. Germ-free (GF) animal models offer a valuable tool for studying the causal effects of microbiota on the host.

Methods

We employed gene expression and nuclear magnetic resonance (NMR)-based metabolomic techniques to investigate the relationships between brain plasticity and immune gene expression, peripheral immunity, and cerebral and liver metabolism in GF and specific pathogen-free (SPF) mice.

Results

Our principal findings revealed that brain acetate (p = 0.012) was significantly reduced in GF relative to SPF mice, whereas glutamate (p = 0.0013), glutamine (p = 0.0006), and N-acetyl aspartate (p = 0.0046) metabolites were increased. Notably, cFOS mRNA expression, which was significantly decreased in the prefrontal cortex of GF mice relative to SPF mice (p = 0.044), correlated with the abundance of a number of key brain metabolites altered by the GF phenotype, including glutamate and glutamine.

Discussion

These results highlight the connection between the GF phenotype, altered brain metabolism, and immediate-early gene expression. The study provides insight into potential mechanisms by which microbiota can regulate neurotransmission through modulation of the host's brain and liver metabolome, which may have implications for stress-related psychiatric disorders such as anxiety.

Paeoniae Radix Rubra can enhance fatty acid β-oxidation and alleviate gut microbiota disorder in α-naphthyl isothiocyanate induced cholestatic model rats

Cholestasis is the most destructive pathological manifestation of liver disease and available treatments are very limited. Paeoniae Radix Rubra (PRR) is an important traditional Chinese drug used to treat cholestasis. This study combined targeted metabonomics, PCR array analysis, and 16S rRNA sequencing analysis to further clarify the mechanisms of PRR in the treatment of cholestasis. PRR conspicuously reversed the elevation of fatty acids (FFA 14:0 and other 14 fatty acids) and the decrease of organic acids (pyruvic acid and citric acid) in a cholestatic model induced by α-naphthyl isothiocyanate (ANIT). Eight elevated amino acids (L-proline, etc.) and five elevated secondary bile acids (taurohyodeoxycholic acid, etc.) in model rats were also reduced by PRR. Pathway analysis revealed that PRR significantly alleviated eight pathways (β-alanine metabolism). Furthermore, we found that PRR significantly reversed the decrease of Cpt1a, Hadha, Ppara, and Slc25a20 (four genes relevant to fatty acid β-oxidation) mRNAs caused by ANIT, and PRR conspicuously decreased nine acylcarnitines (the forms of fatty acids into mitochondria for β-oxidation) that increased in model rats. These results indicate that PRR could enhance fatty acid β-oxidation, which may be the way for PRR to reduce the levels of 15 fatty acids in the serum of model rats. 16S rRNA sequencing analysis revealed that PRR alleviated gut microbiota disorders in model rats, including upregulating four genera (Coprococcus, Lactobacillus, etc.) and downregulating four genera (Bacteroides, Escherichia, etc.). As the relative abundance of these eight genera was significantly correlated with the levels of the five secondary bile acids (deoxycholic acid, taurolithocholic acid, etc.) reduced by PRR, and Bacteroides and Escherichia were reported to promote the production of secondary bile acid, we inferred that the downregulation of PRR on five secondary bile acids in model rats was inseparable from gut microbiota. Thus, the gut microbiota also might be a potential pharmacological target for the anticholestatic activity of PRR. In conclusion, we consider that the mechanisms of PRR in treating cholestasis include enhancing fatty acid β-oxidation and alleviating gut microbiota disorders.

Comparison of Global Metabolite for Growing Pigs Fed at Metabolizable Energy Requirement for Maintenance

Though the energy requirement for maintenance is an important part of net energy system, little is known of the metabolic characteristics of maintenance energy expenditure. This study was investigated the effect of feeding level at metabolizable energy requirement for maintenance (FLM) on plasma metabolites in growing pigs. Ten barrows (22.5 ± 0.5 kg BW) were kept in metabolism crates and catheterized in the precaval vein during adaptation period. Pigs were fed a corn-soybean meal diet at 782 kJ ME/kg BW^0.6·d⁻¹ during d 1 to 8 and then were refeeding at 2,400 kJ ME/kg BW^0.6·d⁻¹ on d 9. Plasma samples of each pig were collected by catheter on the morning of d 1, 3, 5, 7, 9, and 10, respectively, for metabolomics testing. Results showed that the concentration of plasma urea nitrogen decreased under FLM (p < 0.01) and increased significantly after refeeding (p < 0.01). The concentration of total cholesterol, high-density lipoprotein, low-density lipoprotein, and albumin in plasma were decreased significantly after refeeding (p < 0.01). Eleven identified compounds were up-regulated and six ones were down-regulated under FLM. In conclusion, the energy metabolism of growing pigs was relatively stable after 4 days of feeding at FLM.

Complementary Analytical Platforms of NMR Spectroscopy and LCMS Analysis in the Metabolite Profiling of Isochrysis galbana

This study was designed to profile the metabolites of Isochrysis galbana, an indigenous and less explored microalgae species. ¹H Nuclear Magnetic Resonance (NMR) spectroscopy and Liquid Chromatography-Mass Spectrometry (LCMS) were used to establish the metabolite profiles of five different extracts of this microalga, which are hexane (Hex), ethyl acetate (EtOAc), absolute ethanol (EtOH), EtOH:water 1:1 (AqE), and 100% water (Aq). Partial least square discriminant analysis (PLS–DA) of the generated profiles revealed that EtOAc and Aq extracts contain a diverse range of metabolites as compared to the other extracts with a total of twenty-one metabolites, comprising carotenoids, polyunsaturated fatty acids, and amino acids, that were putatively identified from the NMR spectra. Meanwhile, thirty-two metabolites were successfully annotated from the LCMS/MS data, ten of which (palmitic acid, oleic acid, α-linolenic acid, arachidic acid, cholesterol, DHA, DPA, fucoxanthin, astaxanthin, and pheophytin) were similar to those present in the NMR profile. Another eleven glycerophospholipids were discovered using MS/MS-based molecular network (MN) platform. The results of this study, besides providing a better understanding of I.galbana’s chemical make-up, will be of importance in exploring this species potential as a feed ingredient in the aquaculture industry.

TianJiu therapy for α-naphthyl isothiocyanate-induced intrahepatic cholestasis in rats treated with fresh Ranunculus sceleratus L

ETHNOPHARMACOLOGICAL RELEVANCE

TianJiu (TJ) therapy, one type of cold moxibustion, applies to specific acupuncture points with herbal patches of hot nature, providing a constant irritant to the skin until the presence of hyperemia and blistering. Traditional and clinical reports suggest that TJ is an effective therapy for the treatment of jaundice with fresh Ranunculus sceleratus L. (RS), in which protoanemonin is one of the main irritant constituents. However, the therapeutic effect of TJ treatment with fresh RS against intrahepatic cholestasis has not been studied in animal experiments.

AIM OF THE STUDY

Present study was undertaken to investigate the effect of TJ treatment with fresh RS against intrahepatic cholestasis in rats and provide an experimental basis for the underlying mechanism of TJ therapy.

MATERIALS AND METHODS

Male intrahepatic cholestatic Sprague-Dawley rats induced by 2% α-naphthylisothiocyanate (ANIT, 80 mg/kg B.W.) were treated by TJ therapy with fresh RS. The levels of serum aspartate aminotransferase (AST), alanine aminotransferase (ALT), alkaline phosphatase (ALP), direct bilirubin (DBIL), total bilirubin (TBIL), total bile acid (TBA), hepatic malondialdehyde (MDA) and nitric monoxide (NO), as well as hepatic body ratio, bile flow and hepatic histopathological assay were measured and evaluated to investigate the therapeutic effect of TJ treatment with fresh RS. Phytochemical analysis of fresh and dried RS was performed by gas chromatography-mass spectrometer (GC-MS).

RESULTS

After TJ treatment with fresh RS, the abnormally elevated levels of serum AST, ALT, ALP, DBIL, TBIL and TBA, as well as hepatic MDA and NO at 108 h were reduced significantly (versus model group, P < 0.01). The hepatic body ratio, bile flow and hepatic pathological change of cholestatic rats at 108 h in TJ group were restored when compared with those of model group. Thirty-one compounds including lactones, flavonoids and phenolic acids were identified and determined by GC-MS analysis. The content of protoanemonin in fresh RS (9.49%) was about 25-fold higher than that in dried RS (0.38%).

CONCLUSIONS

TJ treatment with fresh RS exhibited good therapeutic effect on ANIT-induced intrahepatic cholestasis in rats, which may be due to the attenuated oxidative stress in the liver tissue. It is rational for the ancients to choose fresh RS as TJ herbal patches because of its abundant protoanemonin with the character of irritant. The qualitative and quantitative results of GC-MS analysis provided the chemical basis of TJ therapy with fresh RS, which can be regarded as a simple and efficient method for the treatment of cholestasis hepatitis.

Metabonomics analysis of liver in rats administered with chronic low-dose acrylamide

The current study aimed to investigate the hepatotoxicity of rats administered with chronic low-dose acrylamide (AA) by using metabonomics technology on the basis of ultraperformance liquid chromatography-mass spectrometry (UPLC-MS). A total of 40 male Wistar rats were randomly divided into the following four groups: control, low-dose AA (0.2 mg/kg bw, non-carcinogenic end-point based on the induction of morphological nerve changes in rats), middle-dose AA (1 mg/kg bw), and high-dose AA (5 mg/kg bw). The rats continuously received AA by administering it in drinking water daily for 16 weeks. After the treatment, rat livers were collected for metabonomics analysis and histopathology examination. Principal components analysis (PCA) and partial least-squares discriminant analysis (PLS-DA) were used to investigate the metabonomics profile changes in rat liver tissues and screen the potential biomarkers.Fourteen metabolites were identified with significant changes in intensities (increased or decreased compared with the control group) as a result of treatment (p < 0.05 or p < 0.01). These metabolites included tauro-b-muricholic acid, docosapentaenoic acid, sphingosine 1-phosphate, taurodeoxycholic acid, lysoPE(20:5), cervonyl carnitine, linoleyl carnitine, docosahexaenoic acid, lysoPC(20:4), lysoPE(18:3), PA(20:4), stearidonyl carnitine, alpha-linolenic acid, and lysoPA(18:0).Results showed that chronic exposure to AA at NOAEL (0.2 mg/kg bw) exhibited no toxic effect in rat livers at the metabolic level. AA induced oxidative stress to the liver and disrupted lipid metabolism. The results of liver histopathology examination further supported the metabonomic results.

Twenty years of metabonomics: so what has metabonomics done for toxicology?

In 1999 the journal Xenobiotica published a perspective article detailing the new concept of metabonomics and its application to toxicology. The approach was to apply analytical chemistry techniques, and in particular ¹H NMR spectroscopy, to profile biofluids and tissues to assess the metabolic effects of xenobiotics. Metabonomics has been shown to be sensitive not only to organ specific toxicity but also provides information on the cells, tissues and mechanisms involved, as well as their interactions with the host's sex, age, diet and environment. This review assesses the impact of metabonomics on drug toxicology over the past twenty years and its future prospects. These applications include:Pharmacometabonomics - the prediction of drug effects through the analysis of predose, biofluid metabolite profiles, which reflect both genetic and environmental influences on physiology.The microbiomes role in toxicology - understanding how xenobiotics can be modified by the microbiome dramatically changing their impact on the host.Development of expert systems for toxicity prediction.Data fusion of different omics to better understand the underlying mechanisms of drug toxicity.Metabonomics and exposome - understanding how multiple environmental toxicants might interact with the host organism to produce their overall phenotype. While there has been huge growth in the use of metabonomics within toxicology these applications are set to increase as the tools become more sensitive and robust, as well as the increased use of both experimental and in silico databases to aid prediction of toxicology.

Advances of Metabolomics in Fungal Pathogen-Plant Interactions

Plant disease caused by fungus is one of the major threats to global food security, and understanding fungus-plant interactions is important for plant disease control. Research devoted to revealing the mechanisms of fungal pathogen-plant interactions has been conducted using genomics, transcriptomics, proteomics, and metabolomics. Metabolomics research based on mass spectrometric techniques is an important part of systems biology. In the past decade, the emerging field of metabolomics in plant pathogenic fungi has received wide attention. It not only provides a qualitative and quantitative approach for determining the pathogenesis of pathogenic fungi but also helps to elucidate the defense mechanisms of their host plants. This review focuses on the methods and progress of metabolomics research in fungal pathogen-plant interactions. In addition, the prospects and challenges of metabolomics research in plant pathogenic fungi and their hosts are addressed.

Biological System Responses of Dairy Cows to Aflatoxin B1 Exposure Revealed with Metabolomic Changes in Multiple Biofluids

Research on mycotoxins now requires a systematic study of post-exposure organisms. In this study, the effects of aflatoxin B1 (AFB1) on biofluids biomarkers were examined with metabolomics and biochemical tests. The results showed that milk concentration of aflatoxin M1 changed with the addition or removal of AFB1. AFB1 significantly affected serum concentrations of superoxide dismutase (SOD) and malon dialdehyde (MDA), SOD/MDA, and the total antioxidant capacity. Significant differences of volatile fatty acids and NH₃-N were detected in the rumen fluid. Eighteen rumen fluid metabolites, 11 plasma metabolites, and 9 milk metabolites were significantly affected by the AFB1. These metabolites are mainly involved in the pathway of amino acids metabolism. Our results suggest that not only is the study of macro-indicators (milk composition and production) important, but that more attention should be paid to micro-indicators (biomarkers) when assessing the risks posed by mycotoxins to dairy cows.

Melatonin ameliorates ANIT‑induced cholestasis by activating Nrf2 through a PI3K/Akt‑dependent pathway in rats

Cholestasis is a devastating liver condition which is increasing in prevalence worldwide; however, its underlying pathogenic mechanisms remain to be fully elucidated. It was hypothesised that melatonin may alleviate the hepatic injury associated with cholestasis due to its established antioxidant effects. Therefore, the effect and potential anticholestatic properties of melatonin were investigated in rats with α-naphthylisothiocyanate (ANIT)-induced liver injury, a common animal model that mimics the cholestasis-associated liver injury in humans. The rats received intraperitoneal injection of ANIT with or without subsequent treatment with melatonin, and were sacrificed 24 h later. The serum biochemistry parameters of the liver were measured using conventional laboratory assays, and the liver tissue was subjected to conventional histological examination, reverse transcription-quantitative polymerase chain reaction analysis and western blotting. The levels of alanine transaminase, aspartate transaminase, total bilirubin, direct bilirubin, total bile acids, alkaline phosphatase, γ-glutamyl transferase and glutathione were restored in rats treated with melatonin. Histological examination provided further evidence supporting the protective effect of melatonin against ANIT-induced cholestasis. In addition, the mRNA and protein expression levels of glutamate cysteine ligase, phosphorylated Akt and nuclear factor-erythroid 2-related factor-2 were restored in rats treated with melatonin. These findings indicate that melatonin is a natural agent that appears to be promising for the treatment of cholestasis, and that the anticholestatic effects of melatonin involve the alleviation of oxidative stress.

Metabonomics analysis of kidneys in rats administered with chronic low-dose cadmium by ultra-performance liquid chromatography-mass spectrometry

This study aimed to investigate the nephrotoxicity in rats administered with chronic low-dose cadmium (Cd) by ultra-performance liquid chromatography-mass spectrometry. A total of 40 male Sprague-Dawley rats were randomly assigned to four groups, namely: control; low-dose (0.13 mg/kg·body weight [bw]); middle-dose (0.80 mg/kg·bw); and high-dose (4.89 mg/kg·bw). The rats received CdCl₂ daily via drinking water for 24 weeks. Rat kidneys were collected for metabonomics analysis. Principal components analysis and partial least-squares discriminant analysis were used to investigate the metabonomics profile changes in the kidney samples and to screen the potential biomarkers. Ten metabolites were identified in the positive and negative ion modes. Compared with the control group, the intensities of tetranor 12-HETE, uric acid, hypoxanthine, phenylacetylglycine, guanidinosuccinic acid and xanthosine significantly increased (P < 0.01), and those of imidazolelactic acid, lactose 6-phosphate, l-urobilinogen and arachidonic acid significantly decreased (P < 0.01) in the high-dose group. Results showed that exposure to Cd in rats induced oxidative stress to the kidneys and disrupted amino acid metabolism, fatty acid metabolism and energy metabolism.

Metabonomic analysis of toxic action of long-term low-level exposure to acrylamide in rat serum

This study assessed the effects of long-term, low-dose acrylamide (AA) administration in rats using ultra-performance liquid chromatography–mass spectrometry. Forty male Wistar rats were randomly divided into the following four groups: control, low-dose AA (0.2 mg/kg BW), middle-dose AA (1 mg/kg BW), and high-dose AA (5 mg/kg BW). AA was administered to rats via drinking water ad libitum. After 16-week treatment, rat serum was collected for metabonomic analysis. Biochemical tests were further conducted to verify metabolic alterations. Eleven metabolites were identified with significant changes in intensities (increased or reduced) as a result of treatment. These metabolites included citric acid, pantothenic acid, isobutyryl-l-carnitine, eicosapentaenoic acid, docosahexaenoic acid, sphingosine 1-phosphate, LysoPC(20:4), LysoPC(22:6), LysoPE(20:3), undecanedioic acid, and dodecanedioic acid. Results indicate that chronic exposure to AA at no observed adverse effect level does not exert a toxic effect on rats at the body metabolism level. AA disturbed the metabolism of lipids and energy, affected the nervous system of rats, and induced oxidative stress and liver dysfunction.

Metabonomics analysis of quercetin against the nephrotoxicity of acrylamide in rats

This research aimed at studying the effect of quercetin against the nephrotoxicity of acrylamide by metabonomics analysis of kidney tissue.

Metabolomic approaches in the discovery of potential urinary biomarkers of drug-induced liver injury (DILI)

Drug-induced liver injury (DILI) is a major safety issue during drug development, as well as the most common cause for the withdrawal of drugs from the pharmaceutical market. The identification of DILI biomarkers is a labor-intensive area. Conventional biomarkers are not specific and often only appear at significant levels when liver damage is substantial. Therefore, new biomarkers for early identification of hepatotoxicity during the drug discovery process are needed, thus resulting in lower development costs and safer drugs. In this sense, metabolomics has been increasingly playing an important role in the discovery of biomarkers of liver damage, although the characterization of the mechanisms of toxicity induced by xenobiotics remains a huge challenge. These new-generation biomarkers will offer obvious benefits for the pharmaceutical industry, regulatory agencies, as well as a personalized clinical follow-up of patients, upon validation and translation into clinical practice or approval for routine use. This review describes the current status of the metabolomics applied to the early diagnosis and prognosis of DILI and in the discovery of new potential urinary biomarkers of liver injury.

Protective effects of petroleum ether extracts of Herpetospermum caudigerum against α-naphthylisothiocyanate-induced acute cholestasis of rats

ETHNOPHARMACOLOGICAL RELEVANCE

The ripe seeds of Herpetospermum caudigerum have been used in Tibetan folk medicine for treatment of bile or liver diseases including jaundice, hepatitis, intumescences or inflammation. Previously reports suggested that the seed oil and some lignans from H. caudigerum exhibited protective effects against carbon tetrachloride (CCl₄)-induced hepatic damage in rats, which may be related to their free radical scavenging effect. However, the protective effect of H. caudigerum against cholestasis is still not revealed. The aim of the present study was to investigate the pharmacological effect and the chemical constituents of the petroleum ether extract (PEE) derived from H. caudigerum against α-naphthylisothiocyanate (ANIT)-induced acute cholestasis in rats.

MATERIALS AND METHODS

Male cholestatic Sprague-Dawley (SD) rats induced by ANIT (60mg/kg) were orally administered with PEE (350, 700 and 1400mg/kg). Levels of serum alanine aminotransferase (ALT), aspartate aminotransferase (AST), alkaline phosphatase (ALP), γ-Glutamyl transpeptidase (γ-GTP), total bilirubin (TBIL), direct bilirubin (DBIL) and total bile acid (TBA), as well as bile flow, and histopathological assay were evaluated. Hepatic malondialdehyde (MDA), myeloperoxidase (MPO), superoxide dismutase (SOD), glutathione S-transferase (GST), and nitric monoxide (NO) in liver were measured to explore the possible protective mechanisms. Phytochemical analysis of PEE was performed by gas chromatography-mass spectrometer (GC-MS).

RESULTS

PEE have exhibited significant and dose-dependent protective effect on ANIT-induced liver injury by reduce the increases in serum levels of ALT, AST, ALP, γ-GTP, TBIL, DBIL and TBA, restore the bile flow in cholestatic rats, and reduce the severity of the pathological tissue damage induced by ANIT. Hepatic MDA, MPO and NO contents in liver tissue were reduced, while SOD and GST activities were elevated in liver tissue. 49 compounds were detected and 39 of them were identified by GC-MS analysis, in which long-chain fatty acids were the main constituents.

CONCLUSIONS

PEE exhibited a dose-dependently protective effect on ANIT-induced liver injury in cholestatic rats with the potential mechanism of attenuated oxidative stress in the liver tissue, and the possible active compounds were long-chain fatty acids.

Serum Metabolomics of Burkitt Lymphoma Mouse Models

Burkitt lymphoma (BL) is a rare and highly aggressive type of non-Hodgkin lymphoma. The mortality rate of BL patients is very high due to the rapid growth rate and frequent systemic spread of the disease. A better understanding of the pathogenesis, more sensitive diagnostic tools and effective treatment methods for BL are essential. Metabolomics, an important aspect of systems biology, allows the comprehensive analysis of global, dynamic and endogenous biological metabolites based on their nuclear magnetic resonance (NMR) and mass spectrometry (MS). It has already been used to investigate the pathogenesis and discover new biomarkers for disease diagnosis and prognosis. In this study, we analyzed differences of serum metabolites in BL mice and normal mice by NMR-based metabolomics. We found that metabolites associated with energy metabolism, amino acid metabolism, fatty acid metabolism and choline phospholipid metabolism were altered in BL mice. The diagnostic potential of the metabolite differences was investigated in this study. Glutamate, glycerol and choline had a high diagnostic accuracy; in contrast, isoleucine, leucine, pyruvate, lysine, α-ketoglutarate, betaine, glycine, creatine, serine, lactate, tyrosine, phenylalanine, histidine and formate enabled the accurate differentiation of BL mice from normal mice. The discovery of abnormal metabolism and relevant differential metabolites may provide useful clues for developing novel, noninvasive approaches for the diagnosis and prognosis of BL based on these potential biomarkers.

NMR-based metabonomics study on the effect of Gancao in the attenuation of toxicity in rats induced by Fuzi

ETHNOPHARMACOLOGICAL RELEVANCE

Fuzi, the processed lateral root of Aconitum carmichaelii Debeaux, is a traditional Chinese medicine used for its analgesic, antipyretic, anti-rheumatoid arthritis and anti-inflammation effects; however, it is also well known for its toxicity. Gancao, the root of Glycyrrhiza uralensis Fisch., is often used concurrently with Fuzi to alleviate its toxicity. However, the mechanism of detoxication is still not well clear.

AIM OF THE STUDY

In this study, the effect of Gancao on the metabolic changes induced by Fuzi was investigated by NMR-based metabonomic approaches.

MATERIALS AND METHODS

Fifty male Wistar rats were randomly divided into five groups (group A: control, group B: Fuzi decoction alone, group C: Gancao decoction alone, group D: Fuzi decoction and Gancao decoction simultaneously, group E: Fuzi decoction 5h after Gancao decoction) and urine samples were collected for NMR-based metabolic profiling analysis. Statistical analyses such as unsupervised PCA, t-test, hierarchical cluster, and pathway analysis were used to detect the effects of Gancao on the metabolic changes induced by Fuzi.

RESULTS

The behavioral and biochemical characteristics showed that Fuzi exhibited toxic effects on treated rats (group B) and statistical analyses showed that their metabolic profiles were in contrast to those in groups A and C. However, when Fuzi was administered with Gancao, the metabolic profiles became similar to controls, whereby Gancao reduced the levels of trimethylamine N-oxide, betaine, dimethylglycine, valine, acetoacetate, citrate, fumarate, 2-ketoglutarate and hippurate, and regulated the concentrations of taurine and 3-hydroxybutyrate, resulting in a decrease in toxicity. Furthermore, important pathways that are known to be involved in the effect of Gancao on Fuzi, including phenylalanine, tyrosine and tryptophan biosynthesis, the synthesis and degradation of ketone bodies, and the TCA cycle, were altered in co-treated rats.

CONCLUSIONS

Gancao treatment mitigated the metabolic changes altered by Fuzi administration in rats, demonstrating that dosing with Gancao could reduce the toxicity of Fuzi at the metabolic level. Fuzi and Gancao administered simultaneously resulted in improved toxicity reduction than when Gancao was administrated 5h prior to Fuzi. In summary, co-administration of Gancao with Fuzi reduces toxicity at the metabolic level.

1H NMR-Linked Metabolomics Analysis of Liver from a Mouse Model of NP-C1 Disease

Clinical manifestations of Niemann-Pick type C1 (NP-C1) disease include neonatal hepatosplenomegaly and in some patients progressive liver dysfunction and failure. This study involved a ¹H NMR-linked metabolomics analysis of liver samples collected from a NP-C1 disease mutant mouse model in order to explore time-dependent imbalances in metabolic pathways associated with NP-C1 liver dysfunction, including fibrosis. NP-C1 mutant (Npc1^-/-; NP-C1), control (Npc1^+/+; WT), and NP-C1 heterozygous mice (Npc1^+/-; HET) were generated from heterozygote matings. Aqueous extracts of these liver samples collected at time points of 3, 6, 9, and 11 weeks were subjected to high-resolution NMR analysis, and multivariate (MV) metabolomics analyses of data sets acquired were performed. A MV random forests (RFs) model effectively discriminated between NP-C1 and a combined WT/HET hepatic NMR profiles with very high predictive accuracy and reliability. Key distinguishing features included significant upregulations in the hepatic concentrations of phenylalanine, tyrosine, glutamate, lysine/ornithine, valine, threonine, and hypotaurine/methionine, and diminished levels of nicotinate/niacinamide, inosine, phosphoenolpyruvate, and 3-hydroxyphenylacetate. Quantitative pathway topological analysis confirmed that imbalances in tyrosine biosynthesis, and hepatic phenylalanine, tyrosine, glutamate/glutamine, and nicotinate/niacinamide metabolism were involved in the pathogenesis of NP-C1 disease-associated liver dysfunction/damage. ¹H NMR-linked metabolomics analysis provides valuable biomarker information regarding hepatic dysfunction or damage in NP-C1 disease.

Revealing Potential Biomarkers of Functional Dyspepsia by Combining 1H NMR Metabonomics Techniques and an Integrative Multi-objective Optimization Method

Metabonomics methods have gradually become important auxiliary tools for screening disease biomarkers. However, recognition of metabolites or potential biomarkers closely related to either particular clinical symptoms or prognosis has been difficult. The current study aims to identify potential biomarkers of functional dyspepsia (FD) by a new strategy that combined hydrogen nuclear magnetic resonance (¹H NMR)-based metabonomics techniques and an integrative multi-objective optimization (LPIMO) method. First, clinical symptoms of FD were evaluated using the Nepean Dyspepsia Index (NDI), and plasma metabolic profiles were measured by ¹H NMR. Correlations between the key metabolites and the NDI scores were calculated. Then, LPIMO was developed to identify a multi-biomarker panel by maximizing diagnostic ability and correlation with the NDI score. Finally, a KEGG database search elicited the metabolic pathways in which the potential biomarkers are involved. The results showed that glutamine, alanine, proline, HDL, β-glucose, α-glucose and LDL/VLDL levels were significantly altered in FD patients. Among them, phosphatidycholine (PtdCho) and leucine/isoleucine (Leu/Ile) were positively and negatively correlated with the NDI Symptom Index (NDSI) respectively. Our procedure not only significantly improved the credibility of the biomarkers, but also demonstrated the potential of further explorations and applications to diagnosis and treatment of complex disease.

The Progress of Metabolomics Study in Traditional Chinese Medicine Research

Traditional Chinese medicine (TCM) has played important roles in health protection and disease treatment for thousands of years in China and has gained the gradual acceptance of the international community. However, many intricate issues, which cannot be explained by traditional methods, still remain, thus, new ideas and technologies are needed. As an emerging system biology technology, the holistic view adopted by metabolomics is similar to that of TCM, which allows us to investigate TCM with complicated conditions and multiple factors in depth. In this paper, we tried to give a timely and comprehensive update about the methodology progression of metabolomics, as well as its applications, in different fields of TCM studies including quality control, processing, safety and efficacy evaluation. The herbs investigated by metabolomics were selected for detailed examination, including Anemarrhena asphodeloides Bunge, Atractylodes macrocephala Kidd, Pinellia ternate, etc.; furthermore, some valuable results have been obtained and summarized. In conclusion, although the study of metabolomics is at the early phase and requires further scrutiny and validation, it still provides bright prospects to dissect the synergistic action of multiple components from TCM. Overall, with the further development of analytical techniques, especially multi-analysis techniques, we expect that metabolomics will greatly promote TCM research and the establishment of international standards, which is beneficial to TCM modernization.

Metabolomics Reveals that Aryl Hydrocarbon Receptor Activation by Environmental Chemicals Induces Systemic Metabolic Dysfunction in Mice

Environmental exposure to dioxins and dioxin-like compounds poses a significant health risk for human health. Developing a better understanding of the mechanisms of toxicity through activation of the aryl hydrocarbon receptor (AHR) is likely to improve the reliability of risk assessment. In this study, the AHR-dependent metabolic response of mice exposed to 2,3,7,8-tetrachlorodibenzofuran (TCDF) was assessed using global (1)H nuclear magnetic resonance (NMR)-based metabolomics and targeted metabolite profiling of extracts obtained from serum and liver. (1)H NMR analyses revealed that TCDF exposure suppressed gluconeogenesis and glycogenolysis, stimulated lipogenesis, and triggered inflammatory gene expression in an Ahr-dependent manner. Targeted analyses using gas chromatography coupled with mass spectrometry showed TCDF treatment altered the ratio of unsaturated/saturated fatty acids. Consistent with this observation, an increase in hepatic expression of stearoyl coenzyme A desaturase 1 was observed. In addition, TCDF exposure resulted in inhibition of de novo fatty acid biosynthesis manifested by down-regulation of acetyl-CoA, malonyl-CoA, and palmitoyl-CoA metabolites and related mRNA levels. In contrast, no significant changes in the levels of glucose and lipid were observed in serum and liver obtained from Ahr-null mice following TCDF treatment, thus strongly supporting the important role of the AHR in mediating the metabolic effects seen following TCDF exposure.

1H NMR-based metabolomics investigation of copper-laden rat: a model of Wilson's disease

BACKGROUND AND PURPOSE

Wilson's disease (WD), also known as hepatoleticular degeneration (HLD), is a rare autosomal recessive genetic disorder of copper metabolism, which causes copper to accumulate in body tissues. In this study, rats fed with copper-laden diet are used to render the clinical manifestations of WD, and their copper toxicity-induced organ lesions are studied. To investigate metabolic behaviors of 'decoppering' process, penicillamine (PA) was used for treating copper-laden rats as this chelating agent could eliminate excess copper through the urine. To date, there has been limited metabolomics study on WD, while metabolic impacts of copper accumulation and PA administration have yet to be established.

MATERIALS AND METHODS

A combination of 1HNMR spectroscopy and multivariate statistical analysis was applied to examine the metabolic profiles of the urine and blood serum samples collected from the copper-laden rat model of WD with PA treatment.

RESULTS

Copper accumulation in the copper-laden rats is associated with increased lactate, creatinine, valine and leucine, as well as decreased levels of glucose and taurine in the blood serum. There were also significant changes in p-hydroxyphenylacetate (p-HPA), creatinine, alpha-ketoglutarate (α-KG), dimethylamine, N-acetylglutamate (NAG), N-acetylglycoprotein (NAC) in the urine of these rats. Notably, the changes in p-HPA, glucose, lactate, taurine, valine, leucine, and NAG were found reversed following PA treatment. Nevertheless, there were no changes for dimethylamine, α-KG, and NAC as a result of the treatment. Compared with the controls, the concentrations of hippurate, formate, alanine, and lactate were changed when PA was applied and this is probably due to its side effect. A tool named SMPDB (Small Molecule Pathway Database) is introduced to identify the metabolic pathway influenced by the copper-laden diet.

CONCLUSION

The study has shown the potential application of NMR-based metabolomic analysis in providing further insights into the molecular mechanism underlying disorder due to WD.

Effects of chlorpyrifos on the metabolome of the freshwater carp, Cyprinus carpio

This study investigated the effects of waterborne chlorpyrifos with concentrations of 1 and 100 µg/L for L and H-groups, respectively, on metabolome profiles of carp plasma using (1)H-NMR. Principal component analysis suggests that chlorpyrifos exposure firstly affected in L and H-groups on day 2 or 4, and followed a second effect in both exposure groups on day 14. Levels of metabolites related to the energy production in the body, such as glucose, glycerol, valine, leucine, isoleucine, lactate, alanine, 3-D-hydroxybutyrates and acetoacetate, significantly changed by exposures of chlorpyrifos. Those results suggest that energy production was severely affected in carp. The exposure could also be highly elevated ammonia levels especially in H-group due to severe convulsion in muscle caused by the inhibition of acetylcholinesterase activity.

Metabolomic analysis of arginine metabolism in acute hepatic injury in rats

To clarify the relationship between arginine metabolism and hepatic injury, metabolomic analysis was performed in rats treated with 3 representative hepatotoxicants, monocrotaline (MCT), concanavalin A (ConA), and α-naphthyl isothiocyanate (ANIT); or a myotoxicant, tetramethyl-p-phenylenediamine (TMPD). A single dose of MCT, ConA, or ANIT dose-dependently induced hepatocellular necrosis accompanied by decreased blood arginine and increased blood alanine aminotransferase (ALT) and arginase. A close correlation was detected between arginine and ALT (r = -0.746, -0.795, -0.787 for MCT, ConA, ANIT, respectively) or between arginine and arginase (r = -0.605, -0.808, -0.672 for MCT, ConA, ANIT, respectively) in all three hepatic injury models. In contrast, neither hepatocellular necrosis nor alterations in arginine were found in the skeletal muscle injury model, although ALT was slightly increased. An in vitro assay revealed that blood samples obtained from ConA-treated rats transformed external arginine to ornithine, and the reaction was totally inhibited by an arginase inhibitor. These results suggest that blood arginase plays a crucial role in arginine metabolism associated with hepatic injury. In metabolomic analysis, nearly 450 endogenous metabolites were identified in blood obtained from all the models. Among the 13 metabolites involved in arginine metabolism, decreased arginine and increased ornithine occurred in common in the hepatic injury models, whereas citrulline and other metabolites were not altered. These results indicate that arginine metabolism, especially the arginine-to-ornithine pathway, is altered in association with acute hepatic injury. Furthermore, blood arginine and ornithine are possibly specific biomarkers for hepatic injury.

Metabonomics study of the effects of pretreatment with glycyrrhetinic acid on mesaconitine-induced toxicity in rats

ETHNOPHARMACOLOGICAL RELEVANCE

Aconitum carmichaelii Debx. (Fuzi), a commonly use traditional Chinese medicine (TCM), has often been used in combination with Rhizoma Glycyrrhizae (Gancao) to reduce its toxicity due to diester diterpenoid alkaloids aconitine, mesaconitine, and hypaconitine. However, the mechanism of detoxication is still unclear. Glycyrrhetinic acid (GA) is the metabolite of glycyrrhizinic acid (GL), the major component of Gancao. In present study, the effect of GA on the changes of metabolic profiles induced by mesaconitine was investigated using NMR-based metabolomic approaches.

MATERIALS AND METHODS

Fifteen male Wistar rats were divided into a control group, a group administered mesaconitine alone, and a group administered mesaconitine with one pretreatment with GA. Their urine samples were used for NMR spectroscopic metabolic profiling. Statistical analyses such as orthogonal projections to latent structures-discriminant analysis (OPLS-DA), t-test, hierarchical cluster, and pathway analysis were used to detect the effects of pretreatment with GA on mesaconitine-induced toxicity.

RESULTS

The OPLS-DA score plots showed the metabolic profiles of GA-pretreated rats apparently approach to those of normal rats compared to mesaconitine-induced rats. From the t-test and boxplot results, the concentrations of leucine/isoleucine, lactate, acetate, succinate, trimethylamine (TMA), dimethylglycine (DMG), 2-oxo-glutarate, creatinine/creatine, glycine, hippurate, tyrosine and benzoate were significantly changed in metabolic profiles of mesaconitine-induced rats. The disturbed metabolic pathways include amino acid biosynthesis and metabolism.

CONCLUSIONS

GA-pretreatment can mitigate the metabolic changes caused by mesaconitine-treatment on rats, indicating that prophylaxis with GA could reduce the toxicity of mesaconitine at the metabolic level.

Slow-MAS NMR: A new technology for in vivo metabolomic studies

Obtaining detailed in vivo metabolic information has been identified as key elements of better understanding the efficacy and toxicity of new therapies. A new nuclear magnetic resonance (NMR) technology called LOCMAT is reported in this paper that yields substantially increased spectral resolution in spatially localized in vivo H NMR metabolite spectra, as illustrated by measurements in the liver of a live mouse. LOCMAT promises to significantly enhance the utility of NMR spectroscopy for biomedical research.:

1H NMR based metabolic profiling in Crohn's disease by random forest methodology

The present study was designed to search for metabolic biomarkers and their correlation with serum zinc in Crohn's disease patients. Crohn's disease (CD) is a form of inflammatory bowel disease that may affect any part of the gastrointestinal tract and can be difficult to diagnose using the clinical tests. Thus, introduction of a novel diagnostic method would be a major step towards CD treatment. Proton nuclear magnetic resonance spectroscopy ((1)H NMR) was employed for metabolic profiling to find out which metabolites in the serum have meaningful significance in the diagnosis of CD. CD and healthy subjects were correctly classified using random forest methodology. The classification model for the external test set showed a 94% correct classification of CD and healthy subjects. The present study suggests Valine and Isoleucine as differentiating metabolites for CD diagnosis. These metabolites can be used for screening of risky samples at the early stages of CD diagnoses. Moreover, a robust random forest regression model with good prediction outcomes was developed for correlating serum zinc level and metabolite concentrations. The regression model showed the correlation (R(2)) and root mean square error values of 0.83 and 6.44, respectively. This model suggests valuable clues for understanding the mechanism of zinc deficiency in CD patients.

Characterization of rational biomarkers accompanying fever in yeast-induced pyrexia rats using urine metabolic footprint analysis

Fever is a prominent feature of diseases and is an ongoing process that is always accompanied by metabolic changes in the body system. Despite the success of temperature regulation theory, the underlying biological process remains unclear. To truly understand the nature of the febrile response, it is crucial to confirm the biomarkers during the entire biological process. In the current study, a 73-h metabolic footprint analysis of the urine from yeast-induced pyrexia rats was performed using ultra-performance liquid chromatography coupled with quadrupole time-of-flight mass spectrometry. Potential biomarkers were selected using orthogonal partial least squares-discriminate analysis (OPLS-DA), the rational biomarkers were verified by Pearson correlation analysis, and the predictive power was evaluated using receiver operator characteristic (ROC) curves. A metabolic network constructed using traditional Chinese medicine (TCM) grammar systems was used to validate the rationality of the verified biomarkers. Finally, five biomarkers, including indoleacrylic acid, 3-methyluridine, tryptophan, nicotinuric acid and PI (37:3), were confirmed as rational biomarkers because their correlation coefficients were all greater than 0.87 and because all of the correlation coefficients between any pair of these biomarkers were higher than 0.75. The areas under the ROC curves were all greater than 0.84, and their combined predictive power was considered reliable because the greatest area under the ROC curve was 0.968. A metabolic network also demonstrated the rationality of these five biomarkers. Therefore, these five metabolites can be adopted as rational biomarkers to reflect the process of the febrile response in inflammation-induced pyrexia.

Pattern recognition analysis for hepatotoxicity induced by acetaminophen using plasma and urinary 1H NMR-based metabolomics in humans

Drug-induced liver injury (DILI) is currently an increasingly relevant health issue. However, available biomarkers do not reliably detect or quantify DILI risk. Therefore, the purpose of this study was to comparatively evaluate plasma and urinary biomarkers obtained from humans treated with acetaminophen (APAP) using a metabolomics approach and a proton nuclear magnetic resonance (NMR) platform. APAP (3 g/day, two 500 mg tablets every 8 h) was administered to 20 healthy Korean males (age, 20-29 years) for 7 days. Urine was collected daily before and during dosing and 6 days after the final dose. NMR spectra of these urine samples were analyzed using principal component analysis (PCA) and partial least-squares-discrimination analysis. Although the activities of aspartate aminotransferase and lactate dehydrogenase were significantly increased 7 days post-APAP treatment, serum biochemical parameters of aspartate aminotransferase, alanine aminotransferase, alkaline phosphatase, total bilirubin, γ-glutamyl transpeptidase, and lactate dehydrogenase were within normal range of hepatic function. However, urine and plasma (1)H NMR spectroscopy revealed different clustering between predosing and after APAP treatment for global metabolomic profiling through PCA. Urinary endogenous metabolites of trimethylamine-N-oxide, citrate, 3-chlorotyrosine, phenylalanine, glycine, hippurate, and glutarate as well as plasma endogenous metabolites such as lactate, glucose, 3-hydroxyisovalerate, isoleucine, acetylglycine, acetone, acetate, glutamine, ethanol, and isobutyrate responded significantly to APAP dosing in humans. Urinary and plasma endogenous metabolites were more sensitive than serum biochemical parameters. These results might be applied to predict or screen potential hepatotoxicity caused by other drugs using urinary and plasma (1)H NMR analyses.

Enhanced green fluorescent protein transgenic expression in vivo is not biologically inert

Enhanced green fluorescent protein (EGFP) is a widely used biological reporter. However, the effects of EGFP expression in vivo are still unclear. To investigate the effects of EGFP transgenic expression in vivo, we employed an NMR-based metabonomics method to analyze the metabonome of EGFP transgenic mice. The results show that the metabonomes of urine, liver, and kidney of the EGFP transgenic mice are different from their wild-type counterparts. The EGFP mice expressed high levels of urinary 3-ureidopropionate, which is due to the down-regulated transcriptional level of β-ureidopropionase. The expression of EGFP in vivo also affects other metabolic pathways, including nucleic acid metabolism, energy utilization, and amino acids catabolism. These findings indicate that EGFP transgenic expression is not as inert as has been considered. Our investigation provides a holistic view on the effect of EGFP expression in vivo, which is useful when EGFP is employed as a functional biological indicator. Our work also highlights the potential of a metabonomics strategy in studying the association between molecular phenotypes and gene function.

Estimation of psychological stress in humans: a combination of theory and practice

Stress has long been known to increase susceptibility to health disorders. In 2009, American Psychological Association further established association of stress to serious health problems. However, a quantitative and accurate way to evaluate and estimate stress status of individuals is still a big challenge. It has been shown, in large animal models using cattle, that psychological stress can be quantified as well as disease susceptibility could be predicted through biomarker discovery. Taking cue from those studies, we have evaluated and estimated psychological stress level of individuals theoretically and validated experimentally. Various biomarkers have also been identified which can be associated to psychological stress to predict stress status of unknown individuals.

Pharmacometabolomic approach to predict QT prolongation in guinea pigs

Drug-induced torsades de pointes (TdP), a life-threatening arrhythmia associated with prolongation of the QT interval, has been a significant reason for withdrawal of several medicines from the market. Prolongation of the QT interval is considered as the best biomarker for predicting the torsadogenic risk of a new chemical entity. Because of the difficulty assessing the risk for TdP during drug development, we evaluated the metabolic phenotype for predicting QT prolongation induced by sparfloxacin, and elucidated the metabolic pathway related to the QT prolongation. We performed electrocardiography analysis and liquid chromatography-mass spectroscopy-based metabolic profiling of plasma samples obtained from 15 guinea pigs after administration of sparfloxacin at doses of 33.3, 100, and 300 mg/kg. Principal component analysis and partial least squares modelling were conducted to select the metabolites that substantially contributed to the prediction of QT prolongation. QTc increased significantly with increasing dose (r = 0.93). From the PLS analysis, the key metabolites that showed the highest variable importance in the projection values (>1.5) were selected, identified, and used to determine the metabolic network. In particular, cytidine-5'-diphosphate (CDP), deoxycorticosterone, L-aspartic acid and stearic acid were found to be final metabolomic phenotypes for the prediction of QT prolongation. Metabolomic phenotypes for predicting drug-induced QT prolongation of sparfloxacin were developed and can be applied to cardiac toxicity screening of other drugs. In addition, this integrative pharmacometabolomic approach would serve as a good tool for predicting pharmacodynamic or toxicological effects caused by changes in dose.

A metabonomics investigation of multiple sclerosis by nuclear magnetic resonance

Multiple sclerosis (MS) is a nervous system disease that affects the fatty myelin sheaths around the axons of the brain and spinal cord, leading to demyelination and a broad range of signs and symptoms. MS can be difficult to diagnose because its signs and symptoms may be similar to other medical problems. To find out which metabolites in serum are effective for the diagnosis of MS, we utilized metabolic profiling using proton nuclear magnetic resonance spectroscopy ((1)H-NMR). Random forest (RF) was used to classify the MS patients and healthy subjects. Atomic absorption spectroscopy was used to measure the serum levels of selenium. The results showed that the levels of selenium were lower in the MS group, when compared with the control group. RF was used to identify the metabolites that caused selenium changes in people with MS by building a correlation model between these metabolites and serum levels of selenium. For the external test set, the obtained classification model showed a 93% correct classification of MS and healthy subjects. The regression model of levels of selenium and metabolites showed the correlation (R(2)) value of 0.88 for the external test set. The results indicate the suitability of NMR as a screen for identifying MS patients and healthy subjects. A novel model with good prediction outcomes was constructed between serum levels of selenium and NMR data.

Metabolic influence of acute cyadox exposure on Kunming mice

Cyadox is an antibiotic drug and has the potential to be used as a feedstuff additive in promoting the growth of animals. However, the toxicity of cyadox should be fully assessed before application, and this has prompted the current investigation on the metabolic responses of mice to cyadox exposure, using a metabonomic technique. Three groups of Kunming mice were respectively given a single dose of cyadox at three different concentrations (100, 650, and 4000 mg/kg body weight) via gavage. We present here the metabolic alterations of urine, plasma, liver, and renal medulla extracts induced by cyadox exposure. The metabolic alterations induced by cyadox exposure are dose-dependent, and metabolic recovery is achieved only for low and moderate levels of cyadox exposure during the experimental period. Cyadox exposure resulted in a disturbance of gut microbiota, which is manifested in depleted levels of urinary hippurate, trimethylamine-N-oxide (TMAO), dimethylamine (DMA), and trimethylamine (TMA). In addition, mice exposed to cyadox at high levels caused accumulations of amino acids and depletions of nucleotides in the liver. Furthermore, marked elevations of nucleotides and a range of organic osmolytes, such as myo-inositol, choline, and glycerophosphocholine (GPC), and decreased levels of amino acids are observed in the renal medulla of cyadox-exposed mice. These results suggest that cyadox exposure causes inhibition of amino acid metabolism in the liver and disturbance of gut microbiota community, influencing osmolytic homeostasis and nucleic acids synthesis in both the liver and the kidney. Our work provides a comprehensive view of the toxicological effects of cyadox, which is important in animal and human food safety.

Metabolomics in lung inflammation:a high-resolution (1)h NMR study of mice exposedto silica dust

ABSTRACT Here we report the first (1)H NMR metabolomics studies on excised lungs and bronchoalveolar lavage fluid (BALF) from mice exposed to crystalline silica. High-resolution (1)H NMR metabolic profiling on intact excised lungs was performed using slow magic angle sample spinning (slow-MAS) (1)H PASS (phase-altered spinning sidebands) at a sample spinning rate of 80 Hz. Metabolic profiling on BALF was completed using fast magic angle spinning at 2 kHz. Major findings are that the relative concentrations of choline, phosphocholine (PC), and glycerophosphocholine (GPC) were statistically significantly increased in silica-exposed mice compared to sham controls, indicating an altered membrane choline phospholipids metabolism (MCPM). The relative concentrations of glycogen/glucose, lactate, and creatine were also statistically significantly increased in mice exposed to silica dust, suggesting that cellular energy pathways were affected by silica dust. Elevated levels of glycine, lysine, glutamate, proline, and 4-hydroxyproline were also increased in exposed mice, suggesting the activation of a collagen pathway. Furthermore, metabolic profiles in mice exposed to silica dust were found to be spatially heterogeneous, consistent with regional inflammation revealed by in vivo magnetic resonance imaging (MRI).

The role of metabolic biomarkers in drug toxicity studies

ABSTRACT Metabolic profiling is a technique that can potentially provide more sensitive and specific biomarkers of toxicity than the current clinical measures benefiting preclinical and clinical drug studies. Both nuclear magnetic resonance (NMR) and mass spectrometry (MS) platforms have been used for metabolic profiling studies of drug toxicity. Not only can both techniques provide novel biomarker(s) of toxicity but the combination of both techniques gives a broader range of metabolites evaluated. Changes in metabolic patterns can provide insight into mechanism(s) of toxicity and help to eliminate a potentially toxic new chemical entity earlier in the developmental process. Metabolic profiling offers numerous advantages in toxicological research and screening as sample collection and preparation are relatively simple. Further, sample throughput, reproducibility, and accuracy are high. The area of drug toxicity of therapeutic compounds has already been impacted by metabolic profiling studies and will continue to be impacted as new, more specific biomarker(s) are found. In order for a biomarker or pattern of biomarkers to be accepted, it must be shown that they originate from the target tissue of interest. Metabolic profiling studies are amenable to any biofluid or tissue sample making it possible to link the changes noted in urine for instance as originating from renal injury. Additionally, the ease of sample collection makes it possible to follow a single animal or subject over time in order to determine whether and when the toxicity resolves itself. This review focuses on the advantages of metabolic profiling for drug toxicity studies.

Revealing metabolite biomarkers for acupuncture treatment by linear programming based feature selection

Background

Acupuncture has been practiced in China for thousands of years as part of the Traditional Chinese Medicine (TCM) and has gradually accepted in western countries as an alternative or complementary treatment. However, the underlying mechanism of acupuncture, especially whether there exists any difference between varies acupoints, remains largely unknown, which hinders its widespread use.

Results

In this study, we develop a novel Linear Programming based Feature Selection method (LPFS) to understand the mechanism of acupuncture effect, at molecular level, by revealing the metabolite biomarkers for acupuncture treatment. Specifically, we generate and investigate the high-throughput metabolic profiles of acupuncture treatment at several acupoints in human. To select the subsets of metabolites that best characterize the acupuncture effect for each meridian point, an optimization model is proposed to identify biomarkers from high-dimensional metabolic data from case and control samples. Importantly, we use nearest centroid as the prototype to simultaneously minimize the number of selected features and the leave-one-out cross validation error of classifier. We compared the performance of LPFS to several state-of-the-art methods, such as SVM recursive feature elimination (SVM-RFE) and sparse multinomial logistic regression approach (SMLR). We find that our LPFS method tends to reveal a small set of metabolites with small standard deviation and large shifts, which exactly serves our requirement for good biomarker. Biologically, several metabolite biomarkers for acupuncture treatment are revealed and serve as the candidates for further mechanism investigation. Also biomakers derived from five meridian points, Zusanli (ST36), Liangmen (ST21), Juliao (ST3), Yanglingquan (GB34), and Weizhong (BL40), are compared for their similarity and difference, which provide evidence for the specificity of acupoints.

Conclusions

Our result demonstrates that metabolic profiling might be a promising method to investigate the molecular mechanism of acupuncture. Comparing with other existing methods, LPFS shows better performance to select a small set of key molecules. In addition, LPFS is a general methodology and can be applied to other high-dimensional data analysis, for example cancer genomics.

¹H NMR-based metabolomics approach to assess toxicity of bunker a heavy oil to freshwater carp, Cyprinus carpio

Using a ¹H NMR metabolomics approach, the effects of dietary exposure of bunker A heavy oil (0.01, 0.1, 1, and 5% in diet) on freshwater carp, Cyprinus carpio, were examined. Statistical analysis by PCA score plots showed that the amount of metabolites in exposure groups 0.1, 1, and 5% differed from those in the control group. Although no discernible effects on metabolites were noted in the 0.1% exposure group as well as in the lowest concentration (0.01%) group, several metabolites such as amino acid (e.g., leucine, isoleucine, valine, glutamine, histidine, proline, and methionine), 3-D-hydroxybutyrate, and glycerol were elevated, while another metabolite such as formate was reduced in 1 and 5% groups. These changes in the metabolites associated with the tri-carboxylic-acid (TCA) cycle suggest that oil exposure resulted in the disturbance of the TCA cycle in the liver of the carp. Isobutyrate, a marker of anoxia, was also increased in 1 and 5% exposures groups and was directly related to low hemoglobin concentrations leading to reduced oxygen transport by blood. In addition, significant elevation of creatinine in the plasma of carps exposed to 5% heavy oil suggests disturbance in kidney function. Thus, metabolomics approach can detect toxic effects of hazardous pollutants on fish.

Pharmacometabonomic investigation of dynamic metabolic phenotypes associated with variability in response to galactosamine hepatotoxicity

Galactosamine (galN) is widely used as an in vivo model of acute liver injury. We have applied an integrative approach, combining histopathology, clinical chemistry, cytokine analysis, and nuclear magnetic resonance (NMR) spectroscopic metabolic profiling of biofluids and tissues, to study variability in response to galactosamine following successive dosing. On re-challenge with galN, primary non-responders displayed galN-induced hepatotoxicity (induced response), whereas primary responders exhibited a less marked response (adaptive response). A systems-level metabonomic approach enabled simultaneous characterization of the xenobiotic and endogenous metabolic perturbations associated with the different response phenotypes. Elevated serum cytokines were identified and correlated with hepatic metabolic profiles to further investigate the inflammatory response to galN. The presence of urinary N-acetylglucosamine (glcNAc) correlated with toxicological outcome and reflected the dynamic shift from a resistant to a sensitive phenotype (induced response). In addition, the urinary level of glcNAc and hepatic level of UDP-N-acetylhexosamines reflected an adaptive response to galN. The unique observation of galN-pyrazines and altered gut microbial metabolites in fecal profiles of non-responders suggested that gut microfloral metabolism was associated with toxic outcome. Pharmacometabonomic modeling of predose urinary and fecal NMR spectroscopic profiles revealed a diverse panel of metabolites that classified the dynamic shift between a resistant and sensitive phenotype. This integrative pharmacometabonomic approach has been demonstrated for a model toxin; however, it is equally applicable to xenobiotic interventions that are associated with wide variation in efficacy or toxicity and, in particular, for prediction of susceptibility to toxicity.

Metabolic profiling of the rat liver after chronic ingestion of alpha-naphthylisothiocyanate using in vivo and ex vivo magnetic resonance spectroscopy

Certain human diseases affecting the biliary tree can be modeled in rats by ingestion of the hepatobiliary toxin alpha-naphthylisothiocyanate (ANIT). Phosphorus magnetic resonance spectroscopy (MRS) allows the noninvasive monitoring of cell dynamics through detection of phosphodiesters (PDE) and phosphomonoesters (PME). Hepatic (31)P MRS techniques were therefore used to study the toxic effects of low-dose chronic ANIT ingestion, with a view toward providing biomarkers sensitive to hepatobiliary dysfunction and cholestatic liver injury. Rats were fed an ANIT supplemented diet at three doses (ANIT_0.05%, ANIT_0.04%, and ANIT_0.025%) for 2 weeks. Data from in vivo MRS were compared with results from pair-fed controls (PFCs). Blood and tissue samples were collected at 2 weeks for clinical chemistry, histology, and (1)H magic angle spinning MRS. Increases in PDE, relative to total phosphorus (tPh), were detected in both the ANIT_0.05% and ANIT_0.04% groups (0.07 ± 0.01 and 0.08 ± 0.01, respectively) relative to PFC groups (0.03 ± 0.01 and 0.05 ± 0.01, respectively). An increase in PME/tPh was observed in the ANIT_0.05% group only (0.17 ± 0.02) relative to PFC_0.05% (0.12 ± 0.01). Ex vivo (1)H MRS findings supported this, wherein measured phosphocholines (PCs) were increased in ANIT_0.05% and ANIT_0.04% groups. Increases in relative total choline (tCho) distinguished the ANIT_0.05% group from the ANIT_0.04% group. Markers of hepatotoxicity such as raised total bilirubin and alkaline phosphatase were found at all ANIT doses. Histological findings included a dose-related increase in both severity of biliary hyperplasia and focal hepatocellular necrosis. Here, we found that ANIT-induced moderate hepatobiliary dysfunction was associated with a relative increase in phosphodiesters in vivo and PCs ex vivo. Raised PME/tPh in vivo and tCho ex vivo were also present at high doses corresponding to a higher incidence of marked biliary hyperplasia and moderate hepatocellular necrosis.

Environmental contaminant mixtures at ambient concentrations invoke a metabolic stress response in goldfish not predicted from exposure to individual compounds alone

Environmental contaminants from wastewater and industrial or agricultural areas are known to have adverse effects on development, reproduction, and metabolism. However, reliable assessment of environmental contaminant impact at low (i.e., ambient) concentrations using genomics and transcriptomics approaches has proven challenging. A goldfish model was used to investigate the effects of aquatic pollutant exposure in vivo by means of quantitative nuclear magnetic resonance metabolomics in multiple organs to elucidate a system-wide response. Animals were exposed to 4,4'-isopropylidenediphenol (Bisphenol-A, BPA), di-(2-ethylhexyl)-phthalate (DEHP), and nonylphenol (NP). Metabolite-specific spectral analysis combined with pathway-driven bioinformatics indicated changes in energy and lipid metabolism in liver following exposure to individual contaminants and a tertiary mixture. A dissimilar response in testis exposed to DEHP and mixture indicates disrupted AMPK and cAMP signaling. Uniquely, our observations (1) suggest that exposure to a contaminant mixture is characterized by a stress response not predicted from exposure to individual contaminants, even in the absence of other phenotypic features and (2) demonstrate the sensitivity of metabolomics in risk-assessment of environmental toxicant mixtures at ambient concentrations by detecting early stage metabolic dysregulation. These findings have general applicability in the assessment of "benign" compound mixtures in environmental and pharmaceutical development.

Metabolic responses in gills of Manila clam Ruditapes philippinarum exposed to copper using NMR-based metabolomics

Copper is an important heavy metal contaminant with high ecological risk in the Bohai Sea. In this study, the metabolic responses in the bioindicator, Manila clam (Ruditapes philippinarum), to the environmentally relevant copper exposures were characterized using NMR-based metabolomics. The significant metabolic changes corresponding to copper exposures were related to osmolytes, intermediates of the Krebs cycle and amino acids, such as the increase in homarine, branched chain amino acids and decrease in succinate, alanine and dimethylamine in the copper-exposed clam gills during 96 h exposure period. Overall, Cu may lead to the disturbances in osmotic regulation and energy metabolism in clams during 96 h experimental period. These results demonstrate that NMR-based metabolomics is applicable for the discovery of metabolic biomarkers which could be used to elucidate the toxicological mechanisms of marine heavy metal contaminants.

A(1)H NMR-based metabonomic study on the SAMP8 and SAMR1 mice and the effect of electro-acupuncture

A (1)H NMR-based metabonomic method was used to investigate the metabolic change of plasma in senescence-prone 8 (SAMP8) mice before and after electro-acupuncture (EA). Sixteen SAMP8 male mice (aged 8 months) were randomly divided into model group and acupuncture treatment group while the later group received EA treatment for 21 days. Eight senescence-resistant 1 (SAMR1) mice were used as the control group. Morris water maze was used to evaluate the effects of EA. All mice plasma samples obtained from different groups were analyzed by using 600 MHz (1)H nuclear magnetic resonances ((1)H NMR) spectroscopy. The data sets were analyzed by Principal Components Analysis (PCA) and Partial Least Squares-Discriminant Analysis (PLS-DA) to discriminate the key plasma metabolites among different groups. Results indicated that both the escape and probe tasks of SAMP8 could be improved by EA treatment. Metabonomic study showed that SAMR1 and SAMP8 were separated clearly in both CPMG_OSC_PLS and LED _OSC_PLS score plots. Interestingly, samples obtained from EA group were distributed closely to SAMR1 group in CPMG_OSC_PLS score plot, but away from SAMP8 group in LED_OSC_PLS score plot. Corresponding loading plots showed that much less lactate was seen in SAMP8 mice plasma. Other changes including higher levels of dimethylamine (DMA) Choline and α-glucose but lower levels of leucine/isoleucine, HDL, LDL/VLDL, 3-Hydroxybutyrate (3-HB), and Trimethylamine N-oxide (TMAO) were observed in the SAMP8 mice plasma than in the SAMR1. After EA treatment, the levels of lactate, DMA, choline and TMAO were improved. Results of this work can provide valuable clues to the understanding of the metabolic changes in the senile impairment of mice. It is also hoped that the methodology can be used in evaluating the effects of EA and understanding the underlying acupuncture mechanism in treating neurodegenerative diseases.

Tissue-specific toxicological effects of cadmium in green mussels (Perna viridis): nuclear magnetic resonance-based metabolomics study

Toxicity tests for metals have traditionally focused on selected biomarkers to characterize the biological stress induced by metals in marine organisms. Here nuclear magnetic resonance (NMR)-based metabolomics, a system biology tool, was applied to the marine green mussel, Perna viridis, to investigate the toxicological effects of Cd in both digestive gland and adductor muscle tissues. After Cd exposure for either two or four weeks, there was no significant metabolic change in the mussels exposed to Cd at 2 µg/L. At 20 µg/L, there were major metabolite changes related to amino acids, osmolytes, and energy metabolites. Digestive gland tissue was more sensitive to Cd than adductor muscle tissue. The adductor muscle tissue showed elevated levels of glutamine, glutamate, and lactate, and reduced levels of branched chain amino acids, aspartate, phenylalanine, and tyrosine. Overall, four weeks of Cd exposure produced neurotoxicity and metabolic disturbances and disturbed osmoregulation. These results suggest that the adductor muscle tissue of mussels may be a suitable supplemental biomarker for exposure to toxicants. In addition, the results demonstrate that (1) H-NMR-based metabolomic analysis can provide a systematic view of the toxicological effects of metals on mussels, suggesting that it might be employed to investigate the toxicological effects of other marine pollutants.

Systems responses of rats to aflatoxin B1 exposure revealed with metabonomic changes in multiple biological matrices

Exposure to aflatoxins causes liver fibrosis and hepatocellular carcinoma posing a significant health risk for human populations and livestock. To understand the mammalian systems responses to aflatoxin-B1 (AFB1) exposure, we analyzed the AFB1-induced metabonomic changes in multiple biological matrices (plasma, urine, and liver) of rats using (1)H NMR spectroscopy together with clinical biochemistry and histopathologic assessments. We found that AFB1 exposure caused significant elevation of glucose, amino acids, and choline metabolites (choline, phosphocholine, and glycerophosphocholine) in plasma but reduction of plasma lipids. AFB1 also induced elevation of liver lipids, amino acids (tyrosine, histidine, phenylalanine, leucine, isoleucine, and valine), choline, and nucleic acid metabolites (inosine, adenosine, and uridine) together with reduction of hepatic glycogen and glucose. AFB1 further caused decreases in urinary TCA cycle intermediates (2-oxoglutarate and citrate) and elevation of gut microbiota cometabolites (phenylacetylglycine and hippurate). These indicated that AFB1 exposure caused hepatic steatosis accompanied with widespread metabolic changes including lipid and cell membrane metabolisms, protein biosynthesis, glycolysis, TCA cycle, and gut microbiota functions. This implied that AFB1 exposure probably caused oxidative-stress-mediated impairments of mitochondria functions. These findings provide an overview of biochemical consequences of AFB1 exposure and comprehensive insights into the metabolic aspects of AFB1-induced hepatotoxicity in rats.

High-resolution ¹H magic angle spinning NMR spectroscopy of intact Arctic char (Salvelinus Alpinus) muscle. Quantitative analysis of n-3 fatty acids, EPA and DHA

The lipid and small metabolite profiles from intact muscles of Arctic char were investigated using (1)H high-resolution magic angle spinning ((1)H HR-MAS) NMR spectroscopy. Not only the total n-3 fatty acid content but also the eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) contents of the muscle were obtained from the (1)H HR-MAS NMR spectra without pretreatment of the tissue or lipophilic extraction. A number of small metabolites could also be observed, where creatine/phosphocreatine, anserine and taurine were the most abundant. Thus, the use of (1)H HR-MAS NMR led to simplified analysis techniques that can give direct information on the nutritional value of the fish.