Role of taurine in the pathogenesis of obesity

The Anti-Inflammatory Effect of Taurine on Cardiovascular Disease

Taurine is a non-protein amino acid that is expressed in the majority of animal tissues. With its unique sulfonic acid makeup, taurine influences cellular functions, including osmoregulation, antioxidation, ion movement modulation, and conjugation of bile acids. Taurine exerts anti-inflammatory effects that improve diabetes and has shown benefits to the cardiovascular system, possibly by inhibition of the renin angiotensin system. The beneficial effects of taurine are reviewed.

Pharmacokinetic and metabolomic analyses of Mangiferin calcium salt in rat models of type 2 diabetes and non-alcoholic fatty liver disease

Background

Non-alcoholic fatty liver is one of the most common comorbidities of diabetes. It can cause disturbance of glucose and lipid metabolism in the body, gradually develop into liver fibrosis, and even cause liver cirrhosis. Mangiferin has a variety of pharmacological activities, especially for the improvement of glycolipid metabolism and liver injury. However, its poor oral absorption and low bioavailability limit its further clinical development and application. The modification of mangiferin derivatives is the current research hotspot to solve this problem.

Methods

The plasma pharmacokinetic of mangiferin calcium salt (MCS) and mangiferin were monitored by HPLC. The urine metabolomics of MCS were conducted by UPLC-Q-TOF-MS.

Results

The pharmacokinetic parameters of MCS have been varied, and the oral absorption effect of MCS was better than mangiferin. Also MCS had a good therapeutic effect on type 2 diabetes and NAFLD rats by regulating glucose and lipid metabolism. Sixteen potential biomarkers had been identified based on metabolomics which were related to the corresponding pathways including Pantothenate and CoA biosynthesis, fatty acid biosynthesis, citric acid cycle, arginine biosynthesis, tryptophan metabolism, etc.

Conclusions

The present study validated the favorable pharmacokinetic profiles of MCS and the biochemical mechanisms of MCS in treating type 2 diabetes and NAFLD.

Effects of taurine on growth performance, antioxidant capacity, and lipid metabolism in broiler chickens

To investigate the effects of dietary taurine supplementation on growth performance, antioxidant status, and lipid metabolism in broilers, 384 male broilers (Arbor Acres, 1 D of age) were randomly allocated into 4 groups with 8 replicates of 8 birds. Dietary treatments were supplemented with taurine at the level of 0.00, 2.50, 5.00, and 7.50 g/kg of the diet (denoted as CON, TAU1, TAU2, TAU3, respectively). The BW gain from 1 to 21 D and from 22 to 42 D were all increased linearly (linear, P < 0.001) by taurine supplementation. Throughout the trial period, the highest BW gain and favorable gain-to-feed ratio were observed in the TAU2 group. Taurine supplementation increased the antioxidant enzyme activities and decreased (linear, P < 0.001) the content of malondialdehyde in both serum and the liver of broilers and alleviated oxidative damage through enhancing (P < 0.05) the hepatic genes expression of nuclear factor erythroid-2-related factor 2 (NRF2), glutathione peroxidase (GPX), and heme oxygenase-1 (HO-1). Correspondingly, in serum, the activities of hepatic lipase and total lipase were decreased linearly and quadratically (linear and quadratic, P < 0.001) with the increasing inclusion of taurine in the diet. Meanwhile, in serum, the content of triglycerides was significantly decreased (P < 0.05), and except for TAU3, the total cholesterol content was also significantly decreased (P < 0.05) by taurine supplementation. In addition, the hepatic content of triglycerides was significantly decreased (P < 0.05) in the TAU1 and TAU2 groups. Compared with the CON group, the hepatic genes expression of adenosine monophosphate-activated protein kinase alpha (AMPKα), silent 1, (SIRT1) and carnitine palmitoyltransferase 1 (CPT-1) were all increased (P < 0.05), and sterol regulatory element-binding protein-1 (SREBP-1) expression was decreased (P < 0.05) in the TAU2 group. These results indicated that taurine supplementation improved the growth performance, antioxidant capacity, and lipid metabolism of broilers.

Dietary taurine stimulates the hepatic biosynthesis of both bile acids and cholesterol in the marine teleost, tiger puffer (Takifugu rubripes)

Taurine (TAU) plays important roles in the metabolism of bile acids, cholesterol and lipids. However, little relevant information has been available in fish where TAU has been identified as a conditionally essential nutrient. The present study aimed to investigate the effects of dietary TAU on the metabolism of bile acids, cholesterol and lipids in tiger puffer, which is both an important aquaculture species and a good research model, having a unique lipid storage pattern. An 8-week feeding trial was conducted in a flow-through seawater system. Three experimental diets differed only in TAU level, that is, 1·7, 8·2 and 14·0 mg/kg. TAU supplementation increased the total bile acid content in liver but decreased the content in serum. TAU supplementation also increased the contents of total cholesterol and HDL-cholesterol in both liver and serum. The hepatic bile acid profile mainly includes taurocholic acid (94·48 %), taurochenodeoxycholic acid (4·17 %) and taurodeoxycholic acid (1·35 %), and the contents of all these conjugated bile acids were increased by dietary TAU. The hepatic lipidomics analysis showed that TAU tended to decrease the abundance of individual phospholipids and increase those of some individual TAG and ceramides. The hepatic mRNA expression study showed that TAU stimulated the biosynthesis of both bile acids and cholesterol, possibly via regulation of farnesoid X receptor and HDL metabolism. TAU also stimulated the hepatic expression of lipogenic genes. In conclusion, dietary TAU stimulated the hepatic biosynthesis of both bile acids and cholesterol and tended to regulate lipid metabolism in multiple ways.

The effects of taurine supplementation on glycemic control and serum lipid profile in patients with type 2 diabetes: a randomized, double-blind, placebo-controlled trial

Previous studies have suggested that taurine has hypoglycemic and hypolipidemic effects on experimental diabetic models. Therefore, this clinical trial was designed to explore the impacts of taurine supplementation on glycemic control and lipid profile in the patients with T2DM. This study was conducted on 45 patients with T2DM in Tabriz Sheikhor-raees Polyclinic and Imam-Reza Hospital Endocrine Center. Subjects were randomly divided into taurine and placebo groups. Accordingly, the taurine group (n = 23) received taurine 3000 mg/daily and the placebo group (n = 22) took crystalline microcellulose/daily for the duration of 8 weeks. At baseline and after the trial completion, fasting blood samples were obtained from the patients to assess the glycemic indicators and lipid profile. Independent t test, paired t test, Pearson's correlation, and analysis of covariance was used for analysis. At the end of the study, levels of FBS (p = 0.01), insulin (p = 0.01), HOMA-IR (p = 0.003), TC (p = 0.013), and LDL-C (p = 0.041) significantly decreased in the taurine group compared to the placebo group. In addition, there was no significant changes in HbA1c, triglyceride, HDL-C, anthropometric indicators or dietary intakes by passing 8 weeks from the intervention. In conclusion, the findings of the current study indicated that taurine supplementation (3000 mg/day) for 8 weeks could improve the glycemic indexes and lipid profiles including TC and LDL-C in the patients with T2DM.

Taurine Stimulates Thermoregulatory Genes in Brown Fat Tissue and Muscle without an Influence on Inguinal White Fat Tissue in a High-Fat Diet-Induced Obese Mouse Model

This study was conducted to investigate if taurine supplementation stimulates the induction of thermogenic genes in fat tissues and muscles and decipher the mechanism by which taurine exerts its anti-obesity effect in a mildly obese ICR (CD-1®) mouse model. Three groups of ICR mice were fed a normal chow diet, a high-fat diet (HFD), or HFD supplemented with 2% taurine in drinking water for 28 weeks. The expression profiles of various genes were analyzed by real time PCR in interscapular brown adipose tissue (BAT), inguinal white adipose tissue (iWAT), and the quadriceps muscles of the experimental groups. Genes that are known to regulate thermogenesis like PGC-1α, UCP-1, Cox7a1, Cox8b, CIDE-A, and β1-, β2-, and β3-adrenergic receptors (β-ARs) were found to be differentially expressed in the three tissues. These genes were expressed at a very low level in iWAT as compared to BAT and muscle. Whereas, HFD increased the expression of these genes. Taurine supplementation stimulated the expression of UCP-1, Cox7a1, and Cox8b in BAT and only Cox7a1 in muscle, while there was a decrease in iWAT. In contrast, fat deposition-related genes, monoamine oxidases (MAO)-A, and -B, and lipin-1, were decreased by taurine supplementation only in iWAT and not in BAT or muscle. In conclusion, the potential anti-obesity effects of taurine may be partly due to upregulated thermogenesis in BAT, energy metabolism of muscle, and downregulated fat deposition in iWAT.

Taurine Supplementation Increases Post-Exercise Lipid Oxidation at Moderate Intensity in Fasted Healthy Males

Based on the fact that taurine can increase lipid metabolism, the objective of the present study was to evaluate the effects of different doses of acute taurine supplementation on lipid oxidation levels in healthy young men after a single bout of fasting aerobic exercise. A double-blind, acute, and crossover study design was conducted. Seventeen men (age 24.8 ± 4.07y; BMI: 23.9 ± 2.57 kg/m²) participated in the present study. Different doses of taurine (TAU) (3 g or 6 g) or placebo were supplemented 90 min before a single bout of fasting aerobic exercise (on a treadmill at 60% of VO₂ max). The subjects performed three trials, and each one was separated by seven days. Blood samples were collected at baseline and after the exercise protocol of each test to analyze plasma levels of glycerol and taurine. Lipid and carbohydrate oxidation were determined immediately after exercise for 15 min by indirect calorimetry. We observed that TAU supplementation (6 g) increased lipid oxidation (38%) and reduced the respiratory coefficient (4%) when compared to the placebo (p < 0.05). However, no differences in lipid oxidation were observed between the different doses of taurine (3 g and 6 g). For glycerol concentrations, there were no differences between trials. Six grams of TAU supplementation 90 min before a single bout of aerobic exercise in a fasted state was sufficient to increase the lipid oxidation post-exercise in healthy young men.

Human urine 1H NMR metabolomics reveals alterations of protein and carbohydrate metabolism when comparing habitual Average Danish diet vs. healthy New Nordic diet

OBJECTIVES

The aim of this study was to investigate the alteration of the human urine metabolome by means of diet and to compare the metabolic effects of the nutritionally healthy New Nordic Diet (NND) with an Average Danish Diet (ADD). The NND was designed a decade ago by scientists and chefs, based on local and sustainable foods, including fish, shellfish, vegetables, roots, fruit, and berries. The NND has been proven to lower blood pressure, reduce glycemia, and lead to weight loss.

METHODS

The human urine metabolome was measured by untargeted proton nuclear magnetic resonance spectroscopy in samples from 142 centrally obese Danes (20-66 years old), randomized to consume the ADD or the NND. The resulting metabolomics data was processed and analyzed using advanced multivariate data analysis methods to reveal effects related to the design factors, including diet, season, sex, and changes in body weight.

RESULTS

Exploration of the nuclear magnetic resonance profiles revealed unique metabolite markers reflecting changes in protein and carbohydrate metabolism between the two diets. Glycine betaine, glucose, trimethylamine N-oxide and creatinine were increased in urine of the individuals following the NND compared with the ADD population, whereas relative concentrations of tartrate, dimethyl sulfone, and propylene glycol were decreased. Propylene glycol had a strong association with the homeostatic model assessment for insulin resistance in the NND group. The food intake biomarkers found in this study confirm the importance of these as tools for nutritional research.

CONCLUSIONS

Findings from this study provided new insights into the effects of a healthy diet on glycemia, reduction of inflammation, and weight loss among obese individuals, and alteration of the gut microbiota metabolism.

Regulation of taurine in OTA-induced apoptosis and autophagy

Ochratoxin A (OTA), one of the most deleterious mycotoxins, could cause a variety of toxicological effects especially nephrotoxicity in animals and humans. Taurine, a wide-distributed cytoprotective amino acid, plays an important role as a basic factor for maintaining cellular integrity homeostasis. However, the potential effect of taurine in OTA-induced nephrotoxicity remains unknown. In the present study, we demonstrated that OTA treatment at 4.0-8.0 μM increased apoptosis in PK-15 cells as shown by increased the ratio of apoptosis and protein expression of Bax and cleaved-caspase-3, decreased protein expression of Bcl-2. Meantime, OTA treatment triggered autophagy, as indicated by markedly increased the protein expression of LC3-II and fluorescence intensity of GFP-LC3 dots. Taurine supplementation decreased OTA-induced cytotoxicity and attenuated apoptosis as shown by the decreased Annexin V/PI staining and the decreased expression of apoptosis-related proteins including Bax and caspase-3. Meanwhile, taurine attenuated OTA-induced autophagy by decreased the protein expression of LC3-II and fluorescence intensity of GFP-LC3 dots to maintain cellular homeostasis. In conclusion, taurine treatment could alleviate OTA-induced apoptosis and inhibit the triggered autophagy in PK-15 cells. Our study provides supportive data for the potential roles of taurine in reducing OTA-induced renal toxicity.

1H-NMR based metabolomics reveals the nutrient differences of two kinds of freshwater fish soups before and after simulated gastrointestinal digestion

Soups show diverse health functions, which could be linked to their original nutrient profiles and metabolites derived from digestion. NMR spectroscopy is a robust and rapid method that unveils or identifies the chemical composition of food or food-derived metabolites. In the current study, the 1H-NMR spectroscopy approach was applied to identify the differences in metabolic profiling of two kinds of home-cooked freshwater fish soups (crucian carp and snakehead fish) before and after in vitro gastrointestinal digestion. The nutritional profiles of these soups were studied using the 1H-NMR method for the first time. Two metabolomics methods, PCA (Principal Component Analysis) and OPLS-DA (Orthogonal Partial Least Squares Discriminant Analysis), were used to analyze the data. On the whole, levels of amino acid metabolites such as valine (Val), tyrosine, choline, taurine (Tau) and glycine were higher in the crucian carp soup, whereas higher levels of fatty acids and unsaturated fatty acids were found in the snakehead soup. Furthermore, the high content of seven metabolites valine, leucine, EPA C20:5 (PUFA eicosapentaenoic acid), acetic acid, taurine, GPCho (phosphatidylcholine) and creatine showed an upward trend after simulated gastrointestinal digestion. The results demonstrate that the 1H-NMR metabolic profile of different fish soups can shed some light on our understanding of food functional properties and dietary therapy. Furthermore, changes of metabolites in digested fish soups could reveal information about chemical compounds which play important roles in the body.

Flavin-Containing Monooxygenase 1 Catalyzes the Production of Taurine from Hypotaurine

Taurine is one of the most abundant amino acids in mammalian tissues. It is obtained from the diet and by de novo synthesis from cysteic acid or hypotaurine. Despite the discovery in 1954 that the oxygenation of hypotaurine produces taurine, the identification of an enzyme catalyzing this reaction has remained elusive. In large part, this is due to the incorrect assignment, in 1962, of the enzyme as an NAD-dependent hypotaurine dehydrogenase. For more than 55 years, the literature has continued to refer to this enzyme as such. Here we show, both in vivo and in vitro, that the enzyme that oxygenates hypotaurine to produce taurine is flavin-containing monooxygenase (FMO) 1. Metabolite analysis of the urine of Fmo1-null mice by ¹H NMR spectroscopy revealed a buildup of hypotaurine and a deficit of taurine in comparison with the concentrations of these compounds in the urine of wild-type mice. In vitro assays confirmed that human FMO1 catalyzes the conversion of hypotaurine to taurine, utilizing either NADPH or NADH as cofactor. FMO1 has a wide substrate range and is best known as a xenobiotic- or drug-metabolizing enzyme. The identification that the endogenous molecule hypotaurine is a substrate for the FMO1-catalyzed production of taurine resolves a long-standing mystery. This finding should help establish the role FMO1 plays in a range of biologic processes in which taurine or its deficiency is implicated, including conjugation of bile acids, neurotransmitter, antioxidant and anti-inflammatory functions, and the pathogenesis of obesity and skeletal muscle disorders. SIGNIFICANCE STATEMENT: The identity of the enzyme that catalyzes the biosynthesis of taurine from hypotaurine has remained elusive. Here we show, both in vivo and in vitro, that flavin-containing monooxygenase 1 catalyzes the oxygenation of hypotaurine to produce taurine.

Glycine supplementation during six months does not alter insulin, glucose or triglycerides plasma levels in healthy rats

Nowadays, glycine is used in nutritional supplements and to attenuate chronic complications of diabetes and obesity; however, its use has side effects as insulin resistance. Our aim was to evaluate the effect of chronic glycine supplementation on insulin, glucose and triglyceride levels in healthy Wistar rats. Groups were: Control (C), that received sterilized water only, glycine (GG), that received 1% glycine and taurine (TG), that received 0.5% taurine during 6 months (n = 10). Our results showed no differences in plasma insulin levels after six months of supplementation (C: 13.22 ± 2.0; GG: 11.4 ± 2.0; TG: 11.13 ± 2.0 ng/ml; p = 0.64). Likewise, neither glucose plasma concentration (C: 99.9 ± 3.9 mg/dl; GG: 104.3 ± 4.3 mg/dl; TG: 104.5 ± 4.8 mg/dl) (p = 0.88) nor triglyceride levels (C: 58.4 ± 5.6 mg/dl; GG: 46.9 ± 2.3 mg/dl; TG: 50.68 ± 3.3 mg/dl), showed differences after six months supplementation (p = 0.22). Furthermore, the analysis of glycine (C: 80 ± 24.6; GG: 83.9 ± 25.9; TG: 90.7 ± 13.5 nmol/ml) (p = 0.19) and taurine (C: 169 ± 15.17; GG: 148.7 ± 23.9; TG: 165.8 ± 22.5 nmol/ml) (p = 0.4) in the plasma of animals with supplementation showed no significant changes. Additionally, general urine tests and histological analysis of liver or kidneys showed no alterations. In conclusion, chronic supplementation with 1% glycine did not have any significant detrimental side effects in our model. However, more studies are still necessary to evaluate the effect of 1% glycine supplementation in humans.

Patterns in metabolite profile are associated with risk of more aggressive prostate cancer: A prospective study of 3,057 matched case-control sets from EPIC

Metabolomics may reveal novel insights into the etiology of prostate cancer, for which few risk factors are established. We investigated the association between patterns in baseline plasma metabolite profile and subsequent prostate cancer risk, using data from 3,057 matched case-control sets from the European Prospective Investigation into Cancer and Nutrition (EPIC). We measured 119 metabolite concentrations in plasma samples, collected on average 9.4 years before diagnosis, by mass spectrometry (AbsoluteIDQ p180 Kit, Biocrates Life Sciences AG). Metabolite patterns were identified using treelet transform, a statistical method for identification of groups of correlated metabolites. Associations of metabolite patterns with prostate cancer risk (OR1SD ) were estimated by conditional logistic regression. Supplementary analyses were conducted for metabolite patterns derived using principal component analysis and for individual metabolites. Men with metabolite profiles characterized by higher concentrations of either phosphatidylcholines or hydroxysphingomyelins (OR1SD  = 0.77, 95% confidence interval 0.66-0.89), acylcarnitines C18:1 and C18:2, glutamate, ornithine and taurine (OR1SD  = 0.72, 0.57-0.90), or lysophosphatidylcholines (OR1SD  = 0.81, 0.69-0.95) had lower risk of advanced stage prostate cancer at diagnosis, with no evidence of heterogeneity by follow-up time. Similar associations were observed for the two former patterns with aggressive disease risk (the more aggressive subset of advanced stage), while the latter pattern was inversely related to risk of prostate cancer death (OR1SD  = 0.77, 0.61-0.96). No associations were observed for prostate cancer overall or less aggressive tumor subtypes. In conclusion, metabolite patterns may be related to lower risk of more aggressive prostate tumors and prostate cancer death, and might be relevant to etiology of advanced stage prostate cancer.

Metabolic profiling of acromegaly using a GC-MS-based nontargeted metabolomic approach

PURPOSE

Acromegaly is a rare disease caused by chronic hypersecretion of growth hormone, which leads to multiple comorbidities and reduced life expectancy. The objective of this study was to characterize the serum metabolic profiles of acromegaly patients and identify metabolic biomarkers using metabolomics.

METHODS

Twenty-nine active acromegaly patients and age- and sex-matched normal controls were recruited. Serum samples were collected, and serum metabolites were analyzed using gas chromatography-mass spectrometry coupled with a series of multivariate statistical analyses.

RESULTS

The orthogonal projections to latent structures-discriminate analysis (OPLS-DA) model identified and validated significant metabolic differences between individuals with acromegaly and normal controls (R²Y = 0.908 and Q²Y = 0.601). Compared with normal controls, acromegaly patients had elevated levels of 5-aminovaleric acid, glyceric acid, L-dithiothreitol, dihydrocoumarin, N-acetyl-L-glutamic acid, gluconic acid, and monoolein (P < 0.05) and reduced serum levels of D-erythronolactone, taurine, carbamoyl-aspartic acid, and mucic acid (P < 0.01). Furthermore, glyceric acid and taurine possessed higher area under the receiver operating characteristic curve values (AUC values, 0.914 and 0.931, respectively), suggesting an excellent clinical ability to distinguish acromegaly patients from normal controls. Pathway analysis revealed that the pentose phosphate pathway and the taurine and hypotaurine metabolic pathway are significant pathways (P = 0.002 and 0.004, respectively).

CONCLUSIONS

Metabolic activity is significantly altered in the serum of individuals with active acromegaly. Glyceric acid and taurine may be considered potential biomarkers for distinguishing acromegaly patients from normal controls.

The effects of taurine supplementation on oxidative stress indices and inflammation biomarkers in patients with type 2 diabetes: a randomized, double-blind, placebo-controlled trial

BACKGROUND

Reduced serum level of taurine in type 2 diabetes mellitus (T2DM) was shown to be associated with the metabolic alterations and clinical complications of diabetes. Dietary supplementation with taurine may attenuate oxidative stress and inflammatory responses in T2DM as well as alleviate diabetes-induced complications. Hence, this study evaluated the effect of taurine supplementation on oxidative stress and inflammatory biomarkers in patients with T2DM.

METHODS

Fifty patients with T2DM were randomly allocated to two groups to consume either taurine (containing 1000 mg taurine), or placebo (containing crystalline microcellulose) three times per day for 8 weeks. Anthropometric data, dietary intake, serum total antioxidant capacity (TAC), malondialdehyde (MDA), the activities of antioxidant enzymes superoxide dismutase (SOD) and catalase (CAT), serum levels of tumor necrosis factor alpha (TNF-α), interleukin 6 (IL-6) and high-sensitivity C-reactive protein (hs-CRP) were assessed before and after intervention.

RESULTS

There was a significant increase in SOD (5.1%, p = 0.004) and CAT (4.22%, p = 0.001) after 8 weeks of taurine supplementation. In addition, serum levels of MDA (26.33%, p = 0.001), hs-CRP (16.01%, p = 0.001), and TNF-α (11.65%, p = 0.03) significantly decreased in the taurine group compared with baseline. Following treatment, the taurine group had fewer serum levels of MDA (p = 0.04), hs-CRP (p = 0.002) and TNF-α (p = 0.006) than the placebo group. Also, a significant increase was observed in SOD (p = 0.007), and CAT (p = 0.001) in the taurine group compared with the placebo group. There were no differences in the serum levels of IL-6 or TAC.

CONCLUSIONS

The findings of this study showed that taurine supplementation improved some oxidative stress indices and inflammatory biomarkers in patients with T2DM.Trial registration The protocol of this clinical trial is registered with the Iranian Registry of Clinical Trials (http://www.IRCT.IR, identifier: IRCT20121028011288N16).

Taurine inhibits neuron apoptosis in hippocampus of diabetic rats and high glucose exposed HT-22 cells via the NGF-Akt/Bad pathway

Type 2 Diabetes causes learning and memory deficits that might be mediated by hippocampus neuron apoptosis. Studies found that taurine might improve cognitive deficits under diabetic condition because of its ability to prevent hippocampus neuron apoptosis. However, the effect and mechanism is not clear. In this study, we explore the effect and mechanism of taurine on inhibiting hippocampus neuron apoptosis. Sixty male Sprague-Dawley rats were randomly divided into control, T2D, taurine treatment (giving 0.5%, 1%, and 2% taurine in drinking water) groups. Streptozotocin was used to establish the diabetes model. HT-22 cell (hippocampus neurons line) was used for in vitro experiments. Morris Water Maze test was used to check the learning and memory ability, TUNEL assay was used to measure apoptosis and nerve growth factor (NGF); Akt/Bad pathway relevant protein was detected by western blot. Taurine improved learning and memory ability and significantly decreased apoptosis of the hippocampus neurons in T2D rats. Moreover, taurine supplement also inhibited high glucose-induced apoptosis in HT-22 cell in vitro. Mechanistically, taurine increased the expression of NGF, phosphorylation of Trka, Akt, and Bad, as well as reduced cytochrome c release from mitochondria to cytosol. However, beneficial effects of taurine were blocked in the presence of anti-NGF antibody or Akt inhibitor. Taurine could inhibit hippocampus neuron apoptosis via NGF-Akt/Bad pathway. These results provide some clues that taurine might be efficient and feasible candidate for improvement of learning and memory ability in T2D rats.

Shape-dependent toxicity of alumina nanoparticles in rat astrocytes

Nanosized alumina (Al₂O₃-NPs), a widely used nanoparticle in numerous commercial applications, is released into environment posing a threat to the health of wildlife and humans. Recent research has revealed essential roles of physicochemical properties of nanoparticles in determining their toxicity potencies. However, influence of shape on neurotoxicity induced by heterogeneous Al₂O₃-NPs remains unknown. We herein compared the neurotoxicity of two shapes of γ-Al₂O₃-NPs (flake versus rod) and their effects on metabolic profiles of astrocytes in rat cerebral cortex. While exposed to both shapes caused significant cytotoxicity and apoptosis in a dose-dependent manner after 72 h exposure, a significantly stronger response was observed for nanorods than for nanoflakes. These effects were associated with significantly greater ROS accumulation and inflammation induction, as indicated by increased concentrations of IL-1β, IL-2 and IL-6. Using untargeted metabolomics, significant alternations in metabolism of amino acids, lipids and purines, and pyrimidines were observed after exposure to both types. Moreover, changes in the metabolome caused by nanorods were significantly greater than those by nanoflakes as also indicated by physiological stress responses to ROS, inflammation, and apoptosis. Taken together, these findings demonstrated the critical role of morphology in determining toxic potencies of nano-alumina and its underlying mechanisms of toxic actions.

Taurine-mediated browning of white adipose tissue is involved in its anti-obesity effect in mice

Taurine, a nonprotein amino acid, is widely distributed in almost all animal tissues. Ingestion of taurine helps to improve obesity and its related metabolic disorders. However, the molecular mechanism underlying the protective role of taurine against obesity is not completely understood. In this study, it was found that intraperitoneal treatment of mice with taurine alleviated high-fat diet (HFD)-induced obesity, improved insulin sensitivity, and increased energy expenditure and adaptive thermogenesis of the mice. Meanwhile, administration of the mice with taurine markedly induced the browning of inguinal white adipose tissue (iWAT) with significantly elevated expression of PGC1α, UCP1, and other thermogenic genes in iWAT. In vitro studies indicated that taurine also induced the development of brown-like adipocytes in C3H10T1/2 white adipocytes. Knockdown of PGC1α blunted the role of taurine in promoting the brown-like adipocyte phenotypes in C3H10T1/2 cells. Moreover, taurine treatment enhanced AMPK phosphorylation in vitro and in vivo, and knockdown of AMPKα1 prevented taurine-mediated induction of PGC1α in C3H10T1/2 cells. Consistently, specific knockdown of PGC1α in iWAT of the HFD-fed mice inhibited taurine-induced browning of iWAT, with the role of taurine in the enhancement of adaptive thermogenesis, the prevention of obesity, and the improvement of insulin sensitivity being partially impaired. These results reveal a functional role of taurine in facilitating the browning of white adipose tissue, which depends on the induction of PGC1α. Our studies also suggest a potential mechanism for the protective role of taurine against obesity, which involves taurine-mediated browning of white adipose tissue.

Novel Markers of the Metabolic Impact of Exogenous Retinoic Acid with A Focus on Acylcarnitines and Amino Acids

Treatment with all-trans retinoic acid (ATRA), the carboxylic form of vitamin A, lowers body weight in rodents by promoting oxidative metabolism in multiple tissues including white and brown adipose tissues. We aimed to identify novel markers of the metabolic impact of ATRA through targeted blood metabolomics analyses, with a focus on acylcarnitines and amino acids. Blood was obtained from mice treated with a high ATRA dose (50 mg/kg body weight/day, subcutaneous injection) or placebo (controls) during the 4 days preceding collection. LC-MS/MS analyses with a focus on acylcarnitines and amino acids were conducted on plasma and PBMC. Main results showed that, relative to controls, ATRA-treated mice had in plasma: increased levels of carnitine, acetylcarnitine, and longer acylcarnitine species; decreased levels of citrulline, and increased global arginine bioavailability ratio for nitric oxide synthesis; increased levels of creatine, taurine and docosahexaenoic acid; and a decreased n-6/n-3 polyunsaturated fatty acids ratio. While some of these features likely reflect the stimulation of lipid mobilization and oxidation promoted by ATRA treatment systemically, other may also play a causal role underlying ATRA actions. The results connect ATRA to specific nutrition-modulated biochemical pathways, and suggest novel mechanisms of action of vitamin A-derived retinoic acid on metabolic health.

Taurine supplementation increases irisin levels after high intensity physical training in obese women

BACKGROUND

Irisin is a myokine/adipokine that under stimulus of physical exercise is able to improve thermogenic capacity in adipose tissue. Likewise, taurine supplementation has demonstrated similar effects on energy metabolism. Therefore, we hypothesized that taurine supplementation combined with physical training may induce an increase in irisin concentrations, optimizing energy metabolism in obese individuals.

OBJECTIVE

To evaluate if taurine supplementation associated with a high intensity physical training program increases irisin levels in obese women.

METHODS

double-blind study with 22 obese women (BMI 32.4 ± 2.0 kg/m², 36.6 ± 6.4 years and sedentary) who were randomly divided into two groups, control group (GC, n = 14), exercised and supplemented with placebo (3 g of starch), and taurine group (GTAU, n = 8), exercised and supplemented with taurine (3 g). The subjects performed high intensity physical training, Deep Water Running (DWR), for 8 weeks, 3 times/week, for 50 min per training session, at 70-85% maximum heart rate. Resting metabolic rate (RMR) was evaluated by indirect calorimetry, body composition by deuterium oxide, plasma taurine by HPLC, plasma irisin by Multiplex Kit, and food consumption by food records. The results were analyzed by an ANOVA two way repeated measures mixed model, with the Sidak post hoc (p < 0.05).

RESULTS

No changes were observed in body composition. DWR increased RMR independent of supplementation (p < 0.001) and irisin levels (pg/mL) showed a significant difference only in the GTAU in 1 h after exercise (p < 0.001).

CONCLUSION

DWR associated with taurine supplementation resulted in increased plasma irisin concentrations after physical training in obese adult women.

Metabolomics Profiling before, during, and after the Beijing Olympics: A Panel Study of Within-Individual Differences during Periods of High and Low Air Pollution

BACKGROUND

The metabolome is a collection of exogenous chemicals and metabolites from cellular processes that may reflect the body's response to environmental exposures. Studies of air pollution and metabolomics are limited.

OBJECTIVES

To explore changes in the human metabolome before, during, and after the 2008 Beijing Olympics Games, when air pollution was high, low, and high, respectively.

METHODS

Serum samples were collected before, during, and after the Olympics from 26 participants in an existing panel study. Gas and ultra-high performance liquid chromatography/mass spectrometry were used in metabolomics analysis. Repeated measures ANOVA, network analysis, and enrichment analysis methods were employed to identify metabolites and classes associated with air pollution changes.

RESULTS

A total of 886 molecules were measured in our metabolomics analysis. Network partitioning identified four modules with 65 known metabolites that significantly changed across the three time points. All known molecules in the first module ([Formula: see text]) were lipids (e.g., eicosapentaenoic acid, stearic acid). The second module consisted primarily of dipeptides ([Formula: see text], e.g., isoleucylglycine) plus 8 metabolites from four other classes (e.g., hypoxanthine, 12-hydroxyeicosatetraenoic acid). Most of the metabolites in Modules 3 (19 of 23) and 4 (5 of 5) were unknown. Enrichment analysis of module-identified metabolites indicted significantly overrepresented pathways, including long- and medium-chain fatty acids, polyunsaturated fatty acids (n3 and n6), eicosanoids, lysolipid, dipeptides, fatty acid metabolism, and purine metabolism [(hypo) xanthine/inosine-containing pathways].

CONCLUSIONS

We identified two major metabolic signatures: one consisting of lipids, and a second that included dipeptides, polyunsaturated fatty acids, taurine, and xanthine. Metabolites in both groups decreased during the 2008 Beijing Olympics, when air pollution was low, and increased after the Olympics, when air pollution returned to normal (high) levels. https://doi.org/10.1289/EHP3705.

A preclinical study to model taurine pharmokinetics in the undernourished rat

Malnutrition is a common feature of chronic and acute diseases, often associated with a poor prognosis, including worsening of clinical outcome, owing, among other factors, to dysfunction of the most internal organs and systems affecting the absorption, metabolism and elimination of drugs and nutrients. Taurine is involved in numerous biological processes and is required in increased amounts in response to pathological conditions. The aim of this study was to describe the behaviour of taurine in well-nourished (WN) rats and to analyse the influence of protein-energy undernutrition on the pharmacokinetic (PK) parameters of taurine, using a PK model. Wistar rats were randomly distributed into two groups, WN and undernourished (UN), and taurine was administered intravenously or orally at different doses: 1, 10 and 100 mg. Population pharmacokinetic modelling of plasma levels was performed using the NONMEM 7.2 program. Several distribution and absorption models were explored in combination with dose and/or time covariate effects. Covariates such as nutritional status, serum albumin, body weight and score of undernutrition were used. A two-compartment population pharmacokinetic model with zero-order endogenous formation, passive absorption, first-order kinetics distribution and non-linear elimination with parallel Michaelis-Menten excretion and reabsorption processes best described taurine pharmacokinetics. Undernutrition acted as a covariate reducing the V max of the active elimination process. Data analysis showed linear absorption and distribution, and non-linear elimination processes for taurine. Elimination of taurine was reduced in UN animals, suggesting that the reabsorption process via the secretion transporter was modified in that group.

The Relationship between Plasma Taurine Levels and Diabetic Complications in Patients with Type 2 Diabetes Mellitus

Background: Taurine has an active role in providing glucose homeostasis and diabetes causes a decline in taurine levels. This paper investigates the relationship between taurine and diabetic complications, patients' demographic features, and biochemical parameters. Methods: Fifty-nine patients with type 2 diabetes mellitus (T2DM), and 28 healthy control subjects between the ages of 32 and 82 were included in the study. The mean age of subjects was 55.6 ± 10.3 and mean diabetes duration was 10.2 ± 6.0 years. The most commonly accompanying comorbidity was hypertension (HT) (64.5%, n = 38), and the most frequent diabetic complication was neuropathy (50.8%, n = 30). Plasma taurine concentrations were measured by an enzyme-linked immunoassay (ELISA) kit. Results: Plasma taurine concentrations were significantly lower in diabetic patients (0.6 ± 0.1 mmol/L) than controls (0.8 ± 0.2 mmol/L) and in hypertensive (0. 6 ± 0.1 mmol/L) patients (p = 0.000, p = 0.027 respectively). Conclusion: Plasma taurine levels were decreased in patients with T2DM and this was not related to FBG, HbA1c, and microalbuminuria. With regard to complications, we only found a correlation with neuropathy. We suggest that taurine levels may be more important in the development of diabetes; however, it may also have importance for the progression of the disease and the subsequent complications. We further assert that taurine measurement at different times may highlight whether there is a causal relationship in the development of complications.

The Protection of Taurine on Abnormal Expression of Deiodinase 3 Induced by BDE 209 in JEG Cells Under the Normal Culture Conditions

Taurine is an important amino acid for the growth and development of the central nervous system and plays an important role in the development of the nervous system. Many studies have shown that taurine can prevent and repair neurodevelopmental damage, and its mechanism has also become a research hotspot. While most studies focus on nerve cells, less on placental cells that are closely related to early neurodevelopment (developmental neurotoxicity) by modulating fetal circulation level of thyroid hormones. Studies have shown that exposure of placental cells to the common environmental endocrine disruptor BDE 209 during early pregnancy may lead to developmental neurotoxicity due to thyroid hormone interference caused by abnormal expression of deiodinases. Therefore, in this study, the placenta-derived JEG cells cultured at 95% air/5% CO2 was used as a in vitro model, and the potential protection from taurine on BDE 209-mediated cytotoxicity was examined. When BDE 209 was found to cause a decrease in cell viability and disturbance in the gene and protein expressions of placental deiodinase 3, pretreatment of the JEG cells with taurine can moderately reduce the BDE 209-meditated cytotoxicity, and restore gene and protein expressions of placental deiodinase, so that thyroid hormone levels tend to be normal in cell culture medium. Our data suggest that taurine may have some protection on the developmental neurotoxicity caused by BDE 209.

Roux-en-Y gastric bypass surgery alters serum metabolites and fatty acids in patients with morbid obesity

AIM

Bariatric surgery induces significant weight loss, increases insulin sensitivity, and reduces mortality, but the underlying mechanisms are not clear. It was hypothesized that Roux-en-Y gastric bypass (RYGB) surgery improves metabolic profile along with weight loss. The objective of this pilot study was to evaluate changes in serum metabolites and fatty acids (FA) at 2 weeks and 6 months after RYGB.

MATERIALS AND METHODS

Serum samples were collected pre-surgery, at 2 weeks and 6 months post-surgery from 20 patients undergoing RYGB surgery. Serum non-esterified free FA (NEFA) were measured. Serum metabolites and FA were measured using nuclear magnetic resonance spectroscopy and improved direct fatty acid methyl ester synthesis and the gas chromatography/mass spectrometry method, respectively, in subjects who completed follow-up at 6 months (n = 8).

RESULTS

Mean (standard deviation) percent total weight loss was 6.70% (1.7) and 24.91% (6.63) at 2 weeks (n = 15) and 6 months (n = 8) post-surgery, respectively. NEFA were significantly reduced at 6 months post-surgery (P = 0.001, n = 8). Serum branched chain amino acids, 2-aminobutyrate, butyrate, 2-hydroxybutyrate, 3-hydroxybutyrate, acetone, 2-methylglutarate, and 2-oxoisocaproate were significantly reduced, while serum alanine, glycine, pyruvate, and taurine were significantly elevated at 6 months post-surgery compared with pre-surgery (n = 8, P < 0.05). Also, serum FA C10:0, C13:0, C14:0, C15:0, and C18:0 increased significantly (n = 8, P < 0.05) by 6 months post-surgery.

CONCLUSIONS

Changes in serum metabolites and FA at 6 months post-RYGB surgery in this pilot study with limited number of participants are suggestive of metabolic improvement; larger studies are warranted for confirmation.

Perinatal Taurine Supplementation Prevents Metabolic and Cardiovascular Effects of Maternal Diabetes in Adult Rat Offspring

This study tests the hypothesis that perinatal taurine supplementation prevents diabetes mellitus and hypertension in adult offspring of maternal diabetic rats. Female Wistar rats were fed normal rat chow and tap water with (Diabetes group) or without diabetic induction by intraperitoneal streptozotocin injection (Control group) before pregnancy. Then, they were supplemented with 3% taurine in water (Control+T and Diabetes+T groups) or water alone from conception to weaning. After weaning, both male and female offspring were fed normal rat chow and tap water throughout the study. Blood chemistry and cardiovascular parameters were studied in 16-week old rats. Body, heart, and kidney weights were not significantly different among the eight groups. Further, lipid profiles except triglyceride were not significantly different among male and female groups, while male Diabetes displayed increased fasting blood glucose, decreased plasma insulin, and increased plasma triglyceride compared to other groups. Compared to Control, mean arterial pressures significantly increased and baroreflex control of heart rate decreased in both male and female Diabetes, while heart rates significantly decreased in male but increased in female Diabetes group. Although perinatal taurine supplementation did not affect any measured parameters in Control groups, it abolished the adverse effects of maternal diabetes on fasting blood glucose, plasma insulin, lipid profiles, mean arterial pressure, heart rate, and baroreflex sensitivity in adult male and female offspring. The present study indicates that maternal diabetes mellitus induces metabolic and cardiovascular defects more in male than female adult offspring, and these adverse effects can be prevented by perinatal taurine supplementation.

Comparison of Toxicity of Taurine and GABA in Combination with Alcohol in 7-Day-Old Mice

Previously, we described the combined toxicity of taurine and alcohol, and assumed hypoglycemia to be one reason of this toxicity. To understand whether taurine-ethanol combined toxicity is exclusively connected to taurine or whether other inhibitory amino acids may have similar effects when combined with ethanol, we tested different doses of gamma-aminobutyric acid (GABA) in combination with ethanol in 7-day-old mice. The minimal dose of GABA in combination with 5 g/kg ethanol which could kill a mouse was 2 g/kg. GABA combined with ethanol at doses of 3 g/kg, 4 g/kg, 6 g/kg induced lethality of 30%, 90% and 100%, correspondingly. Taurine at the doses of 4 and 6 g/kg combined with ethanol induced death in 60 and 100% of mice. Ethanol (5 g/kg), taurine (6 g/kg), GABA (4 g/kg) administered alone and the combination of ethanol (5 g/kg) with taurine (3 g/kg) have no lethal effects. GABA (6 g/kg) applied alone induced 90% lethality. Taurine or GABA alone decreased blood glucose in a dose-depending manner. Ethanol potentiated GABA- and taurine-induced decrease in blood glucose and in some animals it dropped from 8.8 (intact) to a hypoglycemic level 3.1-3.3 mmol/L (GABA 4 g/kg, taurine 6 g/kg), but this may not be considered a single reason of death. We conclude that the combination of GABA and ethanol has a lethal effect and this is stronger than the combined toxicity of ethanol and taurine.

Construction of a high-density genetic map and fine QTL mapping for growth and nutritional traits of Crassostrea gigas

BACKGROUND

Both growth and nutritional traits are important economic traits of Crassostrea gigas (C. gigas) in industry. But few work has been done to study the genetic architecture of nutritional traits of the oyster. In this study, we constructed a high-density genetic map of C. gigas to help assemble the genome sequence onto chromosomes, meanwhile explore the genetic basis for nutritional traits via quantitative trait loci (QTL) mapping.

RESULTS

The constructed genetic map contained 5024 evenly distributed markers, with an average marker interval of 0.68 cM, thus representing the densest genetic map produced for the oyster. According to the high collinearity between the consensus map and the oyster genome, 1574 scaffold (about 70%) of the genome sequence of C. gigas were successfully anchored to 10 linkage groups (LGs) of the consensus map. Using this high-qualified genetic map, we then conducted QTL analysis for growth and nutritional traits, the latter of which includes glycogen, amino acid (AA), and fatty acid (FA). Overall, 41 QTLs were detected for 17 traits. In addition, six candidate genes identified in the QTL interval showed significant correlation with the traits on transcriptional levels. These genes include growth-related genes AMY and BMP1, AA metabolism related genes PLSCR and GR, and FA metabolism regulation genes DYRK and ADAMTS.

CONCLUSION

Using the constructed high-qualified linkage map, this study not only assembled nearly 70% of the oyster genome sequence onto chromosomes, but also identified valuable markers and candidate genes for growth and nutritional traits, especially for AA and FA that undergone few studies before. These findings will facilitate genome assembly and molecular breeding of important economic traits in C. gigas.

Effects and Mechanisms of Taurine as a Therapeutic Agent

Taurine is an abundant, β-amino acid with diverse cytoprotective activity. In some species, taurine is an essential nutrient but in man it is considered a semi-essential nutrient, although cells lacking taurine show major pathology. These findings have spurred interest in the potential use of taurine as a therapeutic agent. The discovery that taurine is an effective therapy against congestive heart failure led to the study of taurine as a therapeutic agent against other disease conditions. Today, taurine has been approved for the treatment of congestive heart failure in Japan and shows promise in the treatment of several other diseases. The present review summarizes studies supporting a role of taurine in the treatment of diseases of muscle, the central nervous system, and the cardiovascular system. In addition, taurine is extremely effective in the treatment of the mitochondrial disease, mitochondrial encephalopathy, lactic acidosis, and stroke-like episodes (MELAS), and offers a new approach for the treatment of metabolic diseases, such as diabetes, and inflammatory diseases, such as arthritis. The review also addresses the functions of taurine (regulation of antioxidation, energy metabolism, gene expression, ER stress, neuromodulation, quality control and calcium homeostasis) underlying these therapeutic actions.

Acute intraperitoneal administration of taurine decreases the glycemia and reduces food intake in type 1 diabetic rats

Taurine, an amino acid with antioxidant and osmoregulatory properties, has been studied for its possible antidiabetic properties in type 1 and type 2 diabetic animals. In type 2 diabetic mice, taurine decreases blood glucose through increased insulin secretion and insulin receptor sensitization. However, insulin is absent in type 1 diabetic individuals. The aim of this study was to evaluate the effects of taurine on parameters related to the energy balance that could explain the metabolic action of this amino acid in type 1 diabetic rats. Control and streptozotocin-induced diabetic rats received saline or taurine (100 mg/kg/day), intraperitoneally, for 30 days. Parameters such as palatable food intake, gastrointestinal transit rate, serum glucose, insulin, leptin, and glucagon levels were measured 60 min after the last taurine administration. Liver, kidneys, heart, and retroperitoneal fat were dissected and weighted. Glycogen levels were measured in the liver and soleus muscle. Our results showed that acute taurine administration decreased glycemia. It also decreased food intake in diabetic rats, without affecting other metabolic parameters. Altogether, our results suggest that in type 1 diabetic rats, taurine decreases blood glucose by a non-insulin-dependent mechanism. Due to the safety profile of taurine, and its effect on glycemia, this amino acid may help to design new drugs to add benefit to insulin therapy in type 1 diabetic individuals.

Toxicity assessment of hydrogen peroxide on Toll-like receptor system, apoptosis, and mitochondrial respiration in piglets and IPEC-J2 cells

In this study, expressions of toll-like receptors (TLRs) and apoptosis-related genes in piglets and mitochondrial respiration in intestinal porcine epithelial cells were investigated after hydrogen peroxide (H₂O₂) exposure. The in vivo results showed that H₂O₂ influenced intestinal expressions of TLRs and apoptosis related genes. H₂O₂ treatment (5% and 10%) downregulated uncoupling protein 2 (UCP2) expression in the duodenum (P < 0.05), while low dosage of H2O2 significantly increased UCP2 expression in the jejunum (P < 0.05). In IPEC-J2 cells, H₂O₂ inhibited cell proliferation (P < 0.05) and caused mitochondrial dysfunction via reducing maximal respiration, spare respiratory, non-mitochondrial respiratory, and ATP production (P < 0.05). However, 50 uM H₂O₂ significantly enhanced mitochondrial proton leak (P < 0.05). In conclusion, H₂O₂ affected intestinal TLRs system, apoptosis related genes, and mitochondrial dysfunction in vivo and in vitro models. Meanwhile, low dosage of H₂O₂ might exhibit a feedback regulatory mechanism against oxidative injury via increasing UCP2 expression and mitochondrial proton leak.

The Emerging Role of Vitamin B6 in Inflammation and Carcinogenesis

Vitamin B6 serves as a coenzyme catalyzing more than 150 enzymes regulating metabolism and synthesis of proteins, carbohydrates, lipids, heme, and important bioactive metabolites. For several years vitamin B6 and its vitamers (B6) were recognized as antioxidant and antiinflammatory and in modulating immunity and gene expression. During the last 10 years, there were growing reports implicating B6 in inflammation and inflammation-related chronic illnesses including cancer. It is unclear if the deficiency of B6 or additional intake of B6, above the current requirement, should be the focus. Whether the current recommended daily intake for B6 is adequate should be revisited, since B6 is important to human health beyond its role as a coenzyme and its status is affected by many factors including but not limited to age, obesity, and inflammation associated with chronic illnesses. A link between inflammation B6 status and carcinogenesis is not yet completely understood. B6-mediated synthesis of H₂S, a gasotransmitter, and taurine in health and disease, especially in maintaining mitochondrial integrity and biogenesis and inflammation, remains an important area to be explored. Recent developments in the molecular role of B6 and its direct interaction with inflammasomes, and nuclear receptor corepressor and coactivator, receptor-interacting protein 140, provide a strong impetus to further explore the multifaceted role of B6 in carcinogenesis and human health.

Antiobesity Efficacy of Quercetin-Rich Supplement on Diet-Induced Obese Rats: Effects on Body Composition, Serum Lipid Profile, and Gene Expression

The antiobesity effects of quercetin-rich supplement (QRS), which contain quercetin, lycopene, taurine, and litchi flower extract, on a high-fat diet (HFD)-induced obese rats were investigated. The rats that consume HFD with QRS (185 mg/kg rat) have significantly modulated the final body weights [490 ± 11 (HFD) → 441 ± 11 (HFD+QRS) g], total body fat [112.9 ± 4.5 (HFD) → 86.6 ± 5.7 (HFD+QRS) g], liver weights [14.8 ± 0.4 (HFD) → 12.6 ± 0.4 (HFD+QRS) g/rat], and the serum TG [102.5 ± 7.3 (HFD) → 90.7 ± 6.5 (HFD+QRS) mg/dL] to a level that resembled the regular diet-consumed rats (p < 0.05). The excretion of lipid in the faeces augmented in QRS groups as compared with the nonsupplemented HFD group [faecal total lipid: 62.43 ± 2.80 (HFD) → 73.15 ± 0.88 (HFD+QRS) mg/g dried faeces, p < 0.05]. In the histological analysis, quercetin-rich formulation supplemented groups presented a much less lipid accumulation and smaller size of adipocytes. Moreover, a decreased serum thiobarbituric acid reactive substances [1.55 ± 0.17 (HFD) → 0.78 ± 0.04 (HFD+QRS) nmol MDA eq/mL serum] increased levels of serum Trolox equivalent antioxidant capacity [3.89 ± 0.08 (HFD) → 6.46 ± 0.20 (HFD+QRS) μmol/mL serum], and more active hepatic antioxidant enzymes were observed in the supplemented groups (p < 0.05). The result of this work is a good demonstration of how a combination of bioactive compounds could work synergistically and become very effective in disease prevention.

[Doping with illegal and legal substances in old age]

The number of old persons who participate in sports and can even achieve peak performances is increasing steadily. Normal aging, however, is associated with decreased muscle strength and a decline in cardiovascular endurance even in those persons who regularly participate in sports. Thus, it seems obvious to impact on muscle mass and muscle strength by using anabolic substances. The number of older persons who illegally use doping substances is currently unknown. Besides classical anabolic drugs, other proteins and amino acids are used to impact on muscle mass or strength. This article provides some insights into clinical trials of classical anabolic drugs in older persons and gives an overview on more recent studies examining the potential effects of taurine, creatine and whey protein in older persons.

Taurine as a water structure breaker and protein stabilizer

The enhancing effect on the water structure has been confirmed for most of the osmolytes exhibiting both stabilizing and destabilizing properties in regard to proteins. The presented work concerns osmolytes, which should be classified as "structure breaking" solutes: taurine and N,N,N-trimethyltaurine (TMT). Here, we combine FTIR spectroscopy, DSC calorimetry and DFT calculations to gain an insight into the interactions between osmolytes and two proteins: lysozyme and ubiquitin. Despite high structural similarity, both osmolytes exert different influence on protein stability: taurine is a stabilizer, TMT is a denaturant. We show also that taurine amino group interacts directly with the side chains of proteins, whereas TMT does not interact with proteins at all. Although two solutes weaken on average the structure of the surrounding water, their hydration spheres are different. Taurine is surrounded by two populations of water molecules: bonded with weak H-bonds around sulfonate group, and strongly bonded around amino group. The strong hydrogen-bonded network of water molecules around the amino group of taurine further improves properties of enhanced protein hydration sphere and stabilizes the native protein form. Direct interactions of this group with surface side chains provide a proper orientation of taurine and prevents the [Formula: see text] group from negative influence. The weakened [Formula: see text] hydration sphere of TMT breaks up the hydrogen-bonded network of water around the protein and destabilizes it. However, TMT at low concentration stabilize both proteins to a small extent. This effect can be attributed to an actual osmophobic effect which is overcome if the concentration increases.

Preliminary metabolomics analysis of placenta in maternal obesity

INTRODUCTION

Metabolomics identifies phenotypical groups with specific metabolic profiles, being increasingly applied to several pregnancy conditions. This is the first preliminary study analyzing placental metabolomics in normal weight (NW) and obese (OB) pregnancies.

METHODS

Twenty NW (18.5 ≤ BMI< 25 kg/m²) and eighteen OB (BMI≥ 30 kg/m²) pregnancies were studied. Placental biopsies were collected at elective caesarean section. Metabolites extraction method was optimized for hydrophilic and lipophilic phases, then analyzed with GC-MS. Univariate and PLS-DA multivariate analysis were applied.

RESULTS

Univariate analysis showed increased uracil levels while multivariate PLS-DA analysis revealed lower levels of LC-PUFA derivatives in the lipophilic phase and several metabolites with significantly different levels in the hydrophilic phase of OB vs NW.

DISCUSSION

Placental metabolome analysis of obese pregnancies showed differences in metabolites involved in antioxidant defenses, nucleotide production, as well as lipid synthesis and energy production, supporting a shift towards higher placental metabolism. OB placentas also showed a specific fatty acids profile suggesting a disruption of LC-PUFA biomagnification. This study can lay the foundation to further metabolomic placental characterization in maternal obesity. Metabolic signatures in obese placentas may reflect changes occurring in the intrauterine metabolic environment, which may affect the development of adult diseases.

Taurine supplementation can increase lipolysis and affect the contribution of energy systems during front crawl maximal effort

Taurine can affect the energy system metabolism, specifically the lipid metabolism, since an increase in lipid oxidation may promote carbohydrate savings. We hypothesized that taurine supplementation associated with high-intensity exercise could increase levels of lipolysis, benefiting swimmer performance. Nine male competitive swimmers performed two 400-m front crawl maximal efforts with a 1-week washout, and the athletes received 6 g of taurine (TAU) or placebo (PLA) supplementation 120 min before performing the effort. Oxygen consumption and the contribution of the energy systems were analyzed post effort using a Quark CPET gas analyzer. Blood samples were collected before, and 5 min post the effort for taurine and glycerol analysis. Immediately before and 3, 5, and 7 min post the effort, blood samples from the earlobe were collected to determine lactate levels. An increase of 159% was observed in taurine plasma levels 120 min post ingestion. Glycerol levels were higher in both groups post effort; however, the TAU condition promoted an 8% higher increase than the PLA. No changes were observed in swimmer performance or lactate levels; however, the percentage change in lactate levels (∆[La^-]) was different (TAU: 9.36 ± 2.78 mmol L^-1; PLA: 11.52 ± 2.19 mmol L^-1, p = 0.04). Acute taurine supplementation 120 min before performing a maximal effort did not improve swimmer performance; however, it increased glycerol plasma levels and reduced both the ∆[La^-] and lactic anaerobic system contribution.

Taurine: A Potential Ergogenic Aid for Preventing Muscle Damage and Protein Catabolism and Decreasing Oxidative Stress Produced by Endurance Exercise

The aim of this study was to evaluate the effects of taurine and chocolate milk supplementation on oxidative stress and protein metabolism markers, and aerobic parameters in triathletes.

Methods: A double-blind, crossover study was conducted with 10 male triathletes, aged 30.9 ± 1.3 year, height 1.79 ± 0.01 m and body weight 77.45 ± 2.4 kg. Three grams of taurine and 400 ml of chocolate milk (TAUchoc), or a placebo (chocolate milk) (CHOC) was ingested post exercise for 8 weeks. Oxidative stress marker levels, and 24 h urinary nitrogen, creatinine, and urea excretion were measured before and after 8 weeks of training and supplementation with TAUchoc or CHOC. A maximal incremental running test on a treadmill was performed in order to evaluate aerobic parameters: V_max, heart rate (HR) and rate of perceived exertion (RPE).

Results: TAUchoc treatment during the 8 weeks resulted in increased taurine plasma levels (PRE 201.32 ± 29.03 μmol/L and POST 234.36 ± 35.51 μmol/L, p = 0.01), decreased malondialdehyde levels (19.4%, p = 0.03) and urinary nitrogen excretion (−33%, p = 0.03), and promoted positive nitrogen balance (p = 0.01). There were no changes in reduced glutathione (TAUchoc PRE 0.72 ± 0.08 mmol/L and POST 0.83 ± 0.08 mmol/L; CHOC PRE 0.69 ± 0.08 mmol/L and POST 0.81 ± 0.06 mmol/L), vitamin E plasma levels (TAUchoc PRE 33.99 ± 2.52 μmol/L and 35.95 ± 2.80 μmol/L and CHOC PRE 31.48 ± 2.12 μmol/L and POST 33.77 ± 3.64 μmol/L), or aerobic parameters, which were obtained in the last phase of the maximal incremental running test (V_max TAUchoc PRE 13 ± 1.4 km/h and POST 13.22 ± 1.34 km/h; CHOC PRE 13.11 ± 2.34 km/h and POST 13.11 ± 2.72 km/h), the heart rate values were TAUchoc PRE 181.89 ± 24.18 bpm and POST 168.89 ± 46.56 bpm; CHOC PRE 181.56 ± 2.14 bpm and POST 179.78 ± 3.4 bpm, and the RPE were TAUchoc PRE 8.33 ± 2.4 AU and POST 9.1 ± 2.1 AU; CHOC PRE 8.11 ± 4.94 AU and POST 8.78 ± 2.78 AU).

Conclusion: Taurine supplementation did not improve aerobic parameters, but was effective in increasing taurine plasma levels and decreasing oxidative stress markers, which suggests that taurine may prevent oxidative stress in triathletes.

The urine metabolome differs between lean and overweight Labrador Retriever dogs during a feed-challenge

Obesity in dogs is an increasing problem and better knowledge of the metabolism of overweight dogs is needed. Identification of molecular changes related to overweight may lead to new methods to improve obesity prevention and treatment. The aim of the study was firstly to investigate whether Nuclear Magnetic Resonance (NMR) based metabolomics could be used to differentiate postprandial from fasting urine in dogs, and secondly to investigate whether metabolite profiles differ between lean and overweight dogs in fasting and postprandial urine, respectively. Twenty-eight healthy intact male Labrador Retrievers were included, 12 of which were classified as lean (body condition score (BCS) 4-5 on a 9-point scale) and 16 as overweight (BCS 6-8). After overnight fasting, a voided morning urine sample was collected. Dogs were then fed a high-fat mixed meal and postprandial urine was collected after 3 hours. Metabolic profiles were generated using NMR and 45 metabolites identified from the spectral data were evaluated using multivariate data analysis. The results revealed that fasting and postprandial urine differed in relative metabolite concentration (partial least-squares discriminant analysis (PLS-DA) 1 comp: R2Y = 0.4, Q2Y = 0.32; cross-validated ANOVA: P = 0.00006). Univariate analyses of discriminant metabolites showed that taurine and citrate concentrations were elevated in postprandial urine, while allantoin concentration had decreased. Interestingly, lean and overweight dogs differed in terms of relative metabolite concentrations in postprandial urine (PLS-DA 1 comp: R2Y = 0.5, Q2Y = 0.36, cross-validated ANOVA: P = 0.005) but not in fasting urine. Overweight dogs had lower postprandial taurine and a trend of higher allantoin concentrations compared with lean dogs. These findings demonstrate that metabolomics can differentiate 3-hour postprandial urine from fasting urine in dogs, and that postprandial urine metabolites may be more useful than fasting metabolites for identification of metabolic alterations linked to overweight. The lowered urinary taurine concentration in overweight dogs could indicate alterations in lipid metabolism and merits further investigation.

Plasma Taurine, Diabetes Genetic Predisposition, and Changes of Insulin Sensitivity in Response to Weight-Loss Diets

CONTEXT

Taurine metabolism disturbance is closely linked to obesity, insulin resistance, and diabetes. Previous evidence suggested that the preventative effects of taurine on diabetes might be through regulating the expression levels of diabetes-related genes.

OBJECTIVE

We estimated whether blood taurine levels modified the overall genetic susceptibility to diabetes on improvement of insulin sensitivity in a randomized dietary trial.

DESIGN AND SETTING

We genotyped 31 diabetes-associated variants to calculate a genetic risk score (GRS) and measured plasma taurine levels and glycemic traits among participants from the Preventing Overweight Using Novel Dietary Strategies (POUNDS Lost) trial.

PARTICIPANTS

Seven-hundred eleven overweight or obese participants (age 30-70 y; 60% females) had genetic variants genotyped and blood taurine levels measured.

INTERVENTION

Participants went on 2-year weight-loss diets, which were different in macronutrient composition.

MAIN OUTCOME MEASURE

Improvements in glycemic traits were measured.

RESULTS

We found that baseline taurine levels significantly modified the effects of diabetes GRS on changes in fasting glucose, insulin, and homeostatic model assessment of insulin resistance (HOMA-IR) during the 2-year diet intervention (P-interaction = .04, .01, .002, respectively), regardless of weight loss. High baseline taurine levels were associated with a less reduction in both glucose and HOMA-IR among the participants with the lowest tertile of diabetes GRS (both P = .02), and with a greater reduction in both insulin and HOMA-IR among those with the highest tertile of diabetes GRS (both P = .04).

CONCLUSIONS

Our data suggest that blood taurine levels might differentially modulate the effects of diabetes-related genes on improvement of insulin sensitivity among overweight/obese patients on weight-loss diets.