Pterostilbene modifies triglyceride metabolism in hepatic steatosis induced by high-fat high-fructose feeding: a comparison with its analog resveratrol.

The use of phenolic compounds as a new therapeutic approach against NAFLD has emerged recently. In the present study, we aim to study the effect of pterostilbene in the prevention of liver steatosis developed as a consequence of high-fat (saturated) high-fructose feeding, by analysing the changes induced in metabolic pathways involved in triglyceride accumulation. Interestingly, a comparison with the anti-steatotic effect of its parent compound resveratrol will be made for the first time. Rats were distributed into 5 experimental groups and fed either a standard laboratory diet or a high-fat high-fructose diet supplemented with or without pterostilbene (15 or 30 mg per kg per d) or resveratrol (30 mg per kg per d) for 8 weeks. Serum triglyceride, cholesterol, NEFA and transaminase levels were quantified. Liver histological analysis was carried out by haematoxylin-eosin staining. Different pathways involved in liver triglyceride metabolism, including fatty acid synthesis, uptake and oxidation, triglyceride assembly and triglyceride release, were studied. Pterostilbene was shown to partially prevent high-fat high-fructose feeding induced liver steatosis in rats, demonstrating a dose-response pattern. In this dietary model, it acts mainly by reducing de novo lipogenesis and increasing triglyceride assembly and release. Improvement in mitochondrial functionality was also appreciated. At the same dose, the magnitude of pterostilbene and resveratrol induced effects, as well as the involved mechanisms of action, were similar.

Effects of resveratrol and its derivative pterostilbene on brown adipose tissue thermogenic activation and on white adipose tissue browning process.

The main function of brown adipose tissue (BAT) is thermogenesis, a process mediated by uncoupling protein 1 (UCP1), which is located in the inner mitochondrial membrane and acts uncoupling oxidative phosphorylation from ATP production, thereby dissipating energy as heat. White adipose tissue can also express UCP1 positive cells due to a process known as browning. This phenomenon could also increase the thermogenic effect in the classical brown adipose depots. BAT thermogenesis depends, among other factors on both, nutritional conditions and food availability. Indeed, some studies have found that BAT recruitment and function are enhanced by some food components. The present study focuses on the effects of resveratrol and pterostilbene, two phenolic compounds belonging to the stilbene group, on BAT thermogenic activation and white adipose tissue browning process. The reported studies, carried out in cell cultures and animal models, show that both resveratrol and pterostilbene induce thermogenic capacity in interscapular BAT by increasing mitochondriogenesis, as well as enhancing fatty acid oxidation and glucose disposal. In addition, resveratrol seems to promote browning by activating peroxisome proliferator-activated receptor (PPAR), while the lack of changes in mitochondrial biogenesis suggests that probably the browning process occurs by direct resveratrol-mediated upregulation of ucp1 mRNA expression.

MicroRNAs involved in the browning process of adipocytes

The present review focuses on the role of miRNAs in the control of white adipose tissue browning, a process which describes the recruitment of adipocytes showing features of brown adipocytes in white adipose tissue. MicroRNAs (miRNAs) are a class of short non-coding RNAs (19-22 nucleotides) involved in gene regulation. Although the main effect of miRNAs is the inhibition of the translational machinery, thereby preventing the production of the protein product, the activation of protein translation has also been described in the literature. In addition to modifying translation, miRNAs binding to its target mRNAs also trigger the recruitment and association of mRNA decay factors, leading to mRNA destabilization, degradation, and thus to the decrease in expression levels. Although a great number of miRNAs have been reported to potentially regulate genes that play important roles in the browning process, only a reduced number of studies have demonstrated experimentally an effect on this process associated to changes in miRNA expressions, so far. These studies have shown, by using either primary adipocyte cultures or experimental models of mice (KO mice, mice overexpressing a specific miRNA) that miR-196a, miR-26 and miR-30 are needed for browning process development. By contrast, miR-155, miR-133, miR-27b and miR-34 act as negative regulators of this process. Further studies are needed to fully describe the miRNA network-involved white adipose tissue browning regulation (AU)

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Erratum to: MicroRNAs involved in the browning process of adipocytes

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MicroRNAs involved in the browning process of adipocytes.

The present review focuses on the role of miRNAs in the control of white adipose tissue browning, a process which describes the recruitment of adipocytes showing features of brown adipocytes in white adipose tissue. MicroRNAs (miRNAs) are a class of short non-coding RNAs (19-22 nucleotides) involved in gene regulation. Although the main effect of miRNAs is the inhibition of the translational machinery, thereby preventing the production of the protein product, the activation of protein translation has also been described in the literature. In addition to modifying translation, miRNAs binding to its target mRNAs also trigger the recruitment and association of mRNA decay factors, leading to mRNA destabilization, degradation, and thus to the decrease in expression levels. Although a great number of miRNAs have been reported to potentially regulate genes that play important roles in the browning process, only a reduced number of studies have demonstrated experimentally an effect on this process associated to changes in miRNA expressions, so far. These studies have shown, by using either primary adipocyte cultures or experimental models of mice (KO mice, mice overexpressing a specific miRNA), that miR-196a, miR-26, and miR-30 are needed for browning process development. By contrast, miR-155, miR-133, miR-27b, and miR-34 act as negative regulators of this process [corrected]. Further studies are needed to fully describe the miRNA network-involved white adipose tissue browning regulation.

Pterostilbene improves glycaemic control in rats fed an obesogenic diet: involvement of skeletal muscle and liver.

This study aims to determine whether pterostilbene improves glycaemic control in rats showing insulin resistance induced by an obesogenic diet. Rats were divided into 3 groups: the control group and two groups treated with either 15 mg kg(-1) d(-1) (PT15) or 30 mg kg(-1) d(-1) of pterostilbene (PT30). HOMA-IR was decreased in both pterostilbene-treated groups, but this reduction was greater in the PT15 group (-45% and -22% respectively vs. the control group). The improvement of glycaemic control was not due to a delipidating effect of pterostilbene on skeletal muscle. In contrast, GLUT4 protein expression was increased (+58% and +52% vs. the control group), suggesting an improved glucose uptake. The phosphorylated-Akt/total Akt ratio was significantly enhanced in the PT30 group (+25%), and therefore a more efficient translocation of GLUT4 is likely. Additionally, in this group the amount of cardiotrophin-1 was significantly increased (+65%). These data suggest that the effect of pterostilbene on Akt is mediated by this cytokine. In the liver, glucokinase activity was significantly increased only in the PT15 group (+34%), and no changes were observed in glucose-6-phosphatase activity. The beneficial effect of pterostilbene on glycaemic control was more evident with the lower dose, probably because in the PT15 group both the muscle and the liver were contributing to this effect, but in the PT30 group only the skeletal muscle was responsible. In conclusion, pterostilbene improves glycaemic control in rats showing insulin resistance induced by an obesogenic diet. An increase in hepatic glucokinase activity, as well as in skeletal muscle glucose uptake, seems to be involved in the anti-diabetic effect of this phenolic compound.

Potential application of non-flavonoid phenolics in diabetes: antiinflammatory effects.

Polyphenols are members of a very large family of plant-derived compounds that may have beneficial effects on human health, and thus their study has become an increasingly important area of human nutrition research. Considering that it is increasingly accepted that chronic sub-acute inflammation plays an important role in the development of insulin resistance and of diabetes in animals and in humans, the aim of the present review is to compile information concerning the anti-inflammatory effects of non-flavonoid polyphenols on diabetes prevention and/or treatment. Most of these studies have been carried out with different cultured cells and using animal models displaying different types of diabetes, such as diabetes induced by streptozotocin or streptozotocin-nicotinamide, genetic diabetes or diabetes induced by high-fat feeding. In general terms, non-flavonoid polyphenols reduce the production of inflammatory mediators, such as IL-1ß, IL-8, MCP-1, COX-2 or iNOS in these animal models of diabetes. This effect is accompanied in the vast majority of these studies by improved insulin action. In addition, some of the non-flavonoid polyphenols are also able to ameliorate or prevent several pathological alterations associated with the development of diabetes, such as nephropathy, cardiopathy or retinopathy. Very little information has been reported with regard to human studies to date. Thus, new studies are needed to confirm if the beneficial effects observed in preclinical studies can apply to human beings.

The combination of resveratrol and conjugated linoleic acid attenuates the individual effects of these molecules on triacylglycerol metabolism in adipose tissue.

PURPOSE: The combination of resveratrol + conjugated linoleic acid (RSV + CLA) did not show the body fat-lowering effect exhibited by these molecules when administered separately. This study aimed to find metabolic explanations for this situation in an experimental model of diet-induced obesity. METHODS: Thirty-six male Wistar rats were divided into four groups: rats treated with saline (control), resveratrol (RSV), conjugated linoleic acid (CLA) and a combination of these molecules (RSV + CLA). RESULTS: Rats treated with RSV + CLA did not show the reduction in heparin-releasable lipoprotein lipase (HR-LPL) and fatty acid synthase activities observed in RSV group or the increased HSL expression found in RSV and CLA groups. These animals showed reduced sirtuin 1 expression and CLA isomer amounts in adipose tissue. Finally, intracellular Ca(2+) concentration was increased. CONCLUSION: The attenuation of the effects induced in adipose tissue triacylglycerol metabolism by RSV and CLA separately, such as the decrease in lipogenesis and fatty acid uptake and the increase in lipolysis, contributes to explain the lack of body fat-lowering effect of the combination RSV + CLA.

Resveratrol attenuates steatosis in obese Zucker rats by decreasing fatty acid availability and reducing oxidative stress.

Non-alcoholic fatty liver disease (NAFLD) is one of the most common manifestations of chronic liver disease worldwide. The aim of the present study was to assess the effect of resveratrol on liver fat accumulation, as well as on the activity of those enzymes involved in lipogenesis and fatty acid oxidation in fa/fa Zucker rats. A total of thirty rats were assigned to three experimental groups and orally treated with resveratrol for 6 weeks, or without resveratrol (C: control group; RSV15 group: 15 mg/kg body weight per d; RSV45 group: 45 mg/kg body weight per d). Liver histological analysis was performed by microscopy. Levels of hepatic carnitine palmitoyltransferase-Ia (CPT-Ia), acyl-coenzyme A oxidase (ACO), fatty acid synthase, glucose-6-phosphate dehydrogenase and malic enzyme were assessed by spectrophotometry, and acetyl-CoA carboxylase was assessed by radiometry. Commercial kits were used to determine serum TAG, NEFA, total HDL and non-HDL-cholesterol, glycerol, ketonic bodies, glucose, insulin, adiponectin, aspartate aminotransferase (AST), alanine aminotransferase (ALT) and alkaline phosphatase (ALP), hepatic TAG, thiobarbituric acid reactive substrates, GSH (GSSG) and superoxide dismutase. Resveratrol reduced liver weight and TAG content. It did not modify the activity of lipogenic enzymes but it did increase CPT-Ia and ACO activities. NEFA and ALP were reduced in both resveratrol-treated groups. AST/GOT was reduced only by the lowest dose. ALT/GPT, TAG and adiponectin remained unchanged. Resveratrol reduced liver oxidative stress. This study demonstrates that resveratrol can protect the liver from NAFLD by reducing fatty acid availability. Moreover, resveratrol also protects liver from oxidative stress.

A comparison between CLNA and CLA effects on body fat, serum parameters and liver composition.

The potential of conjugated linoleic acid (CLA) as an anti-obesity molecule for humans is still a matter for debate. Thus, a great deal of scientific work is focussed on the research of new effective molecules without deleterious effects on health. The aim of the present work was to analyse the effects of jacaranda seed oil, rich in a conjugated linolenic acid (CLNA), jacaric acid (cis-8,trans-10,cis-12), on body fat, serum parameters and liver composition in rats, and to compare these effects with those of trans-10,cis-12 CLA. Twenty-six male Wistar rats were divided into three groups fed with high-fat diets, supplemented or not (control group) with 0.5% trans-10,cis-12 CLA (CLA group) or 0.5% jacaric acid (CLNA group) for 7 weeks. No statistical differences in food intake or in final body weight were found. Whereas CLA reduced adipose tissue size, CLNA did not. Both CLA and CLNA significantly reduced non-HDL-cholesterol. In spite of a lack of significant changes in glucose and insulin levels, HOMA-IR index was significantly increased, as well as did non-esterified fatty acid levels in CLNA-fed rats. No changes in liver composition were observed. In conclusion, under our experimental conditions, jacaric acid, unlike CLA, does not show a body-fat lowering effect. Even though it leads to a healthy lipoprotein profile, it impairs insulin function. Consequently, it cannot be proposed as an anti-obesity molecule.

Comparación entre los efectos de CLA y CLNA sobre la grasa corporal, parámetros séricos y composición del hígado / A comparison between CLNA and CLA effects on body fat, serum parameters and liver composition

The potential of conjugated linoleic acid (CLA) as an anti-obesity molecule forhumans is still a matter for debate. Thus, a great deal of scientific work is focussed onthe research of new effective molecules without deleterious effects on health. The aimof the present work was to analyse the effects of jacaranda seed oil, rich in a conjugatedlinolenic acid (CLNA), jacaric acid (cis-8,trans-10,cis-12), on body fat, serumparameters and liver composition in rats, and to compare these effects with those oftrans-10,cis-12 CLA. Twenty-six male Wistar rats were divided into three groups fedwith high-fat diets, supplemented or not (control group) with 0.5% trans-10,cis-12CLA (CLA group) or 0.5% jacaric acid (CLNA group) for 7 weeks. No statisticaldifferences in food intake or in final body weight were found. Whereas CLA reducedadipose tissue size, CLNA did not. Both CLA and CLNA significantly reduced non-HDL-cholesterol. In spite of a lack of significant changes in glucose and insulin levels,HOMA-IR index was significantly increased, as well as did non-esterified fattyacid levels in CLNA-fed rats. No changes in liver composition were observed. Inconclusion, under our experimental conditions, jacaric acid, unlike CLA, does notshow a body-fat lowering effect. Even though it leads to a healthy lipoprotein profile,it impairs insulin function. Consequently, it cannot be proposed as an anti-obesitymolecule(AU)

El potencial del ácido linoleico conjugado(CLA) como molécula anti-obesidad para sereshumanos sigue siendo una cuestión en debate.Por ello, gran cantidad de trabajos científicosse centra en la investigación de nuevas moléculaseficaces y sin efectos nocivos sobre la salud.El objetivo del presente trabajo fue estudiar, enrata, los efectos del aceite de semillas de jacaranda,rico en un ácido linolénico conjugado(CLNA), el ácido jacárico (cis-8,trans-10,cis-12), sobre la grasa corporal, parámetros séricosy la composición del hígado, y comparar estosefectos con los del trans-10,cis-12 CLA. Se utilizaron26 ratas Wistar macho divididas en tresgrupos que fueron alimentados durante 7semanas con dietas hipergrasas, suplementadaso no (grupo control) al 0,5% con el trans-10,cis-12 CLA (grupo CLA) o al 0,5% con elácido jacárico (grupo CLNA). No se encontrarondiferencias significativas en la ingesta dedieta, ni en el peso corporal final, ni en la composicióndel hígado. El CLA redujo la masaadiposa, pero no lo hizo el CLNA. Ambos disminuyeronsignificativamente el colesterol no-HDL. A pesar de la ausencia de cambios significativosen la glucemia e insulinemia, el índiceHOMA-IR y los niveles séricos de AGLaumentaron significativamente en las ratas alimentadascon CLNA. En conclusión, en nuestrascondiciones experimentales, el ácido jacárico,a diferencia del CLA, no muestra un efectoreductor de la grasa corporal. A pesar de quemejora el perfil de lipoproteínas, altera la funcióninsulínica. Por lo tanto, este CLNA nopuede ser propuesto como una molécula antiobesidad(AU)

Adiposity and serum parameters in hamsters fed energy restricted diets supplemented or not with trans-10, cis-12 conjugated linoleic acid

Numerous studies have demonstrated that conjugated linoleic acid (CLA) modulatesbody composition, reducing body fat accumulation in various mammalianspecies. However, very few studies have been carried out to assess the effect of CLAon previously stored body fat. The aim of the present work was to analyse the effectivenessof trans-10,cis-12 CLA in improving alterations produced by high-fat feedingin body fat and serum parameters when it was included in an energy-restricteddiet. For this purpose male Syrian Golden hamsters were fed on high-fat diet for 7weeks in order to increase their body fat content, and a further 25% energy-restricteddiet supplemented or not with 0.5% trans-10,cis-12 CLA for 3 weeks. Adipose tissues,liver and gastrocnemious muscles were dissected and weighed. Adipocyte diameterand number were assessed in epididymal adipose tissue. Total cholesterol, triacylglycerols,non-esterified fatty acids and glucose were measured in serum. Threeweeks of energy restriction resulted in a reduction in body weight and white adiposetissue size in all anatomical locations, without changes in liver and gastrocnemiousmuscle weights. Epididymal adipocyte size was reduced, but total adipocyte numberremained unchanged. Serum cholesterol, triacylglycerols and glucose were significantlyreduced. No differences were observed between the restricted groups (controland CLA supplemented). In conclusion, under our experimental conditions, theaddition of trans-10,cis-12 CLA to the diet does not increase the benefits producedby energy restriction (AU)

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Influence of acute and chronic administration of benzylamine on glucose tolerance in diabetic and obese mice fed on very high-fat diet

The combination of vanadate plus benzylamine has been reported to stimulateglucose transport in rodent adipocytes and to mimic other insulin actions in diversestudies. However, benzylamine alone activates glucose uptake in human fat cells andincreases glucose tolerance in rabbits. The aim of this work was to unravel the benzylamineantihyperglycemic action and to test whether its chronic oral administrationcould restore the defective glucose handling of mice rendered slightly obese anddiabetic by very high-fat diet (VHFD). When VHFD mice were i.p. injected withbenzylamine at 0.7 to 700 ìmol/kg before glucose tolerance test, they exhibitedreduced hyperglycemic response without alteration of insulin secretion. Whole bodyglucose turnover, as assessed by the glucose isotopic dilution technique, wasunchanged in mice perfused with benzylamine (total dose of 75 ìmol/kg). However,their in vivo glycogen synthesis rate was increased. Benzylamine appeared thereforeto directly facilitate glucose utilisation in peripheral tissues. When given chronicallyat 2000 or 4000 ìmol/kg/d in drinking water, benzylamine elicited a slightreduction of water consumption but did not change body weight or adiposity anddid not modify oxidative stress markers. Benzylamine treatment improved glucosa tolerance but failed to normalize the elevated glucose fasting plasma levels of VHFDmice. There was no influence of benzylamine ingestion on lipolytic activity, basal andinsulin-stimulated glucose uptake, and on inflammatory adipokine expression inadipocytes. The improvement of glucose tolerance and the lack of adverse effects onadipocyte metabolism, reported here in VHFD mice allow to consider orally givenbenzylamine as a potential antidiabetic strategy which deserves to be further studied in other diabetic models (AU)

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Influence of acute and chronic administration ofbenzylamine on glucose tolerance in diabetic andobese mice fed on very high-fat diet

The combination of vanadate plus benzylamine has been reported to stimulateglucose transport in rodent adipocytes and to mimic other insulin actions in diversestudies. However, benzylamine alone activates glucose uptake in human fat cells andincreases glucose tolerance in rabbits. The aim of this work was to unravel the benzylamineantihyperglycemic action and to test whether its chronic oral administrationcould restore the defective glucose handling of mice rendered slightly obese anddiabetic by very high-fat diet (VHFD). When VHFD mice were i.p. injected withbenzylamine at 0.7 to 700 ìmol/kg before glucose tolerance test, they exhibitedreduced hyperglycemic response without alteration of insulin secretion. Whole bodyglucose turnover, as assessed by the glucose isotopic dilution technique, wasunchanged in mice perfused with benzylamine (total dose of 75 ìmol/kg). However,their in vivo glycogen synthesis rate was increased. Benzylamine appeared thereforeto directly facilitate glucose utilisation in peripheral tissues. When given chronicallyat 2000 or 4000 ìmol/kg/d in drinking water, benzylamine elicited a slightreduction of water consumption but did not change body weight or adiposity anddid not modify oxidative stress markers. Benzylamine treatment improved glucose tolerance but failed to normalize the elevated glucose fasting plasma levels of VHFDmice. There was no influence of benzylamine ingestion on lipolytic activity, basal andinsulin-stimulated glucose uptake, and on inflammatory adipokine expression inadipocytes. The improvement of glucose tolerance and the lack of adverse effects onadipocyte metabolism, reported here in VHFD mice allow to consider orally givenbenzylamine as a potential antidiabetic strategy which deserves to be further studiedin other diabetic models (AU)

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Quantitative gas chromatographic method for the analysis of cis-9, trans-11 and trans-10, cis-12 isomers of the conjugated linoleic acid in liver.

A quantitative GC method for conjugated linoleic acid (CLA) isomers of physiological significance (cis-9, trans-11 CLA and trans-10, cis-12 CLA) as non-esterified fatty acids (NEFA) or triacylglycerols (TAG) was developed. Furthermore, the effect of the internal standard addition point (sample or fat extract) was studied. Response linearity, recovery and precision assays, detection and quantification limits were determined. Linearity was demonstrated over a range from 0.1 to 10 microg/mL. When CLA isomers were present as NEFA, the recovery significantly decreased (P< or =0.05) from 76% to 27.1% (cis-9, trans-11 CLA) and 28.5% (trans-10, cis-12 CLA) when the standards were added to the fat extract or to the initial tissue, respectively. As an application, liver samples from hamsters fed a diet supplemented with both CLA isomers were analyzed. The CLA isomers in liver samples were detected with reasonable reproducibility.

Adiposity and serum parameters in hamsters fed energy restricted diets supplemented or not with trans-10,cis-12 conjugated linoleic acid.

Numerous studies have demonstrated that conjugated linoleic acid (CLA) modulates body composition, reducing body fat accumulation in various mammalian species. However, very few studies have been carried out to assess the effect of CLA on previously stored body fat. The aim of the present work was to analyse the effectiveness of trans-10,cis-12 CLA in improving alterations produced by high-fat feeding in body fat and serum parameters when it was included in an energy-restricted diet. For this purpose male Syrian Golden hamsters were fed on high-fat diet for 7 weeks in order to increase their body fat content, and a further 25% energy-restricted diet supplemented or not with 0.5% trans-10,cis-12 CLA for 3 weeks. Adipose tissues, liver and gastrocnemious muscles were dissected and weighed. Adipocyte diameter and number were assessed in epididymal adipose tissue. Total cholesterol, triacylglycerols, non-esterified fatty acids and glucose were measured in serum. Three weeks of energy restriction resulted in a reduction in body weight and white adipose tissue size in all anatomical locations, without changes in liver and gastrocnemious muscle weights. Epididymal adipocyte size was reduced, but total adipocyte number remained unchanged. Serum cholesterol, triacylglycerols and glucose were significantly reduced. No differences were observed between the restricted groups (control and CLA supplemented). In conclusion, under our experimental conditions, the addition of trans-10,cis-12 CLA to the diet does not increase the benefits produced by energy restriction.

Influence of acute and chronic administration of benzylamine on glucose tolerance in diabetic and obese mice fed on very high-fat diet.

The combination of vanadate plus benzylamine has been reported to stimulate glucose transport in rodent adipocytes and to mimic other insulin actions in diverse studies. However, benzylamine alone activates glucose uptake in human fat cells and increases glucose tolerance in rabbits. The aim of this work was to unravel the benzylamine antihyperglycemic action and to test whether its chronic oral administration could restore the defective glucose handling of mice rendered slightly obese and diabetic by very high-fat diet (VHFD). When VHFD mice were i.p. injected with benzylamine at 0.7 to 700 micromol/kg before glucose tolerance test, they exhibited reduced hyperglycemic response without alteration of insulin secretion. Whole body glucose turnover, as assessed by the glucose isotopic dilution technique, was unchanged in mice perfused with benzylamine (total dose of 75 micromol/kg). However, their in vivo glycogen synthesis rate was increased. Benzylamine appeared therefore to directly facilitate glucose utilisation in peripheral tissues. When given chronically at 2000 or 4000 micromol/kg/d in drinking water, benzylamine elicited a slight reduction of water consumption but did not change body weight or adiposity and did not modify oxidative stress markers. Benzylamine treatment improved glucose tolerance but failed to normalize the elevated glucose fasting plasma levels of VHFD mice. There was no influence of benzylamine ingestion on lipolytic activity, basal and insulin-stimulated glucose uptake, and on inflammatory adipokine expression in adipocytes. The improvement of glucose tolerance and the lack of adverse effects on adipocyte metabolism, reported here in VHFD mice allow to consider orally given benzylamine as a potential antidiabetic strategy which deserves to be further studied in other diabetic models.

Effects of trans-10, cis-12 conjugated linoleic acid on body fat and serum lipids in young and adult hamsters

The aim of the present work was to determine whether t-10, c-12 conjugated linoleic acid (CLA) feeding was able to reduce body fat accumulation and improve the serum lipid profile in adult hamsters fed an atherogenic diet, in order to compare these effects with those observed in young growing hamsters. Young and adult hamsters were fed semi-purified atherogenic diets supplemented with 0.5% linoleic acid or 0.5% t-10, c-12 CLA for 6 weeks. Body weight and food intake were measured every two days. Adipose tissue from different anatomical locations, liver and gastrocnemious muscle were dissected and weighed. Cholesterol, triacylglycerols, non-esterified fatty acids and proteins were determined spectrophotometrically and water content by gravimetry. In young hamsters, no significant differences were found in food intake, final body weight and gastrocnemious muscle weight. White adipose tissue weights were reduced, liver weight was increased and cholesterol and triacylglycerols in both serum and liver were reduced. In adult hamsters, CLA feeding decreased food intake and adipose tissue weights. No changes were observed in other parameters. The present study demonstrates that age has an influence in hamster responsiveness to t-10, c-12 CLA because, although when this isomer is added to an atherogenic diet it reduces body fat accumulation in both young and adults hamsters, the lessening of the effects on serum lipids brought about by atherogenic feeding is only observed in young animals. Moreover, it is clear that liver is a target for CLA in young but not in adult hamsters (AU)

El objetivo del presente estudio fue determinar si el isómero t-10, c-12 del ácido linoleico conjugado (ALC) era capaz de reducir la acumulación de grasa corporal y de mejorar el perfil lipídico en hámsteres adultos alimentados con una dieta aterogénica, con el fin de compararlos con los observados en hámsteres jóvenes en crecimiento. Los animales se alimentaron con dietas aterogénicas suplementadas con 0,5% de ácido linoleico ó 0,5% de ALC t-10, c-12 durante 6 semanas. Se midió cada dos días la ingesta de alimento y el peso corporal. Se diseccionaron y pesaron tejidos adiposos de diferentes localizaciones anatómicas, el hígado y los dos músculos gastrocnemios. El colesterol, los triglicéridos, los ácidos grasos libres y las proteínas se valoraron espectrofotométricamente ricamente y el agua por gravimetría. En los animales jóvenes no se observaron diferencias significativas en la ingesta, el peso corporal final y el peso de los músculos gastrocnemios. Los pesos de los tejidos adiposos blancos se redujeron, el peso de hígado aumentó y el colesterol y los triglicéridos disminuyeron, tanto en suero como en higado. En hámsteres adultos, el ALC disminuyó la ingesta y los pesos de los tejidos adiposos, pero no se observaron cambios en los demás parámetros. El presente estudio demuestra que la edad influye en la respuesta del hámster al ALC t-10, c-12 porque, aunque al ser anadido a una dieta aterogénica reduce la grasa corporal tanto en animales jóvenes como adultos, la atenuación de los efectos de esta dieta sobre los lípidos séricos sólo se pone de manifiesto en los jóvenes. Además, sólo en estos últimos, el hígado es claramente una diana para el ALC (AU)