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Metabolic switching has been raised as an important phenomenon to be studied in relation to xenobiotic metabolites, since the dose of the exposure determines the formation of metabolites and their bioactivity. Limonene is a monoterpene mostly found in citrus fruits with health activity, and its phase II metabolites and activity are still not clear. The aim of this work was to evaluate the effects of D-limonene in the development of diet-induced obesity in mice and to investigate metabolites that could be generated in a study assessing different doses of supplementation. Animals were induced to obesity and supplemented with 0.1% or 0.8% D-limonene added to the feed. Limonene phase I and II metabolites were identified in liver and urine by LC-ESI-qToF-MS/MS. To the best of our knowledge, in this study three new phase I metabolites and ten different phase II metabolites were first attributed to D-limonene. Supplementation with 0.1% D-limonene was associated with lower weight gain and a trend to lower accumulation of adipose tissue deposits. The metabolites limonene-8,9-diol, perillic acid and perillic acid-8,9-diol should be explored in future research as anti-obesogenic agents as they were the metabolites most abundant in the urine of mice that received 0.1% D-limonene in their feed.

The modulation of energy expenditure by dietary administration of cholic acid in mice promoted interest in studying bile acid(s) (BA) as adjuvants in the treatment of metabolic diseases such as obesity and diabetes. Bile acids can modulate intermediary metabolism by acting directly on nuclear as well as G-protein-coupled receptors or indirectly through changes in gut microbiota. Despite the potential of BA to affect intermediary metabolism, plasma kinetics and changes in individual BA in blood in the post-prandial state have been neglected for a long time. Minutes after ingestion of a meal (or a glucose challenge), the plasma BA concentration increases as a result of the secretion of bile into the duodenum, followed by intestinal absorption and a systemic circulation spillover. A large inter-individual variability of post-prandial kinetics of plasma BA is documented. Factors such as gender, diet composition, circadian oscillations, and individual capacities for the synthesis and transport of BA play important roles in determining this variability and are discussed in the present short review in light of new findings.

Background/aims Skeletal mass loss is reported in several catabolic conditions and it has been associated with a reduced intracellular L-glutamine content. We investigated the association of intracellular L-glutamine concentration with the protein content in skeletal muscle cells. Methods We cultivated C2C12 myotubes in the absence or presence of 2 (reference condition), 8 or 16 mM L-glutamine for 48 hours, and the variations in the contents of amino acids and proteins measured. We used an inhibitor of L-glutamine synthesis (L-methionine sulfoximine - MSO) to promote a further reduction in intracellular L-glutamine levels. Amino acids contents in cells and media were measured using LC-MS/MS. We measured changes in phosphorylated Akt, RP-S6, and 4E-BP1contents in the absence or presence of insulin by western blotting. Results Reduced intracellular L-glutamine concentration was associated with decreased protein content and increased protein breakdown. Low intracellular glutamine levels were also associated with decreased p-Akt contents in the presence of insulin. A further decrease in intracellular L-glutamine caused by glutamine synthetase inhibitor reduced protein content and levels of amino acids generated from glutamine metabolism and increased bAib still further. Cells exposed to high medium glutamine levels did not have any change in protein content but exhibited increased contents of the amino acids derived from L-glutamine metabolism. Conclusion Intracellular L-glutamine levels per se play a role in the control of protein content in skeletal muscle myotubes.

Roux-en-Y gastric bypass (RYGB) is an effective method to achieve sustained weight loss, but the mechanisms responsible for RYGB effects have not yet been fully characterized. In this study, we profiled the concentrations of 143 lipid metabolites in dry blood spots (DBS) of RYGB patients. DBS from obese patients (BMI range 35&ndash, 44 kg/m2) were collected 7 days before, 15 and 90 days after the surgery. LC-MS/MS was used to quantify acylcarnitines, phosphatidylcholines, sphingomyelins and bile acids. RYGB caused a rapid increase in acylcarnitine levels that proved to be only transient, contrasting with the sustained decrease in phosphatidylcholines and increase of sphingomyelins and bile acids. A PLS-DA analysis revealed a 3-component model (R2 = 0.9, Q2 = 0.74) with key metabolites responsible for the overall metabolite differences. These included the BCAA-derived acylcarnitines and sphingomyelins with 16 and 18 carbons. We found important correlations between the levels of BCAA-derived acylcarnitines and specific sphingomyelins with plasma cholesterol and triacylglycerol concentrations. Along with the marked weight loss and clinical improvements, RYGB induced specific alterations in plasma acylcarnitines, bile acid and phospholipid levels. This calls for more studies on RYGB effects aiming to elucidate the metabolic adaptations that follow this procedure.

Health has been defined as the capability of the organism to adapt to challenges. In this study, we tested to what extent comprehensively phenotyped individuals reveal differences in metabolic responses to a standardized mixed meal tolerance test (MMTT) and how these responses change when individuals experience moderate weight loss. Metabolome analysis was used in 70 healthy individuals. with profiling of ∼300 plasma metabolites during an MMTT over 8 h. Multivariate analysis of plasma markers of fatty acid catabolism identified 2 distinct metabotype clusters (A and B). Individuals from metabotype B showed slower glucose clearance, had increased intra-abdominal adipose tissue mass and higher hepatic lipid levels when compared with individuals from metabotype A. An NMR-based urine analysis revealed that these individuals also to have a less healthy dietary pattern. After a weight loss of ∼5.6 kg over 12 wk, only the subjects from metabotype B showed positive changes in the glycemic response during the MMTT and in markers of metabolic diseases. Our study in healthy individuals demonstrates that more comprehensive phenotyping can reveal discrete metabotypes with different outcomes in a dietary intervention and that markers of lipid catabolism in plasma could allow early detection of the metabolic syndrome.-Fiamoncini, J., Rundle, M., Gibbons, H., Thomas, E. L., Geillinger-Kastle, K., Bunzel, D., Trezzi, J.-P., Kiselova-Kaneva, Y., Wopereis, S., Wahrheit, J., Kulling, S. E., Hiller, K., Sonntag, D., Ivanova, D., van Ommen, B., Frost, G., Brennan, L., Bell, J. Daniel, H. Plasma metabolome analysis identifies distinct human metabotypes in the postprandial state with different susceptibility to weight loss-mediated metabolic improvements.

Despite being well absorbed and displaying a range of biological properties, dietary terpenoids have been little studied. Better knowledge about their metabolism will help understanding the health effects of plant foods and provide information on the food metabolome. As part of the FoodBAll project we are investigating the metabolism of terpenes, identifying metabolites and biotransformations involved in their metabolism. PhytoHub (database that compiles all known metabolites of dietary phytochemicals, including terpenes) and Nexus Meteor (in silico prediction of metabolism), were used to identify biotransformations involved in the metabolism of dietary terpenoids. Selected biotransformations were used to predict the metabolism of camphene, camphor, carvacrol, carvone, caryophyllene, 1,4-cineole, 1,8-cineole, citral, citronellal, cuminaldehyde, p-cymene, fenchone, geraniol, limonene, linalool, menthol, myrcene, nootkatone, perillyl alcohol, pinene, pulegone, terpinen-4-ol and thymol. The metabolism prediction tool “BioTransformer” that is under development at Dr. Wishart’s lab was also used to generate predicted metabolites of the mentioned compounds. The urine of Wistar rats was collected before and after 5 days of the exposure to the dietary monoterpenes (given in the dose of 0.05% of diet). Untargeted metabolomics analysis was performed in urine using high-resolution mass spectrometry (UPLC-QToF). We identified twenty-two enzymatic reactions involved in the synthesis of terpenoid metabolites described in the literature. In average, 10 metabolites per compound were identified in rat urine, including new and known ones. Identification of metabolites was based on monoisotopic mass and formula match, presence of adducts and specific mass losses indicative of glucuronidation, sulphation and conjugation to amino acids. Validation of identification is being done using MS/MS experiments. The combination of in silico predictions and in vivo experiment allowed the identification of known and new metabolites of different dietary terpenoids. Predicted metabolites of terpenes will be added in databases such as PhytoHub to complement the database of known metabolites. The validations of the metabolism predictions are helping the development of BioTransformer. Funding: Grant from the Agence Nationale de la Recherche (#ANR-14-HDHL-0002-02) for FoodBAll project (JPI HDHL). JF is an AgreenSkills fellow.

Selenium is an essential trace element and mediates its functions via various selenoproteins such as glutathione peroxidases or thioredoxin reductases. A suboptimal selenium supply causes metabolic disturbances and is associated with an increased risk to develop different disorders, including cancer or cardiovascular diseases. This study aimed to assess the impact of a suboptimal selenium status on the hepatic metabolome of male mice analyzed by a targeted liquid chromatography/tandem mass spectrometry and a method based on non-targeted gas chromatography hyphenated with mass spectrometry. Feeding animals a diet with about half of the recommended selenium content supplied as selenomethionine caused liver glutathione peroxidase and thioredoxin reductase activities to decline and lipid peroxidation to increase. Serum T3 thyroid hormone concentration also declined via a reduced hepatic deiodinase activity. Metabolite profiling revealed predominantly changes in cysteine and carbon-1 metabolism as well as in selected lipid subclasses. In particular the concentrations of palmitoylcarnitines and oleoylcarnitines (C18:1 and C16:1) and various phosphatidylcholine species containing saturated fatty acids were elevated. Increased taurine levels suggested an enhanced cysteine flux through the salvage pathway whereas increased homocysteine levels appeared to be a consequence of a massive down-regulation of cystathionine β lyase (cystathionine β synthase) and a reduced flux through the transsulfuration pathway. The findings demonstrate that a suboptimal selenium status causes alterations in lipid and carbon-1 metabolism in mouse liver. These changes may contribute to the development of diseases associated with a suboptimal selenium status.

Retinopathy, a common complication of diabetes, is characterized by an unbalanced production of nitric oxide (NO), a process regulated by nitric oxide synthase (NOS). We hypothesized that retinopathy might stem from changes in the insulin receptor substrate (IRS)/PI3K/AKT pathway and/or expression of NOS isoforms. Thus, we analysed the morphology and apoptosis index in retinas of obese rats in whom insulin resistance had been induced by a high-fat diet (HFD). Immunoblotting analysis revealed that the retinal tissue of HFD rats had lower levels of AKT(1) , eNOS and nNOS protein than those of samples taken from control animals. Furthermore, immunohistochemical analyses indicated higher levels of iNOS and 4-hydroxynonenal and a larger number of apoptotic nuclei in HFD rats. Finally, both the inner and outer retinal layers of HFD rats were thinner than those in their control counterparts. When considered alongside previous results, these patterns suggest two major ways in which HFD might impact animals: direct activity of ingested fatty acids and/or via insulin-resistance-induced changes in intracellular pathways. We discuss these possibilities in further detail and advocate the use of this animal model for further understanding relationships between retinopathy, metabolic syndrome and type 2 diabetes.

Fatty acid (FA) composition of nine organs from two closely related Antarctic fish species, Notothenia coriiceps and Notothenia rossii , was determined through gas chromatography with flame ionization detection. A data set for each species was obtained using major FA profiles from specimens caught in the sea waters of Admiralty Bay during the summer season. The FA profiles for both species are overall similar, but organ peculiarities have been found, which could reflect metabolic specificities and feeding habits between species. With the exception of liver, the most abundant FA in organs was the n− 3 polyunsaturated FA. The total n− 6 polyunsaturated FAs were minor components in all evaluated organs. Palmitic acid was identified as the major saturated FA, whereas oleic acid was the most represented of the monounsaturated FA in almost all assessed organs of both species. The n − 3/ n − 6 ratios of all organs were higher than 3.5. Differences in individual FA and FA metabolic profiles of some organs observed between N. coriiceps and N. rossii suggest specific requirements in the mobilization, transport, incorporation, and/or catabolism of lipids that were reinforced by differences on some FA ratios expressing the activity coefficient of enzymes implicated on the FA pathway flux.

Glycogen content of white and red skeletal muscles, cardiac muscle, and liver was investigated in conditions where changes in plasma levels of non-esterified fatty acids (NEFA) occur. The experiments were performed in fed and 12 and 48 h-fasted rats. The animals were also submitted to swimming for 10 and 30 min. Glycogen content was also investigated in both pharmacologically induced low plasma NEFA levels fasted rats and pharmacologically induced high plasma NEFA levels fed rats. The participation of Akt and glycogen synthase kinase-3 (GSK-3) in the changes observed was investigated. Plasma levels of NEFA, glucose, and insulin were determined in all conditions. Fasting increased plasma NEFA levels and reduced glycogen content in the liver and skeletal muscles. However, an increase of glycogen content was observed in the heart under this condition. Akt and GSK-3 phosphorylation was reduced during fasting in the liver and skeletal muscles but it remained unchanged in the heart. Our results suggest that in conditions of increased plasma NEFA levels, changes in insulin-stimulated phosphorylation of Akt and GSK-3 and glycogen content vary differently in liver, skeletal muscles, and heart. Akt and GSK-3 phosphorylation and glycogen content are decreased in liver and skeletal muscles, but in the heart it remain unchanged (Akt and GSK-3 phosphorylation) or increased (glycogen content) due to consistent increase of plasma NEFA levels.

Foi avaliado o perfil dos ácidos graxos da gordura intramuscular do Longissimus dorsi de vacas de descarte mestiças, da segunda (G2 - 3/4Charolês (C) 1/4Nelore (N) e 3/4NC) e da terceira geração (G3 - 5/8CN e 5/8NC) de cruzamento rotativo Charolês - Nelore, terminadas em confinamento e abatidas com 465, 507 ou 566kg. Os animais apresentaram, na média, no início do confinamento, 8,5 anos, 388,6kg e 2,35 pontos de escore da condição corporal. A dieta alimentar, relação volumoso:concentrado de 48:52, continha 12,5% de proteína bruta e 2,99Mcal de energia digestível por kg de matéria seca. Os ácidos graxos saturados C14:0 (merístico) e C16:0 (palmítico) reduziram as suas participações em 19 e 10%, respectivamente, com o aumento do peso de abate de 465 para 566kg, mesmo comportamento observado para o C 18:0 (esteárico). Houve menor representação dos ácidos saturados em detrimento aos insaturados com o incremento do peso de abate, sendo a associação negativa (r=-0,61; P

Apart from their role in lipid digestion and sterol homeostasis, bile acids (BA) are known to affect metabolism via FXR and TGR5 receptors. They also modulate energy expenditure and thus became a t...

Omega-3 polyunsaturated fatty acids (n-3 PUFA) found in fish oil activate PPAR-?, stimulate peroxisomal fatty acid (FA) ?-oxidation and prevent impairments on glucose homeostasis.Glucose metabolism and FA oxidation were studied in C57/Bl6 mice fed with diets containing either 3.6 and 31.5% fish oil or lard. To assess the effects of peroxisomal proliferation on FA oxidation independent of n-3 PUFA intake, mice were treated with the PPAR-? agonist WY-14643. n-3 PUFA-fed mice were protected from glucose intolerance and dyslipidemia compared to animals fed a lard-based high-fat diet. Most importantly, mice fed on the hyperlipidic diet based on fish oil as well as the WY-14643 treated mice showed twofold increase of odd, medium-chain, dicarboxylic acylcarnitines in the liver suggesting that not only ?-oxidation, but also ?- and ?-oxidation of FA were increased. Finally, an oxidation assay using liver homogenates and palmitic acid as substrate revealed an over tenfold increased production of similar acylcarnitines, indicating that FA are their precursors.This study shows at the metabolite level that peroxisome proliferation induced either by fish oil or WY-14643 is associated with increased ?- and ?-oxidation of FA producing specific acylcarnitines that can be utilized as biomarkers of peroxisomal FA oxidation.

We investigated the effect of fish oil supplementation for two consecutive generations on insulin sensitivity in rats. After the nursing period (21 days), female rats from the same prole were divided into two groups: (a) control group and (b) fish oil group. Female rats were supplemented with water (control) or fish oil at 1 g/kg body weight as a single bolus for 3 months. After this period, female rats were mated with male Wistar rats fed on a balanced chow diet (not supplemented). Female rats continued to receive supplementation throughout gestation and lactation periods. The same treatment was performed for the next two generations (G1 and G2). At 75 days of age, male offspring from G1 and G2 generations from both groups were used in the experiments. G1 rats did not present any difference with control rats. However, G2 rats presented reduction in glycemia and lipidemia and improvement in in vivo insulin sensitivity (model assessment of insulin resistance, insulin tolerance test) as well as in vitro insulin sensitivity in soleus muscle (glucose uptake and metabolism). This effect was associated with increased insulin-stimulated p38 MAP kinase phosphorylation and lower n-6/n-3 fatty acid ratio, but not with activation of proteins from insulin signaling (IR, IRS-1 and Akt). Global DNA methylation was decreased in liver but not in soleus muscle. These results suggest that long-term fish oil supplementation improves insulin sensitivity in association with increased insulin-stimulated p38 activation and decreased n-6:n-3 ratio in skeletal muscle and decreased global DNA methylation in liver.

Foram avaliados o perfil dos ácidos graxos da gordura intramuscular e a qualidade da carne de vacas de descarte terminadas em confinamento recebendo dietas sem ou com monensina sódica (200mg animal-1 dia-1). A dieta continha 12,5% de proteína bruta e 2,99Mcal de energia digestível kg-1 de matéria seca, composta de 48% de volumoso (silagem de milho) e 52% de concentrado. A presença de monensina não teve efeito significativo sobre a cor, a textura e o marmoreio, apresentando valores médios de 3,55; 3,29 e 6,38 pontos, respectivamente. Quanto às características sensoriais, a carne dos animais alimentados com monensina demonstra ser menos palatável (P