Taurine, a possible urinary marker of liver damage: a study of taurine excretion in carbon tetrachloride-treated rats

Traditional Chinese medicine Zhusha Anshen Wan: protective effects on liver, kidney, and intestine of the individual drugs using 1H NMR metabolomics

Introduction: Zhusha Anshen Wan (ZSASW) is a traditional Chinese medicine compound mainly composed of mineral drugs. In clinical practice, ZSASW did not show the toxicity of administering equal doses of cinnabar alone, suggesting that the four combination herbs in ZSASW can alleviate the damage of cinnabar. The effect of each herb on reducing the toxicity of cinnabar has not been fully explained. Methods: In our study, we utilized a metabonomics approach based on high-resolution 1H nuclear magnetic resonance spectroscopy to investigate the reduction of toxicity by each herb in ZSASW. Liver, kidney and intestinal histopathology examinations and biochemical analysis of the serum were also performed. Results: Partial least squares-discriminant analysis (PLS-DA) was conducted to distinct different metabolic profiles in the urine and serum from the rats. Liver and kidney histopathology examinations, as well as analysis of serum clinical chemistry analysis, were also carried out. The metabolic profiles of the urine and serum of the rats in the CGU (treated with cinnabar and Glycyrrhiza uralensis Fisch) and CCC (treated with cinnabar and Coptis chinensis French) groups were remarkably similar to those of the control group, while those of the CRG (treated with cinnabar and Rehmannia glutinosa Libosch) and CAS (treated with cinnabar and Angelica sinensis) groups were close to those of the cinnabar group. The metabolic profiles of the urine and serum of the rats in the CGU and CCC groups were remarkably similar to those of the control group, while those of the CRG and CAS groups were close to those of the cinnabar group. Changes in endogenous metabolites associated with toxicity were identified. Rehmannia glutinosa, Rhizoma Coptidis and Glycyrrhiza uralensis Fisch could maintain the dynamic balance of the intestinal flora. These results were also verified by liver, kidney and intestinal histopathology examinations and biochemical analysis of the serum. The results suggested that Discussion: The metabolic mechanism of single drug detoxification in compound prescriptions has been elucidated. Coptis chinensis and Glycyrrhiza uralensis serve as the primary detoxification agents within ZSASW for mitigating liver, kidney, and intestinal damage caused by cinnabar. Detoxification can be observed through changes in the levels of various endogenous metabolites and related metabolic pathways.

Urinary 1H NMR Metabolomic Analysis of Prenatal Maternal Stress Due to a Natural Disaster Reveals Metabolic Risk Factors for Non-Communicable Diseases: The QF2011 Queensland Flood Study

Prenatal stress alters fetal programming, potentially predisposing the ensuing offspring to long-term adverse health outcomes. To gain insight into environmental influences on fetal development, this QF2011 study evaluated the urinary metabolomes of 4-year-old children (n = 89) who were exposed to the 2011 Queensland flood in utero. Proton nuclear magnetic resonance spectroscopy was used to analyze urinary metabolic fingerprints based on maternal levels of objective hardship and subjective distress resulting from the natural disaster. In both males and females, differences were observed between high and low levels of maternal objective hardship and maternal subjective distress groups. Greater prenatal stress exposure was associated with alterations in metabolites associated with protein synthesis, energy metabolism, and carbohydrate metabolism. These alterations suggest profound changes in oxidative and antioxidative pathways that may indicate a higher risk for chronic non-communicable diseases such obesity, insulin resistance, and diabetes, as well as mental illnesses, including depression and schizophrenia. Thus, prenatal stress-associated metabolic biomarkers may provide early predictors of lifetime health trajectories, and potentially serve as prognostic markers for therapeutic strategies in mitigating adverse health outcomes.

Lipidized PrRP Analog Exhibits Strong Anti-Obesity and Antidiabetic Properties in Old WKY Rats with Obesity and Glucose Intolerance

Prolactin-releasing peptide (PrRP) is an anorexigenic neuropeptide that has potential for the treatment of obesity and its complications. Recently, we designed a palmitoylated PrRP31 analog (palm¹¹-PrRP31) that is more stable than the natural peptide and able to act centrally after peripheral administration. This analog acted as an anti-obesity and glucose-lowering agent, attenuating lipogenesis in rats and mice with high-fat (HF) diet-induced obesity. In Wistar Kyoto (WKY) rats fed a HF diet for 52 weeks, we explored glucose intolerance, but also prediabetes, liver steatosis and insulin resistance-related changes, as well as neuroinflammation in the brain. A potential beneficial effect of 6 weeks of treatment with palm¹¹-PrRP31 and liraglutide as comparator was investigated. Liver lipid profiles, as well as urinary and plasma metabolomic profiles, were measured by lipidomics and metabolomics, respectively. Old obese WKY rats showed robust glucose intolerance that was attenuated by palm¹¹-PrRP31, but not by liraglutide treatment. On the contrary, liraglutide had a beneficial effect on insulin resistance parameters. Despite obesity and prediabetes, WKY rats did not develop steatosis owing to HF diet feeding, even though liver lipogenesis was enhanced. Plasma triglycerides and cholesterol were not increased by HFD feeding, which points to unincreased lipid transport from the liver. The liver lipid profile was significantly altered by a HF diet that remained unaffected by palm¹¹-PrRP31 or liraglutide treatment. The HF-diet-fed WKY rats revealed astrogliosis in the brain cortex and hippocampus, which was attenuated by treatment. In conclusion, this study suggested multiple beneficial anti-obesity-related effects of palm¹¹-PrRP31 and liraglutide in both the periphery and brain.

Taurine in Septic Critically Ill Patients: Plasma versus Blood

Purpose: Sepsis and systemic inflammatory response syndrome (SIRS) encompass various problems throughout the body, and two of its major problems are the creation of oxidative substances in the body and decrease of the body's antioxidant capacity to deal with the stress and organ damage. Optimal enteral nutrition fortified with antioxidant or immunomodulator amino acid is a hot topic concerning sepsis in the critical care setting. Taurine plays a protective role as an antioxidant in cells that is likely to have a protective role in inflammation and cytotoxicity. Methods: In the present study, 20 septic patients and 20 healthy volunteers were enrolled. The blood and plasma taurine levels of the patients on days 1, 3 and 7 were measured. Blood and plasma taurine level and the correlation between them, organ failure, and severity of the disease were assessed. Results: Taurine concentrations in the plasma of the septic patients were significantly lower than control group, and the whole blood concentrations were significantly higher than those of the control group (P<0.001). There was not a significant correlation between the blood and plasma taurine levels in control and septic patients. In addition, there was not any correlation between the severity of the disease, organ failure, mortality, and plasma as well as the blood concentration of taurine. Conclusion: In septic patients, taurine concentration in plasma and blood are low and high, respectively. These concentrations are not linked to each other and not associated with the patients' outcome, and the disease severity, and organ failure.

Glucagon-like peptide-1 analog liraglutide leads to multiple metabolic alterations in diet-induced obese mice

Liraglutide, a glucagon-like peptide-1 analog, has beneficial metabolic effects in patients with type 2 diabetes and obesity. Although the high efficacy of liraglutide as an anti-diabetic and anti-obesity drug is well known, liraglutide-induced metabolic alterations in diverse tissues remain largely unexplored. Here, we report the changes in metabolic profiles induced by a 2-week subcutaneous injection of liraglutide in diet-induced obese mice fed a high-fat diet for 8 weeks. Our comprehensive metabolomic analyses of the hypothalamus, plasma, liver, and skeletal muscle showed that liraglutide intervention led to various metabolic alterations in comparison with diet-induced obese or nonobese mice. We found that liraglutide remarkably coordinated not only fatty acid metabolism in the hypothalamus and skeletal muscle but also amino acid and carbohydrate metabolism in plasma and liver. Comparative analyses of metabolite dynamics revealed that liraglutide rewired intertissue metabolic correlations. Our study points to a previously unappreciated metabolic alteration by liraglutide in several tissues, which may underlie its therapeutic effects within and across the tissues.

Investigation of urinary metabolomics in a phase I hookworm vaccine trial in Gabon

Metabolomics provides a powerful tool to study physiological changes in response to various perturbations such as vaccination. We explored whether metabolomic changes could be seen after vaccination in a phase I trial where Gabonese adults living either in rural or semi-urban areas received the subunit hookworm vaccine candidates (Na-GST-1 and Na-APR-1 (M74) adjuvanted with Alhydrogel plus GLA-AF (n = 24) or the hepatitis B vaccine (n = 8) as control. Urine samples were collected and assayed using targeted ¹H NMR spectroscopy. At baseline, a set of metabolites significantly distinguished rural from semi-urban individuals. The pre- and post-vaccination comparisons indicated significant changes in few metabolites but only one day after the first vaccination. There was no relationship with immunogenicity. In conclusion, in a small phase 1 trial, urinary metabolomics could distinguish volunteers with different environmental exposures and reflected the safety of the vaccines but did not show a relationship to immunogenicity.

Taurine as a Natural Antioxidant: From Direct Antioxidant Effects to Protective Action in Various Toxicological Models

Natural antioxidants have received tremendous attention over the last 3 decades. At the same time, the attitude to free radicals is slowly changing, and their signalling role in adaptation to stress has recently received a lot of attention. Among many different antioxidants in the body, taurine (Tau), a sulphur-containing non-proteinogenic β-amino acid, is shown to have a special place as an important natural modulator of the antioxidant defence networks. Indeed, Tau is synthesised in most mammals and birds, and the Tau requirement is met by both synthesis and food/feed supply. From the analysis of recent data, it could be concluded that the direct antioxidant effect of Tau due to scavenging free radicals is limited and could be expected only in a few mammalian/avian tissues (e.g., heart and eye) with comparatively high (>15-20 mM) Tau concentrations. The stabilising effects of Tau on mitochondria, a prime site of free radical formation, are characterised and deserve more attention. Tau deficiency has been shown to compromise the electron transport chain in mitochondria and significantly increase free radical production. It seems likely that by maintaining the optimal Tau status of mitochondria, it is possible to control free radical production. Tau's antioxidant protective action is of great importance in various stress conditions in human life, and is related to commercial animal and poultry production. In various in vitro and in vivo toxicological models, Tau showed AO protective effects. The membrane-stabilizing effects, inhibiting effects on ROS-producing enzymes, as well as the indirect AO effects of Tau via redox balance maintenance associated with the modulation of various transcription factors (e.g., Nrf2 and NF-κB) and vitagenes could also contribute to its protective action in stress conditions, and thus deserve more attention.

Metabolomic Study of Obesity and Its Treatment with Palmitoylated Prolactin-Releasing Peptide Analog in Spontaneously Hypertensive and Normotensive Rats

In this study, the combination of metabolomics and standard biochemical and biometric parameters was used to describe the metabolic effects of diet-induced obesity and its treatment with the novel antiobesity compound palm¹¹-PrRP31 (palmitoylated prolactin-releasing peptide) in spontaneously hypertensive rats (SHR) and normotensive Wistar Kyoto rats (WKY). The results showed that SHR on a high-fat (HF) diet were normoglycemic with obesity and hypertension, while WKY on the HF diet were normotensive and obese with prediabetes. NMR-based metabolomics revealed mainly several microbial cometabolites altered by the HF diet, particularly in urine. The HF diet induced similar changes in both models. However, two groups of genotype-specific metabolites were defined: metabolites specific to the genotype at baseline (e.g., 1-methylnicotinamide, phenylacetylglycine, taurine, methylamine) and metabolites reacting specifically to the HF diet in individual genotypes (2-oxoglutarate, dimethylamine, N-butyrylglycine, p-cresyl sulfate). The palm¹¹-PrRP31 lowered body weight and improved biochemical and biometric parameters in both strains, and it improved glucose tolerance in WKY rats on the HF diet. In urine, the therapy induced significant decrease of formate and 1-methylnicotinamide in SHR and alanine, allantoin, dimethylamine, and N-butyrylglycine in WKY. Altogether, our study confirms the effectiveness of palm¹¹-PrRP31 for antiobesity treatment.

Taurine Enhances the Protective Actions of Fish Oil Against D-Galactosamine-Induced Metabolic Changes and Hepatic Lipid Accumulation and Injury in the Rat

This study has evaluated the effects of a supplementation with taurine (TAU) on the actions of fish oil (FO) against the hypoglycemia, hypoproteinemia, and hepatic accumulation of lipids and liver damage caused by D-galactosamine (GAL) in the rat. To this end, male Sprague-Dawley rats (200-225 g), in groups of 6, were orally treated with physiological saline (2.5 mL, control group), FO (60 mg/kg), TAU (2.4 mmol/kg) or FO-TAU for three consecutive days and before a single oral dose of GAL (400 mg/kg) given on day 3. In parallel, rats receiving only GAL on day 3 or N-acetylcysteine (NAC, 2.4 mmol/kg) for 3 days before GAL served as controls. On day 4 blood samples were collected by cardiac puncture and used to either measure glucose (GLC) or to obtain plasma fractions. Immediately thereafter, the livers were excised, made into a homogenate in phosphate buffered saline pH 7.4, and centrifuged to obtain clear supernatant. Plasma samples were assayed for their total protein (TP), triglycerides (TG), cholesterol (CHOL), phospholipids (PLP), free fatty acids (FFA) and total bilirubin (TB) and direct bilirubin (DB) contents, and for the activities of alanine transaminase (ALT), aspartate transaminase (AST) and alkaline phosphatase (ALP). The liver homogenates were used to measure TG, CHOL, PLP and total lipids (TL) contents. Without exceptions, GAL was found to markedly affect (p < 0.001) all of the experimental parameters examined, with increases occurring in all instances except for the values of the plasma GLC, TP and PLP which were decreased. A pretreatment with either FO or TAU led to significant attenuation of the effects of GAL and which, in most cases, were of similar magnitude. On the other hand, a combined pretreatment with FO plus TAU usually resulted in a greater protection than with either agent alone (p ≤ 0.05). NAC, serving as a reference treatment, was, in most instances, equipotent with FO alone and. in addition, was the only agent that significantly attenuated the increases in both liver weight and liver weight to body weight ratio caused by GAL.

¹H-NMR-Based Metabonomics of the Protective Effect of Coptis chinensis and Berberine on Cinnabar-Induced Hepatotoxicity and Nephrotoxicity in Rats

Coptis chinensis Franch has been used in Traditional Chinese Medicine (TCM) for treating infectious and inflammatory diseases for over two thousand years. Berberine (BN), an isoquinoline alkaloid, is the main component of Coptis chinensis. The pharmacological basis for its therapeutic effects, which include hepatoprotective effects on liver injuries, has been studied intensively, yet the therapy of liver injuries and underlying mechanism remain unclear. We investigated the detoxification mechanism of Coptis chinensis and berberine using metabolomics of urine and serum in the present study. After the treatment with Coptis chinensis and berberine, compared with the cinnabar group, Coptis chinensis and berberine can regulate the concentration of the endogenous metabolites. PLS-DA score plots demonstrated that the urine and serum metabolic profiles in rats of the Coptis chinensis and berberine groups were similar those of the control group, yet remarkably apart from the cinnabar group. The mechanism may be related to the endogenous metabolites including energy metabolism, amino acid metabolism and metabolism of intestinal flora in rats. Meanwhile, liver and kidney histopathology examinations and serum clinical chemistry analysis verified the experimental results of metabonomics.

Impact of novel palmitoylated prolactin-releasing peptide analogs on metabolic changes in mice with diet-induced obesity

Analogs of anorexigenic neuropeptides, such as prolactin-releasing peptide (PrRP), have a potential as new anti-obesity drugs. In our previous study, palmitic acid attached to the N-terminus of PrRP enabled its central anorexigenic effects after peripheral administration. In this study, two linkers, γ-glutamic acid at Lys¹¹ and a short, modified polyethylene glycol at the N-terminal Ser and/or Lys¹¹, were applied for the palmitoylation of PrRP31 to improve its bioavailability. These analogs had a high affinity and activation ability to the PrRP receptor GPR10 and the neuropeptide FF2 receptor, as well as short-term anorexigenic effect similar to PrRP palmitoylated at the N-terminus. Two-week treatment with analogs that were palmitoylated through linkers to Lys¹¹ (analogs 1 and 2), but not with analog modified both at the N-terminus and Lys¹¹ (analog 3) decreased body and liver weights, insulin, leptin, triglyceride, cholesterol and free fatty acid plasma levels in a mouse model of diet-induced obesity. Moreover, the expression of uncoupling protein-1 was increased in brown fat suggesting an increase in energy expenditure. In addition, treatment with analogs 1 and 2 but not analog 3 significantly decreased urinary concentrations of 1-methylnicotinamide and its oxidation products N-methyl-2-pyridone-5-carboxamide and N-methyl-4-pyridone-3-carboxamide, as shown by NMR-based metabolomics. This observation confirmed the previously reported increase in nicotinamide derivatives in obesity and type 2 diabetes mellitus and the effectiveness of analogs 1 and 2 in the treatment of these disorders.

Metabolic Profiling Analysis of the Alleviation Effect of Treatment with Baicalin on Cinnabar Induced Toxicity in Rats Urine and Serum

Objectives: Baicalin is the main bioactive flavonoid constituent isolated from Scutellaria baicalensis Georgi. The mechanisms of protection of liver remain unclear. In this study, ¹H NMR-based metabonomics approach has been used to investigate the alleviation effect of Baicalin.

Method:¹H NMR metabolomics analyses of urine and serum from rats, was performed to illuminate the alleviation effect of Baicalin on mineral medicine (cinnabar)-induced liver and kidney toxicity.

Results: The metabolic profiles of groups receiving Baicalin at a dose of 80 mg/kg were remarkably different from cinnabar, and meanwhile, the level of endogenous metabolites returned to normal compared to group cinnabar. PLS-DA scores plots demonstrated that the variation tendency of control and Baicalein are apart from Cinnabar. The metabolic profiles of group Baicalein were similar to those of group control. Statistics results were confirmed by the histopathological examination and biochemical assay.

Conclusion: Baicalin have the alleviation effect to the liver and kidney damage induced by cinnabar. The Baicalin could regulate endogenous metabolites associated with the energy metabolism, choline metabolism, amino acid metabolism, and gut flora.

The effects of liraglutide in mice with diet-induced obesity studied by metabolomics

Liraglutide is the glucagon-like peptide-1 receptor agonist widely used for the treatment of type 2 diabetes mellitus. Recently, it has been demonstrated to decrease cardiovascular morbidity and mortality in patients with type 2 diabetes and high cardiovascular risk. Although the major modes of liraglutide action are well-known, its detailed action at the metabolic level has not been studied. To this end, we explored the effect of 2-week liraglutide treatment in C57BL/6 male mice with obesity and diabetes induced by 13 weeks of high-fat diet using NMR spectroscopy to capture the changes in urine metabolic profile induced by the therapy. The liraglutide treatment decreased body and fat pads weight along with blood glucose and triglyceride levels. NMR spectroscopy identified 11 metabolites significantly affected by liraglutide treatment as compared to high-fat diet-fed control group. These metabolites included ones involved in nicotinamide adenine dinucleotide metabolism, β-oxidation of fatty acids and microbiome changes. Although majority of the metabolites changed after liraglutide treatment were similar as the ones previously identified after vildagliptin administration in a similar mouse model, the changes in creatinine, taurine and trigonelline were specific for liraglutide administration. The significance of these changes and its possible use in the personalization of antidiabetic therapy in humans requires further research.

Novel protective role of curcumin and taurine combination against experimental hepatocarcinogenesis

Hepatocarcinogenesis is a prerequisite to hepatocellular carcinoma (HCC), which is one of the most common cancers among humans. Therefore, it is important to search for agents that protect against hepatocarcinogenesis. The present study aimed to investigate the protective effects of a combination of taurine and curcumin against experimental hepatocarcinogenesis induced by diethyl nitrosamine (DENA) in a rat model. A total of 100 rats were divided into eight groups. Eight weeks following DENA injection and treatment with curcumin and taurine, the rats were sacrificed to obtain blood and hepatic tissue samples for the evaluation of various markers and histopathological observations. Serum levels of interleukin-2 (IL-2), interferon-γ (IFN-γ), α-fetoprotein (AFP) and α-L-fucosidase (AFU) were determined. Rats injected with DENA for eight weeks showed a high percentage of malignant changes in hepatic tissues, as well as a significant increases in the serum levels of AFP and AFU and significant reductions in the serum levels of IL-2 and IFN-γ. Treatment with curcumin and taurine markedly reduced the extent of malignant changes in the rat liver tissues, with their liver tissues showing patterns similar to that of the normal control rats. In addition, this combination resulted in normal serum levels of IL-2, IFN-γ, AFP and AFU. The results of the present study suggested that a combination of curcumin and taurine may be a novel prophylactic agent against hepatocarcinogenesis in high-risk groups exposed to chemical hepatocarcinogens.

Metabolomics reveals the protective of Dihydromyricetin on glucose homeostasis by enhancing insulin sensitivity

Dihydromyricetin (DMY), an important flavanone found in Ampelopsis grossedentata, possesses antioxidative properties that ameliorate skeletal muscle insulin sensitivity and exert a hepatoprotective effect. However, little is known about the effects of DMY in the context of high-fat diet (HFD)-induced hepatic insulin resistance. Male Sprague-Dawley(SD) rats were fed a HFD(60% fat) supplemented with DMY for 8 weeks. The administration of DMY to the rats with HFD-induced insulin resistance reduces hyperglycemia, plasma levels of insulin, and steatosis in the liver. Furthermore, DMY treatment modulated 24 metabolic pathways, including glucose metabolism, the TCA cycle. DMY significantly enhanced glucose uptake and improved the translocation of glucose transporter 1. The specificity of DMY promoted the phosphorylation of AMP-activated protein kinase (AMPK). In addition, the exposure of HepG2 cells to high glucose concentrations impaired the insulin-stimulated phosphorylation of Akt2 Ser474 and insulin receptor substrate-1 (IRS-1) Ser612, increased GSK-3β phosphorylation, and upregulated G6Pase and PEPCK expression. Collectively, DMY improved glucose-related metabolism while reducing lipid levels in the HFD-fed rats. These data suggest that DMY might be a useful drug for use in type 2 diabetes insulin resistance therapy and for the treatment of hepatic steatosis.

Intervention effects of puerarin on blood stasis in rats revealed by a (1)H NMR-based metabonomic approach

Puerarin possesses a wide spectrum of biological activities including ameliorating effects on blood stasis, but the definite mechanism of this effect is still not known. In this study, a (1)H NMR-based plasma and urinary metabonomic approach was applied to comprehensively and holistically investigate the therapeutic effects of puerarin on blood stasis and its underlying mechanisms. Puerarin was injected intraperitoneally once daily for consecutive 7 days. The blood stasis rat model was established by placing the rats in ice-cold water during the time interval between two injections of adrenaline. With pattern recognition analysis, a clear separation of blood stasis model group and healthy control group was achieved and puerarin pretreatment group was located much closer to the control group than the model group, which was consistent with results of hemorheology studies. 15 and 10 potential biomarkers associated with blood stasis in plasma and urine, respectively, which were mainly involved in energy metabolism, lipid and membrane metabolisms, amino acid metabolism and gut microbiota metabolism, were identified. Puerarin could prevent blood stasis through partially regulating the disturbed metabolic pathways. This work highlights that metabonomics is a valuable tool for studying the essence of blood stasis as well as evaluating the efficacy of the corresponding drug treatment.

Gallic acid ameliorated impaired glucose and lipid homeostasis in high fat diet-induced NAFLD mice

Gallic acid (GA), a naturally abundant plant phenolic compound in vegetables and fruits, has been shown to have potent anti-oxidative and anti-obesity activity. However, the effects of GA on nonalcoholic fatty liver disease (NAFLD) are poorly understood. In this study, we investigated the beneficial effects of GA administration on nutritional hepatosteatosis model by a more “holistic view” approach, namely ¹H NMR-based metabolomics, in order to prove efficacy and to obtain information that might lead to a better understanding of the mode of action of GA. Male C57BL/6 mice were placed for 16 weeks on either a normal chow diet, a high fat diet (HFD, 60%), or a high fat diet supplemented with GA (50 and 100 mg/kg/day, orally). Liver histopathology and serum biochemical examinations indicated that the daily administration of GA protects against hepatic steatosis, obesity, hypercholesterolemia, and insulin resistance among the HFD-induced NAFLD mice. In addition, partial least squares discriminant analysis scores plots demonstrated that the cluster of HFD fed mice is clearly separated from the normal group mice plots, indicating that the metabolic characteristics of these two groups are distinctively different. Specifically, the GA-treated mice are located closer to the normal group of mice, indicating that the HFD-induced disturbances to the metabolic profile were partially reversed by GA treatment. Our results show that the hepatoprotective effect of GA occurs in part through a reversing of the HFD caused disturbances to a range of metabolic pathways, including lipid metabolism, glucose metabolism (glycolysis and gluconeogenesis), amino acids metabolism, choline metabolism and gut-microbiota-associated metabolism. Taken together, this study suggested that a ¹H NMR-based metabolomics approach is a useful platform for natural product functional evaluation. The selected metabolites are potentially useful as preventive action biomarkers and could also be used to help our further understanding of the effect of GA in hepatosteatosis mice.

Taurine and liver diseases: a focus on the heterogeneous protective properties of taurine

Taurine (2-aminoethylsulfonic acid) has many physiological and pharmacological functions in most tissues. It is abundantly maintained in the liver by both endogenous biosynthesis and exogenous transport, but is decreased in liver diseases. In the hepatic lobule, there are heterogeneous differences in metabolism between the pericentral (PC) and periportal regions, and the distributions of the biosynthesis capacity and specific taurine transporter expression are predominantly in the PC region. In cases of depletion of hepatic taurine level, serious liver damages were observed in the PC region. Taurine has protective effects against xenobiotics-induced liver damages in the PC region, but not xenobiotics-induced PP region damages. The xenobiotics that injure the PC region are mainly catabolized by NADPH-dependent cytochrome P450 2E1 that is also predominantly expressed in the PC region. Taurine treatment seems to be a useful agent for CYP2E1-related liver diseases with predominant damages in the PC region.

¹H NMR-based metabonomic analysis of brain in rats of morphine dependence and withdrawal intervention

Metabolic consequences of morphine dependence and withdrawal intervention have not been well explored. In the present study, the metabolic changes in brain hippocampus, nucleus accumbens (NAc), prefrontal cortex (PFC) and striatum of rats with morphine dependence and withdrawal intervention were explored by using ¹H nuclear magnetic resonance coupled with principal component analysis, partial least squares and orthogonal signal correction analysis. We found that the concentrations of neurotransmitters including glutamate, glutamine and gamma-aminobutyric acid changed differentially in hippocampus, NAc, PFC and striatum after repeated morphine treatment. Significant changes were also found in a number of cerebral metabolites including N-acetyl aspartate (NAA), lactic acid, creatine, myo-inositol and taurine. These findings indicate the profound disturbances of energy metabolism, amino acid metabolism and neurotransmitters caused by chronic morphine treatment. Interestingly, morphine-induced changes in lactic acid, creatine and NAA were clearly reversed by intervention of methadone or clonidine. Our study provides a comprehensive understanding of the metabolic alteration associated with morphine addiction and withdrawal therapy, which may help to develop new pharmacotherapies.

Dysautonomia in autism spectrum disorder: case reports of a family with review of the literature

Case histories of a mother and her two children are reported. The mother was a recovered alcoholic. She and her two children, both of whom had symptoms that are typical of autistic spectrum disorder, had dysautonomia. All had intermittently abnormal erythrocyte transketolase studies indicating abnormal thiamine pyrophosphate homeostasis. Both children had unusual concentrations of urinary arsenic. All had symptomatic improvement with diet restriction and supplementary vitamin therapy but quickly relapsed after ingestion of sugar, milk, or wheat. The stress of a heavy metal burden, superimposed on existing genetic or epigenetic risk factors, may be important in the etiology of autism spectrum disorder when in combination. Dysautonomia has been associated with several diseases, including autism, without a common etiology. It is hypothesized that oxidative stress results in loss of cellular energy and causes retardation of hard wiring of the brain in infancy, affecting limbic system control of the autonomic nervous system.

Pharmacokinetics of oral taurine in healthy volunteers

Taurine, a sulfur-containing amino acid, is a normal constituent of the human diet. Little is known of the pharmacokinetics of taurine in man after oral administration. We studied the pharmacokinetics of 4 g taurine in eight healthy male volunteers (median age 27.5, range 22-45) following orally administration in the fasting state in the morning. Blood samples were taken at regular intervals and plasma taurine concentration was measured by a modified HPLC method. Data were subjected to noncompartmental analysis. Maximum plasma taurine concentration (C(max)) was measured at 1.5 ± 0.6 hr after administration as 86.1 ± 19.0 mg/L (0.69 ± 0.15 mmol). Plasma elimination half-life (T(1/2)) and the ratio of clearance/bioavailability (Cl/F) were 1.0 ± 0.3 hr and 21.1 ± 7.8 L/hr, respectively. Since taurine is occasionally used in therapeutics as a medicine, the pharmacokinetics and effects of oral taurine in healthy volunteers would be useful in the future studies of taurine in pharmacology and nutrition.

NMR-based metabolic profiling identifies biomarkers of liver regeneration following partial hepatectomy in the rat

Tissue injury and repair are often overlapping consequences of disease or toxic exposure, but are not often considered as distinct processes in molecular studies. To establish the systemic metabolic response to liver regeneration, the partial hepatectomy (PH) model has been studied in the rat by an integrated metabonomics strategy, utilizing (1)H NMR spectroscopy of urine, liver and serum. Male Sprague-Dawley rats were subjected to either surgical removal of approximately two-thirds of the liver, sham operated (SO) surgery, or no treatment (n = 10/group) and samples collected over a 7 day period. A number of urinary metabolic perturbations were observed in PH rats compared with SO and control animals, including elevated levels of taurine, hypotaurine, creatine, guanidinoacetic acid, betaine, dimethylglycine and bile acids. Serum betaine and creatine were also elevated after PH, while levels of triglyceride were reduced. In the liver, triglycerides, cholesterol, alanine and betaine were elevated after PH, while choline and its derivatives were reduced. Upon examining the dynamic pattern of urinary response (the 'metabolic trajectory'), several metabolites could be categorized into groups likely to reflect perturbations to different processes such as dietary intake or hepatic 1-carbon metabolism. Several of the urinary perturbations observed during the regenerative phase of the PH model have also been observed after exposure to liver toxins, indicating that hepatic regeneration may make a contribution to the systemic alterations in metabolism associated with hepatotoxicity. The observed changes in 1-carbon and lipid metabolism are consistent with the proposed role of these pathways in the activation of a regenerative response and provide further evidence regarding the utility of urinary NMR profiles in the detection of liver-specific pathology. Biofluid (1)H NMR-based metabolic profiling provides new insight into the role of metabolism of liver regeneration, and suggests putative biomarkers for the noninvasive monitoring of the regeneration process.

Taurine reduces the secretion of apolipoprotein B100 and lipids in HepG2 cells

Background

Higher concentrations of serum lipids and apolipoprotein B100 (apoB) are major individual risk factors of atherosclerosis and coronary heart disease. Therefore ameliorative effects of food components against the diseases are being paid attention in the affluent countries. The present study was undertaken to investigate the effect of taurine on apoB secretion and lipid metabolism in human liver model HepG2 cells.

Results

The results demonstrated that an addition of taurine to the culture media reduces triacylglycerol (TG)-mass in the cells and the medium. Similarly, cellular cholesterol-mass was decreased. Taurine inhibited the incorporation of [¹⁴C] oleate into cellular and medium TG, suggesting the inhibition of TG synthesis. In addition, taurine reduced the synthesis of cellular cholesterol ester and its secretion, suggesting the inhibition of acyl-coenzyme A:cholesterol acyltransferase activity. Furthermore, taurine reduced the secretion of apoB, which is a major protein component of very low-density lipoprotein.

Conclusion

This is a first report to demonstrate that taurine inhibits the secretion of apoB from HepG2 cells.

Radiation metabolomics. 1. Identification of minimally invasive urine biomarkers for gamma-radiation exposure in mice

Gamma-radiation exposure has both short- and long-term adverse health effects. The threat of modern terrorism places human populations at risk for radiological exposures, yet current medical countermeasures to radiation exposure are limited. Here we describe metabolomics for gamma-radiation biodosimetry in a mouse model. Mice were gamma-irradiated at doses of 0, 3 and 8 Gy (2.57 Gy/min), and urine samples collected over the first 24 h after exposure were analyzed by ultra-performance liquid chromatography-time-of-flight mass spectrometry (UPLC-TOFMS). Multivariate data were analyzed by orthogonal partial least squares (OPLS). Both 3- and 8-Gy exposures yielded distinct urine metabolomic phenotypes. The top 22 ions for 3 and 8 Gy were analyzed further, including tandem mass spectrometric comparison with authentic standards, revealing that N-hexanoylglycine and beta-thymidine are urinary biomarkers of exposure to 3 and 8 Gy, 3-hydroxy-2-methylbenzoic acid 3-O-sulfate is elevated in urine of mice exposed to 3 but not 8 Gy, and taurine is elevated after 8 but not 3 Gy. Gene Expression Dynamics Inspector (GEDI) self-organizing maps showed clear dose-response relationships for subsets of the urine metabolome. This approach is useful for identifying mice exposed to gamma radiation and for developing metabolomic strategies for noninvasive radiation biodosimetry in humans.

A gender-specific discriminator in Sprague–Dawley rat urine: The deployment of a metabolic profiling strategy for biomarker discovery and identification

The use of nuclear magnetic resonance (NMR) spectroscopy and liquid chromatography-mass spectrometry (LC-MS) as complementary analytical techniques for open metabolic profiling is illustrated in the context of defining urinary biochemical discriminators between male and female Sprague-Dawley rats. Subsequent to the discovery of a female-specific urinary discriminator by LC-MS, further LC, MS, and NMR methods have been applied in a coordinated effort to identify this urinary component. Thereafter, the biological relevance and context of the identified component, in this case a steroid metabolite, has been achieved. This approach will be deployed in future studies of disease, drug efficacy, and toxicity to discover and identify biologically relevant markers.

Is Taurine A Biomarker?

Taurine, a sulfur-containing amino acid present in high concentrations in mammals, plays an important role in several essential biological processes. Taurine is not incorporated into protein and is the most abundant free amino acid in the heart, retina, skeletal muscle, brain, and leukocytes. The ideal biomarker or biological measure should be reliable, reproducible, noninvasive, simple to perform, and inexpensive. Samples for biological measures should be easily obtained from physiological fluids such as blood or urine. Taurine levels in physiologic fluids have been useful for both diagnosing pathology and establishing a disease modifying therapy. In the specific case of taurine, it is important that patient information include nutritional supplementation as well as information on disease status and medications. Taurine has been measured in biological fluids due to the importance of this simple amino acid and its relative ease of determination. Taurine has been measured in animal models of disease as well as a variety of human conditions. However, it remains unclear how taurine should be used as a biomarker and in which situations this measurement would be a good prognostic or diagnostic indicator.

An hypothesis for a mechanism underlying hepatotoxin-induced hypercreatinuria

As part of a wider metabonomic investigation into the early detection and discrimination of site-specific hepatotoxicity, male Sprague-Dawley rats were dosed with the model hepatotoxins allyl formate, ethionine and alpha-naphthylisothiocyanate (ANIT). Urine samples collected pre- and post-dose were examined by (1)H nuclear magnetic resonance (NMR) spectroscopy and the toxin-induced changes in urinary taurine and creatine excretion were quantified. Hypertaurinuria and hypercreatinuria were observed following allyl formate dosing, hypertaurinuria with no change in creatine excretion was observed after ethionine dosing, and hypotaurinuria and hypercreatinuria were observed after ANIT dosing. These changes are indicative of different effects on liver and it has been previously suggested that some hepatotoxin-induced changes in urinary taurine excretion may be due to altered hepatic cysteine utilisation. A related hypothesis is now presented that would explain the selective hypercreatinuria in terms of increased cysteine synthesis.

Changes in urinary taurine and hypotaurine excretion after two-thirds hepatectomy in the rat

This study followed the time course of urinary taurine and hypotaurine excretion after two-thirds hepatectomy in rats. The excretion of both taurine and hypotaurine was elevated during 18 h following the hepatectomy, with maximal excretion during the first 6 h. Twelve and 24 h after partial hepatectomy, the hepatic hypotaurine concentration was increased but liver taurine did not differ significantly from controls. No changes were observed in hypotaurine and taurine concentrations of heart, kidney, lung, muscle tissue and spleen. We postulate that partial hepatectomy induces a rapid increase of hepatic (hypo)taurine synthesis from precursor amino acids. The increased (hypo)taurine concentrations spill over into urine.

Biomarkers in toxicology

The use of biomarkers in toxicology is becoming increasingly important. This article briefly reviews some of the aspects in an attempt to give an overall view of the field. Some of the new developments, particularly in relation to biomarkers of exposure and response, are mentioned. Specific DNA and protein adducts can now be used as biomarkers of the effective exposure so incorporating variations in environmental levels and individual disposition. Analysis of urinary metabolite profiles by NMR can highlight novel markers and allow recognition of patterns of metabolite changes as biomarkers of a toxic response. Novel urinary markers for liver and testicular dysfunction are discussed. Finally, the acetylator phenotype as a biomarker of susceptibility is described.

Modulation of taurine levels in the rat liver alters methylene dianiline hepatotoxicity

Methylene dianiline (DAPM) causes hepatic damage and bile duct necrosis in rats. This has been detected histologically and biochemically. The toxicity was dose related over the range 0-100 mg/kg but the dose response relationship showed a maximum at about 75-100 mg/kg. This was true for both histopathology and biochemical parameters of liver dysfunction. When animals were depleted of taurine using beta-alanine pretreatment, the toxicity of DAPM was increased. Conversely treatment of rats with taurine, significantly attenuated the rise in alanine transaminase (ALT). However depletion of taurine with guanidinoethanesulphonate (GES) attenuated rises in both transaminases. It is concluded that taurine may play a role in the toxicity of DAPM but that GES, although depleting taurine as does beta-alanine, causes additional effects such as increasing glutathione (GSH), perhaps leading to protection.

Urinary taurine as a non-invasive marker of aflatoxin B1-induced hepatotoxicity: success and failure

The usefulness of urinary taurine as a non-invasive measure of hepatotoxicity of aflatoxin B1 (AFB1) was evaluated: changes in urinary taurine were characterized in a dose-response, acute toxicity experiment and in two sub-chronic, low dose exposure experiments. Urine of young, male, F344 rats was collected for 4 days prior to, and for 3 days after, the treatment with AFB1. Rats received a single p.o. dose of 0, 0.25, 0.5, 1, 2 or 3 mg AFB1/kg body wt. A transient increase in urinary taurine was noted with doses of 1, 2 or 3 mg AFB1/kg. In two sub-chronic exposure experiments, rats were gavaged with 25 microg AFB1/day for 5 successive days per week for 1 or 2 weeks (approximately 0.25 mg/kg/day). In the first experiment, only a transient increase in urinary taurine during 5 successive doses of AFB1 was observed, while in the second experiment, urinary taurine rose continuously during the 2 weeks of the AFB1 treatment. An explanation for these differing results is not obvious. Urinary taurine appeared to be a useful, non-invasive marker when hepatotoxicity was extensive. Unfortunately, at the low doses of AFB1 (0.25-0.5 mg/kg) as used in carcinogenesis experiments (10 doses of 25 microg/rat), urinary taurine appeared to be an insensitive measure of hepatic damage.

Neuroactive amino acids in hepatic encephalopathy

There is abundant evidence to suggest that alterations of excitatory and inhibitory amino acids play a significant role in the pathogenesis of hepatic encephalopathy (HE) in both acute and chronic liver diseases. Brain glutamate concentrations are reduced in patients who died in hepatic coma as well as in experimental HE, astrocytic reuptake of glutamate is compromised in liver failure and postsynaptic glutamate receptors (both NMDA and non-NMDA subclasses) are concomitantly reduced in density. Recent studies in experimental acute liver failure suggest reduced capacity of the astrocytic glutamate transporter in this condition. Together, this data suggests that neuron-astrocytic trafficking of glutamate is impared in HE. Other significant alterations of neuroactive amino acids in HE include a loss of taurine from brain cells to extracellular space, a phenomenon which could relate both to HE and to brain edema in acute liver failure. Increased concentrations of benzodiazepine-like compounds have been reported in human and experimental HE. Clinical trials with the benzodiazepine antagonist flumazenil reveal a beneficial effect in some patients with HE; the mechanism responsible for this effect, however, remains to be determined.

Taurine in hepatic encephalopathy

Liver and brain are the major organs responsible for taurine synthesis. In both acute and chronic liver failure, brain taurine concentrations are decreased and, since taurine appears to be implicated in K+ and Ca2+ homeostasis in brain, such losses could contribute to the pathophysiology of hepatic encephalopathy. Furthermore, taurine concentrations in cerebrospinal fluid in experimental acute liver failure are increased early in the progression of encephalopathy and prior to the onset of cerebral edema, a potentially fatal complication of acute liver failure. These findings suggest an osmoregulatory role for taurine in brain in acute liver failure. Monitoring of cerebrospinal fluid taurine may be of prognostic value in this severe, frequently fatal disorder.

Changes in taurine as an indicator of hepatic dysfunction and biochemical perturbations. Studies in vivo and in vitro

We have shown that urinary taurine level may be used as a biomarker of pathological and biochemical lesions. Detection of changes in the urinary concentration of this low molecular weight metabolite indicates biochemical lesions which may also be associated with pathological damage. Hepatotoxic compounds such as CCl4, galactosamine and thioacetamide that cause hepatic necrosis and compounds such as hydrazine and ethionine that cause fatty liver all result in elevated urinary taurine levels in rats. However compounds which do not cause liver damage, such as cycloheximide, also raise urinary taurine levels. All of these substances are known to or are believed to inhibit protein synthesis. Conversely, compounds which increase protein synthesis, such as phenobarbital and clenbuterol, significantly decrease urinary taurine levels. Compounds which interfere with hepatic GSH synthesis will also change urinary taurine levels. Thus, depletion of GSH with diethyl maleate or phorone decreases urinary taurine whereas inhibition of GSH synthesis with compounds such as buthionine sulphoximine increases urinary taurine levels. In isolated hepatocytes in vitro, leakage of taurine occurs in response to cytotoxic compounds such as hydrazine and allyl alcohol. However, total taurine levels were increased by the hepatotoxicant CCl4. Taurine synthesis is decreased by depletion of GSH with allyl alcohol in isolated hepatocytes. Therefore taurine levels are an important potential biomarker for biochemical lesions induced by chemicals both in vivo and in vitro, in particular changes in protein and GSH synthesis.

Electrically-evoked release of taurine in the rat vas deferens: evidence for a purinoceptor-mediated effect

Release of taurine evoked by electrical stimulation (2700 pulses; 5 Hz; 10 mA unless stated otherwise) and its dependence on noradrenaline and ATP was studied in isolated, perifused rat vas deferens. Outflow of noradrenaline was also measured in some experiments. The basal outflow of taurine averaged 3.90 +/- 0.32 nmol/g tissue per min. Electrical stimulation increased the outflow to about 4 times basal values. The electrically-evoked overflow averaged 128.0 +/- 11.7 nmol/g. An increase in current strength to 40 mA increased the evoked overflow by about 50%. At either current strength, the evoked overflow of taurine (and noradrenaline) was abolished by tetrodotoxin. Ca(2+)-deprivation blocked the overflow of taurine elicited by 10 mA and increased the overflow elicited by 40 mA pulses (but abolished noradrenaline overflow under either condition). Neither prazosin nor pretreatment of the rats with reserpine reduced electrically-evoked overflow of taurine (although reserpine pretreatment abolished evoked noradrenaline overflow). Tyramine (100 mumols/l; 9 min) caused an overflow of taurine 36% of that caused by electrical stimulation (but an overflow of noradrenaline 3 times higher than that evoked by electrical stimulation). Exogenous noradrenaline (9 min) caused a concentration-dependent overflow of taurine with a maximal effect at 162 mumol/l, amounting to 33% of the electrically-evoked overflow. alpha,beta-Methylene ATP (19 mumols/l) elicited an overflow of taurine that faded despite continued exposure to the drug and amounted to 62% of the response to electrical stimulation. Thirty minutes after the start of application of alpha,beta-methylene ATP, electrically-evoked overflow of taurine was greatly reduced. Suramin (100 mumols/l) also reduced taurine overflow in response to electrical stimulation.(ABSTRACT TRUNCATED AT 250 WORDS)

Studies on the muscle toxicant 2,3,5,6-tetramethyl p-phenylenediamine: effects on various biomarkers including urinary creatine and taurine

The effect of the specific muscle toxicant, 2,3,5,6-tetramethyl p-phenylenediamine (TMPD), on urinary creatine and taurine, markers of testicular and liver dysfunction, respectively, has been investigated in male Sprague-Dawley rats. Damage to the gastrocnemius and soleus muscles was accompanied by a rise in serum creatine kinase (predominantly the muscle-specific isoenzyme, CK-MM), alanine aminotransferase (ALT) and aspartate aminotransferase (AST). Increases in serum alpha-hydroxybutyrate dehydrogenase (HBDH) and total lactate dehydrogenase (LDH) (mainly isoenzymes, LDH1 and LDH2), occurred but only minor damage to the heart and no rise in CK-MB, (heart muscle isoenzyme) was seen. Damage to stage XIV tubules in the testis was evident histologically after the highest dose. This was accompanied by an increase in LDH-C4 testis-specific isoenzyme and a decrease in serum testosterone. Apart from reduced serum albumin, no other serum parameters indicated liver damage and there was only slight liver steatosis in some animals at the highest dose. Urinary taurine was not significantly raised after any dose of TMPD, but there was a significant increase in urinary creatine after the highest dose. It can be concluded that in the presence of discrete muscle damage, the use of urinary taurine and urinary creatine as markers of liver and testicular dysfunction, respectively, is not confounded. However, a variety of different markers should be used in conjunction to fully delineate the tissue damage due to toxic chemicals.

Determination of taurine in biological samples and isolated hepatocytes by high-performance liquid chromatography with fluorimetric detection

A high-performance liquid chromatographic method with fluorimetric detection is described for the routine and selective determination of taurine in urine, serum, tissues and isolated hepatocytes. The preparation and use of ion-exchange resins to extract taurine from biological samples is included. Taurine was derivatised with o-phthalaldehyde/2-mercaptoethanol prior to injection onto a C18 column (LiChrospherR 100 RP-18, 5 microns, 125 x 4 mm I.D.). Isocratic elution of the adduct was carried out using NaH2PO4 (0.05 M, pH 5.4) in methanol and water (43:57, v/v). Homoserine was used as an internal standard to facilitate the standardisation and quantitation of samples and analysis was completed in 6 min with homoserine and taurine eluting after 3 and 4 min, respectively. The method will detect 0.5 pmol of taurine on the column. Appropriate dilutions of these biological samples enable these samples to be assayed on an autosampler, using the same standard curve. Concentrations of taurine in human, dog and rat urine, rat liver, serum and isolated hepatocytes are reported.

Effect of various non-hepatotoxic compounds on urinary and liver taurine levels in rats

Administration of compounds which alter protein synthesis or sulphur amino acid metabolism in rats results in changes in the excretion of urinary taurine. Treatment with diethylmaleate (DEM) or phorone, which will deplete glutathione (GSH), reduces taurine excretion, whereas treatment with buthionine sulphoximine (BSO), which will inhibit glutathione synthesis, increases taurine excretion. Treatment with cycloheximide, an inhibitor of protein synthesis, increases taurine excretion, whereas pretreatment with phenobarbital, which will increase protein synthesis, decreases taurine excretion. Administration of agents which damage organs other than the liver such as the kidney, heart and testes, does not increase urinary taurine.

Investigations into the effects of various hepatotoxic compounds on urinary and liver taurine levels in rats

The effect of various hepatotoxicants on urinary taurine and urinary creatine has been studied in the rat. Several hepatotoxic agents, carbon tetrachloride, thioacetamide, galactosamine and allyl alcohol which all caused hepatic necrosis (sometimes accompanied by steatosis), resulted in a rise in urinary taurine and in some cases creatine, when administered to rats. Ethionine and hydrazine also raised urinary taurine but caused only steatosis and did not raise urinary creatine. Therefore urinary taurine and possibly creatine may be useful markers of liver injury and dysfunction. Liver taurine levels were also affected by some of the hepatotoxicants but in those cases where there was a rise in urinary taurine this could not be accounted for by the loss in liver taurine. It is suggested that the increase in urinary taurine is partly due to changes in protein synthesis and hence in sulphur amino acid metabolism caused by hepatotoxic agents. However, bromobenzene did not increase urinary taurine and alpha-naphthylisothiocyanate and lithocholate caused reduced levels. It is suggested that this lack of increase in urinary taurine may be due to depletion of glutathione or interference with the biliary system.

The correlation between urinary and liver taurine levels and between pre-dose urinary taurine and liver damage

Analysis of data from several studies has shown that urinary taurine levels are highly significantly correlated with liver taurine concentration in control rats. Furthermore, urinary taurine levels measured before dosing with various hepatotoxic agents are significantly correlated with serum AST and ALT values measured after dosing with hepatotoxicants. That is, animals with low urinary taurine values and therefore low liver taurine concentrations tend to show greater hepatic damage. These data suggest that taurine may have a protective function in the liver.