Involvement of autophagy in the beneficial effects of resveratrol in hepatic steatosis treatment. A comparison with energy restriction.

Autophagy eliminates damaged cellular components. In the liver, it has been proposed that it mediates the breakdown of lipid droplets. This study aimed to compare the involvement of autophagy and the oxidative status in the effects of resveratrol and energy restriction as therapeutic tools for managing liver steatosis. In addition, potential additive or synergic effects were studied. Rats were fed a high-fat high-sucrose diet for 6 weeks and then divided into four experimental groups and fed a standard diet: a control group (C), a resveratrol-treated group (RSV, 30 mg kg-1 d-1), an energy restricted group (R, -15%), and an energy restricted group treated with resveratrol (RR). Liver triacylglycerols (TGs) were measured by Folch's method. TBARS, GSH, GSSG, GPx and SOD were assessed using commercial kits. The protein expression of beclin, atg5 and p62, as well as ratios of pSer555 ULK1/total ULK1, pSer757 ULK1/total ULK1 and LC3 II/I were determined by western blotting. Energy restriction increased the protein expression of beclin, atg5 and pSer757 ULK1/total ULK1 and LC3 II/I ratios, and reduced the protein expression of p62, thus indicating that it induced autophagy activation. The effects of resveratrol were similar but less marked than the hypocaloric diet. No differences were observed in oxidative stress determinants except for TBARS, which was decreased by energy restriction. In conclusion, resveratrol can reverse partially dietary-induced hepatic lipid accumulation, although less efficiently than energy restriction. The delipidating effect of energy restriction is mediated in part by the activation of autophagy; however, the involvement of this process in the effects of resveratrol is less clear.

Comparative effects of energy restriction and resveratrol intake on glycemic control improvement.

Resveratrol (RSV) has been proposed as an energy restriction mimetic. This study aimed to compare the effects of RSV and energy restriction on insulin resistance induced by an obesogenic diet. Any additive effect of both treatments was also analyzed. Rats were fed a high-fat high-sucrose diet for 6 weeks. They were then distributed in four experimental groups which were either fed a standard control diet (C), or treated with RSV (30 mg/kg/d), or submitted to energy restriction (R, 15%), or treated with RSV and submitted to energy restriction (RR). A glucose tolerance test was performed, and serum glucose, insulin, fructosamine, adiponectin, and leptin concentrations determined. Muscle triacylglycerol content and protein expression of insulin receptor (IRß), protein kinase B (Akt), Akt substrate of 160 kDa (AS160) and glucose transporter 4 (GLUT-4) were measured. In RSV rats, fructosamine concentrations were reduced, HOMA-IR remained unchanged, but glucose tolerance was improved, without changes in phosphorylation of IRß, Akt, and AS160 or in GLUT-4 protein expression. Rats under energy restriction showed an improvement in all the markers related to glycemic control, as well as increased phosphorylation of AS160 and protein expression of GLUT-4. In rats from RR group the results were similar to R group, with the exception of IRß and Akt phosphorylation, which were increased. In conclusion, mild energy restriction is more efficient than intake of RSV within a standard balanced diet, and acts by means of a different mechanism from that of RSV. No additive effects between RSV and energy restriction were observed. © 2017 BioFactors, 43(3):371-378, 2017.

Papel en la obesidad de la microbiota intestinal / Role of gut microbiota in obesity

La contribución de la microbiota intestinal al desarrollo de diversas enfermedades, incluyendo la obesidad, se está estudiando minuciosamente. Aunque los mecanismos no están completamente definidos, las perturbaciones en la composición de la microbiota intestinal parecen estar relacionados con el sobrepeso, revelando alteraciones en los niveles de Bacteriodetes y Firmicutes en comparación con individuos delgados. La modulación de la comunidad bacteriana intestinal orientada a favorecer el crecimiento de bacterias ‘saludables’ y reducir las dañinas podría ser una eficaz herramienta terapéutica contra la obesidad. El consumo de dietas con alto contenido en grasa y azúcares afecta notablemente a la composición de la microbiota, alterando su equilibrio hacia patrones asociados a obesidad, siendo un punto de partida para un tratamiento de precisión de esta enfermedad. La interacción entre componentes de la dieta y la microbiota intestinal podría ser, en parte, responsable de sus beneficios para la salud, por lo que la administración de compuestos bioactivos podría promover el crecimiento de bacterias beneficiosas en detrimento de otras patógenas o asociadas a la obesidad. El impacto sobre el metaboloma de las intervenciones dietéticas y la administración de polifenoles se podría identificar mediante metabolómica no dirigida de las heces, permitiendo estratificar los individuos en función de la intervención dietética con el fin de aplicar tratamientos personalizados. Esta revisión pretende proporcionar una instantánea de este sistema complejo que comprende microbiota intestinal, dieta, polifenoles, metabolismo del individuo y obesidad, y cuyo conocimiento se beneficia de tecnologías avanzadas como la secuenciación de última generación y la metabolómica no dirigida (AU)

The contribution of the gut microbiota to the development of many diseases, including obesity, is being thoroughly explored. Although mechanisms are not fully understood, perturbations on gut microbiota composition seem to be related to overweight. Indeed, subjects with excessive body weight, show impairment in intestinal levels of Bacteriodetes and Firmicutes as compared to lean individuals. Therefore, modulation of gut bacterial community with approaches that could enhance the growth of ‘healthy’ bacteria and reduce harmful bacteria might be an effective therapeutic tool against obesity. Bi-directional interactions between natural compounds and the gut microbiota taking place at intestinal level, has been hypothesized to be partly responsible for the health beneficial outcomes. The consumption of high-fat high-sucrose diets strongly impacts gut microbiota composition impairing the bacterial balance towards an obesity-associated gut microbial pattern, which may be the basis for a precision management of obesity. Remarkably, the administration of bioactive compounds could counteract the disturbance of gut microbiota related to diet-induced obesity, promoting the growth of some beneficial bacteria while reducing some pathogenic and obesity- associated microbes. Biological outcomes exerted by dietary interventions and polyphenol administration on global host metabolome might be distinguished through a faecal non-targeted metabolomic analysis, where individuals might be also stratified in different groups based on the dietary intervention for personalized treatments . Therefore, this overview aimed to provide a snapshot of this complex system consisting of gut microbiota, diet and polyphenols, host metabolism and obesity taking advantage of advanced technologies namely next-generation sequencing and untargeted metabolomics (AU)

Trans-resveratrol induces a potential anti-lipogenic effect in lipopolysaccharide-stimulated enterocytes.

A DNA microarray analysis was conducted in Caco-2 cells to analyse the protective effects of trans-resveratrol on enterocyte physiology and metabolism in pro-inflammatory conditions. Cells were pre-treated with 50 µΜ of trans-resveratrol and, subsequently, lipopolysaccharide (LPS) was added for 48 h. The microarray analysis revealed 121 genes differentially expressed between resveratrol-treated and non-treated cells (B> 0, is the odd thatthe gene is differentially expressed). Inhibitor of DNA binding 1 (ID1), histidine-rich glycoprotein (HRG), NADPH oxidase (NOX1) and sprouty homolog 1 (SPRY), were upregulated by LPS treatment, but significantly blocked by trans-resveratrol pre-treatment (padj< 0.05, after adjusting for Benjamini-Hocheberg procedure). Moreover, genes implicated in synthesis of lipids (z-score= -1.195) and concentration of cholesterol (z-score= -0.109), were markedly downregulated by trans-resveratrol. Other genes involved in fat turnover, but also in cell death and survival function, such as transcription factors Krüppel-like factor 5 (KLF5) and amphiregulin (AREG), were also significantly inhibited by trans-resveratrol pre-treatment. RT-qPCR-data confirmed the microarray results. Special mention deserves acyl-CoA synthetase long-chain family member 3 (ACSL3) and endothelial lipase (LIPG), which were downregulated by this stilbene and have been previously associated with fatty acid synthesis and obesity in other tissues. This study envisages that trans-resveratrol might exert an important anti-lipogenic effect at intestinal level under pro-inflammatory conditions, which has not been previously described.

Reshaping faecal gut microbiota composition by the intake of trans-resveratrol and quercetin in high-fat sucrose diet-fed rats.

Diet-induced obesity is associated to an imbalance in the normal gut microbiota composition. Resveratrol and quercetin, widely known for their health beneficial properties, have low bioavailability, and when they reach the colon, they are targets of the gut microbial ecosystem. Hence, the use of these molecules in obesity might be considered as a potential strategy to modulate intestinal bacterial composition. The purpose of this study was to determine whether trans-resveratrol and quercetin administration could counteract gut microbiota dysbiosis produced by high-fat sucrose diet (HFS) and, in turn, improve gut health. Wistar rats were randomised into four groups fed an HFS diet supplemented or not with trans-resveratrol [15 mg/kg body weight (BW)/day], quercetin (30 mg/kg BW/day) or a combination of both polyphenols at those doses. Administration of both polyphenols together prevented body weight gain and reduced serum insulin levels. Moreover, individual supplementation of trans-resveratrol and quercetin effectively reduced serum insulin levels and insulin resistance. Quercetin supplementation generated a great impact on gut microbiota composition at different taxonomic levels, attenuating Firmicutes/Bacteroidetes ratio and inhibiting the growth of bacterial species previously associated to diet-induced obesity (Erysipelotrichaceae, Bacillus, Eubacterium cylindroides). Overall, the administration of quercetin was found to be effective in lessening HFS-diet-induced gut microbiota dysbiosis. In contrast, trans-resveratrol supplementation alone or in combination with quercetin scarcely modified the profile of gut bacteria but acted at the intestinal level, altering the mRNA expression of tight-junction proteins and inflammation-associated genes.

Shifts in microbiota species and fermentation products in a dietary model enriched in fat and sucrose.

The gastrointestinal tract harbours a 'superorganism' called the gut microbiota, which is known to play a crucial role in the onset and development of diverse diseases. This internal ecosystem, far from being a static environment, can be manipulated by diet and dietary components. Feeding animals with high-fat sucrose (HFS) diets entails diet-induced obesity, a model which is usually used in research to mimic the obese phenotype of Western societies. The aim of the present study was to identify gut microbiota dysbiosis and associated metabolic changes produced in male Wistar rats fed a HFS diet for 6 weeks and compare it with the basal microbial composition. For this purpose, DNA extracted from faeces at baseline and after treatment was analysed by amplification of the V4-V6 region of the 16S ribosomal DNA (rDNA) gene using 454 pyrosequencing. Short-chain fatty acids, i.e. acetate, propionate and butyrate, were also evaluated by gas chromatography-mass spectrometry. At the end of the treatment, gut microbiota composition significantly differed at phylum level (Firmicutes, Bacteroidetes and Proteobacteria) and class level (Erisypelotrichi, Deltaproteobacteria, Bacteroidia and Bacilli). Interestingly, the class Clostridia showed a significant decrease after HFS diet treatment, which correlated with visceral adipose tissue, and is likely mediated by dietary carbohydrates. Of particular interest, Clostridium cluster XIVa species were significantly reduced and changes were identified in the relative abundance of other specific bacterial species (Mitsuokella jalaludinii, Eubacterium ventriosum, Clostridium sp. FCB90-3, Prevotella nanceiensis, Clostridium fusiformis, Clostridium sp. BNL1100 and Eubacterium cylindroides) that, in some cases, showed opposite trends to their relative families. These results highlight the relevance of characterising gut microbial population differences at species level and contribute to understand the plausible link between diet and specific gut bacterial species that are able to influence the inflammatory status, intestinal barrier function and obesity development.

Diet-induced hyperinsulinemia differentially affects glucose and protein metabolism: a high-throughput metabolomic approach in rats

Metabolomics is a high-throughput tool that quantifies and identifies the complete set of biofluid metabolites. This “omics” science is playing an increasing role in understanding the mechanisms involved in disease progression. The aim of this study was to determine whether a nontargeted metabolomic approach could be applied to investigate metabolic differences between obese rats fed a high-fat sucrose (HFS) diet for 9 weeks and control diet-fed rats. Animals fed with the HFS diet became obese, hyperleptinemic, hyperglycemic, hyperinsulinemic, and resistant to insulin. Serum samples of overnight-fasted animals were analyzed by 1H NMR technique, and 49 metabolites were identified and quantified. The biochemical changes observed suggest that major metabolic processes like carbohydrate metabolism, Beta-oxidation, tricarboxylic acid cycle, Kennedy pathway, and folate-mediated one-carbon metabolism were altered in obese rats. The circulating levels of most amino acids were lower in obese animals. Serum levels of docosahexaenoic acid, linoleic acid, unsaturated n-6 fatty acids, and total polyunsaturated fatty acids also decreased in HFS-fed rats. The circulating levels of urea, six water-soluble metabolites (creatine, creatinine, choline, acetyl carnitine, formate, and allantoin), and two lipid compounds (phosphatidylcholines and sphingomyelin) were also significantly reduced by the HFS diet intake. This study offers further insight of the possible mechanisms implicated in the development of diet-induced obesity. It suggests that the HFS diet-induced hyperinsulinemia is responsible for the decrease in the circulating levels of urea, creatinine, and many amino acids, despite an increase in serum glucose levels (AU)

Diet-induced hyperinsulinemia differentially affects glucose and protein metabolism: a high-throughput metabolomic approach in rats.

Metabolomics is a high-throughput tool that quantifies and identifies the complete set of biofluid metabolites. This "omics" science is playing an increasing role in understanding the mechanisms involved in disease progression. The aim of this study was to determine whether a nontargeted metabolomic approach could be applied to investigate metabolic differences between obese rats fed a high-fat sucrose (HFS) diet for 9 weeks and control diet-fed rats. Animals fed with the HFS diet became obese, hyperleptinemic, hyperglycemic, hyperinsulinemic, and resistant to insulin. Serum samples of overnight-fasted animals were analyzed by (1)H NMR technique, and 49 metabolites were identified and quantified. The biochemical changes observed suggest that major metabolic processes like carbohydrate metabolism, ß-oxidation, tricarboxylic acid cycle, Kennedy pathway, and folate-mediated one-carbon metabolism were altered in obese rats. The circulating levels of most amino acids were lower in obese animals. Serum levels of docosahexaenoic acid, linoleic acid, unsaturated n-6 fatty acids, and total polyunsaturated fatty acids also decreased in HFS-fed rats. The circulating levels of urea, six water-soluble metabolites (creatine, creatinine, choline, acetyl carnitine, formate, and allantoin), and two lipid compounds (phosphatidylcholines and sphingomyelin) were also significantly reduced by the HFS diet intake. This study offers further insight of the possible mechanisms implicated in the development of diet-induced obesity. It suggests that the HFS diet-induced hyperinsulinemia is responsible for the decrease in the circulating levels of urea, creatinine, and many amino acids, despite an increase in serum glucose levels.

Resultados de la intervención farmacéutica en la dosificación de zoledronato en función del aclaramiento de creatinina estimado / No disponible

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