Víctor M. Rodríguez

Effects of different doses of resveratrol on body fat and serum parameters in rats fed a hypercaloric diet

Recently resveratrol, a compound naturally occurring in various plants, has been proposed as a potential anti-obesity compound. The aim of the present work was to analyse the effects of different doses of resveratrol on body fat and serum parameters in rats. Thirty-two male Sprague-Dawley rats were randomly divided into four groups and fed on a hypercaloric diet for 6 weeks. The doses oftrans-resveratrol used were 6, 30 and 60 mg/kg body weight/d in RSV1, RSV2 and RSV3 groups respectively. The stability of resveratrol when added to the diet was evaluated. Blood samples were collected, and white adipose tissue from different anatomical locations, interscapular brown adipose tissue, gastrocnemious muscles and liver were weighed. Commercial kits were used to measure serum cholesterol, glucose, triacylglycerols and non-esterified fatty acids. While the lowest dose did not have a body fat reducing effect, the intermediate dose reduced all the white adipose depots. The highest dose significantly reduced mesenteric and subcutaneous depots but not epididymal and perirenal tissues. Although the reduction in all the anatomical locations analysed was 19% in the RSV3 group, in the RSV2 group it was 24%. No significant differences among the experimental groups were found in brown adipose tissue, gastrocnemious muscle or liver weights. Serum parameters were not affected by resveratrol intake because no differences among the experimental groups were observed. These results suggest that resveratrol is a molecule with potential anti-obesity effect. The most effective of the three experimental doses was 30 mg/kg body weight/d.

Hepatic lipid metabolic pathways modified by resveratrol in rats fed an obesogenic diet.

OBJECTIVE The scientific community is on the look-out for safe biomolecules useful in the prevention of obesity and related aberrations such as fatty liver. This study analyzed the influence of resveratrol on hepatic triacylglycerol metabolism. METHODS Male Sprague-Dawley rats were divided into control and resveratrol-treated groups (30 mg/kg of body weight per day) and fed a commercial obesogenic diet for 6 wk. Liver triacylglycerol content and the activity of carnitine palmitoyl transferase-Ia (CPT-Ia), acyl-coenzyme A oxydase (ACO), fatty acid synthase (FAS), glucose-6-phosphate dehydrogenase (G6PDH), malic enzyme (ME), acetyl-coenzyme A carboxylase (ACC), adenosine monophosphate-activated protein kinase (AMPK), and peroxisome proliferator-activated receptor-γ coactivator-1α (PGC-1α) activation were measured. Mitochondrial protein cytochrome C oxidase subunit 2 (COXII), mitochondrial transcription factor A (TFAM), sterol regulatory element-binding protein-1c (SREBP-1c), peroxisome proliferator-activated receptor-α (PPAR-α), sirtuin-1 (SIRT1), hepatocyte nuclear factor receptor-4α (HNF-4α), and PGC-1α mRNA levels were also analyzed. Serum insulin was quantified. RESULTS Resveratrol decreased liver fat accumulation, increased CPT-Ia and ACO, and decreased ACC activities. Other lipogenic enzymes, FAS, ME, and G6PDH were not modified. The polyphenol activated AMPK and PGC-1α. The expression of SRBP-1c, PPAR-α, SIRT1, PGC-1α, HNF-4α, TFAM, and COXII was not modified. No changes in serum insulin levels were observed. CONCLUSION Resveratrol partly prevents the increase in liver fat accumulation induced by high-fat high-sucrose feeding by increasing fatty acid oxidation and decreasing lipogenesis. These effects are mediated by the activation of the AMPK/SIRT1 axis.

Thermogenesis is involved in the body-fat lowering effects of resveratrol in rats.

The effect of resveratrol on thermogenesis in skeletal muscle and interscapular brown adipose tissue (IBAT) was investigated. Rats were fed an obesogenic diet supplemented with resveratrol (30mg/kg/day) or not supplemented for 6weeks. Resveratrol intake led to increased gene expression of mitochondrial-transcription-factor-A (TFAM), mitochondrial-protein-cytochrome-C-oxidase subunit-2 (COX2), sirtuin-1 (SIRT1), peroxisome-proliferator-activated-receptor-β/δ (PPARβ/δ) and proliferator-activated-receptor-gamma-coactivator1-α (PGC-1α) in IBAT and increased UCP1protein expression; however, peroxisome-proliferator-activated-receptor-α (PPARα) expression remained unchanged. In gastrocnemius muscle, resveratrol increased the gene expression of TFAM and COX2; however, no changes were observed in levels of SIRT1, PGC-1α and PPARβ/δ. Acetylated-PGC-1α was decreased in the resveratrol-treated group, indicating a higher level of activation, and a significant increase of UCP3 protein expression was observed in this group. The increases in UCP protein expression in two important thermogenic tissues after resveratrol treatment may contribute to increased whole-body energy dissipation, which may help to better understand the body-fat lowering effect of this polyphenol.

Effects of conjugated linoleic acid on body fat accumulation and serum lipids in hamsters fed an atherogenic diet.

Conjugated linoleic acid (CLA) refers to a mixture of naturally occurring positional and geometric isomers of linoleic acid that exist in dairy products and meat. The aim of the present work was to study the effects ofc-9,t-11 andt-10,c-12 CLA isomers on body fat accumulation and serum lipids in hamsters fed an atherogenic diet. Hamsters were divided in four groups: one group was fed a chow diet (control) and the other three groups were given semi-purified atherogenic diets with 0.5% linoleic acid (LA),c-9,t-11 ort-10,c-12 CLA. Body weight and food intake were measured daily. After 6 weeks, adipose tissues from different anatomical locations and liver were dissected and weighed. Serum glucose, total cholesterol, HDL-c, LDL-c and triacylglycerol levels, as well as total and free cholesterol, triacylglycerol and phospholipid content in liver were determined by enzymatic methods. No differences in either energy intake or final body weight were found. The addition oft-10,c-12 CLA reduced fat accumulation and led to lower serum cholesterol, as compared with LA group. Nevertheless the level remained higher than in the control animals. The reduction in serum cholesterol was limited to LDL-c. This isomer also reduced triacylglycerol content in liver but did not modify serum triacylglycerol level. In summary, the present study demonstrates thatt-10,c-12 CLA is the biologically active agent when anti-obesity and hypocholesterolaemic properties of CLA are considered. In contrast, the isomerc-9,t-11 has no effect on lipid metabolism in hamsters.ResumenEl término ácido linoleico conjugado (ALC) se utiliza para designar una serie de isómeros del ácido linoleico, presentes en los lácteos y la carne, que presentan los dobles enlaces en posición conjugada. El objetivo del presente trabajo consistió en estudiar el efecto de los isómerosc-9,t-11 yt-10,c-12 del ALC sobre la acumulación de grasa corporal y los lípidos séricos, en hámsters alimentados con una dieta aterogénica. Los hámsters se distribuyeron en cuatro grupos: un grupo recibió pienso de laboratorio (control) y los otros tres grupos, dietas aterogénicas con 0,5% de ácido linoleico, ALCc-9,t-11 ó ALCt-10,c-12. Se midió diariamente la ingesta de alimento y el peso corporal. Tras 6 semanas, se diseccionaron y pesaron los tejidos adiposos de diferentes localizaciones anatómicas y el hígado. Se midieron las concentraciones séricas de glucosa, colesterol total, c-HDL, c-LDL y triglicéridos, y el contenido hepático de colesterol total y libre, triglicéridos y fosfolípidos, por métodos enzimáticos. No se encontraron diferencias significativas ni en la ingesta de energía ni en el peso corporal final. El isómerot-10,c-12 redujo la acumulación de grasa y disminuyó el colesterol total sérico; no obstante, su nivel se mantuvo por encima del de los animales control. La reducción del colesterol sérico se produjo a expensas del c-LDL. Este isómero también disminuyó el contenido hepático de triglicéridos pero no modificó los triglicéridos séricos. El presente estudio demuestra que el isómerot-10,c-12 del ALC es el biológicamente activo como agente anti-obesidad e hipocolesterolemiante. Por el contrario, el isómeroc-9,t-11 no afectó al metabolismo lipídico en hámsters.

Distribution of resveratrol metabolites in liver, adipose tissue, and skeletal muscle in rats fed different doses of this polyphenol.

This study aimed to characterize resveratrol metabolite profiles in liver, skeletal muscle, and adipose tissue in rats treated for 6 weeks with 6, 30, or 60 mg of trans-resveratrol/kg body weight/d. Resveratrol metabolites were quantified by liquid chromatography-tandem mass spectrometry. The greatest number of metabolites was found in liver followed by adipose tissue. A great number of metabolites in muscle was below the limit of detection. The amounts of sulfate conjugates tended to increase when resveratrol dosage was enhanced, while the glucuronide ones increased only between 6 and 30 mg/kg/d. Microbiota metabolites were detected in higher amounts than resveratrol conjugates in liver, while the opposite occurred in adipose tissue and muscle. So, the largest amounts of resveratrol metabolites were found in liver, intermediate amounts in adipose tissue, and the lowest amounts in muscle. Sulfate conjugates, but not glucuronides, showed a dose-response pattern. Microbiota metabolites were predominant in liver.

The trans-10,cis-12 isomer of conjugated linoleic acid reduces hepatic triacylglycerol content without affecting lipogenic enzymes in hamsters

Conjugated linoleic acid (CLA) refers to the positional and geometric dienoic isomers of linoleic acid. The dietary intake of CLA has been associated with changes in lipid metabolism. The aim of the present work was to assess the effects of the two main isomers of CLA on sterol regulatory element binding protein (SREBP)-1a and SREBP-1c mRNA levels, as well as on mRNA levels and the activities of several lipogenic enzymes in liver. For this purpose hamsters were fed an atherogenic diet supplemented with 5 g linoleic acid, cis-9,trans-11 or trans-10,cis-12 CLA/kg diet for 6 weeks. The trans-10,cis-12 isomer intake produced significantly greater liver weight, but also significantly decreased liver fat accumulation. No changes in mRNA levels of SREBP-1a, SREBP-1c and lipogenic enzymes, or in the activities of these enzymes, were observed. There was no effect of feeding cis-9,trans-11 CLA. These results suggest that increased fat accumulation in liver does not occur on the basis of liver enlargement produced by feeding the trans-10,cis-12 isomer of CLA in hamsters. The reduction in hepatic triacylglycerol content induced by this isomer was not attributable to changes in lipogenesis.

trans-10, cis-12 Conjugated linoleic acid inhibits lipoprotein lipase but increases the activity of lipogenic enzymes in adipose tissue from hamsters fed an atherogenic diet

The aim of the present work was to investigate the effects of trans-10,cis-12 conjugated linoleic acid (CLA) on the activity and expression of lipogenic enzymes and lipoprotein lipase (LPL), as well as on the expression of transcriptional factors controlling these enzymes, in adipose tissue from hamsters, and to evaluate the involvement of these changes in the body fat-reducing effect of this CLA isomer. Thirty male hamsters were divided into three groups and fed atherogenic diets supplemented with 0 (linoleic group), 5 or 10 g trans-10,cis-12 CLA/kg diet, for 6 weeks. Body and adipose tissue weights, food intake and serum insulin were measured. Total and heparin-releasable LPL and lipogenic enzyme activities (acetyl-CoA carboxylase (ACC); fatty acid synthase (FAS); glucose-6-phosphate dehydrogenase (G6PDH); and malic enzyme (ME)) were assessed. ACC, FAS, LPL, sterol regulatory element-binding proteins (SREBP-1a), SREBP-1c and PPARgamma mRNA levels were also determined by real-time PCR. CLA did not modify food intake, body weight and serum insulin level. CLA feeding reduced adipose tissue weight, LPL activity and expression, and increased lipogenic enzyme activities, despite a significant reduction in ACC and FAS mRNA levels. The expression of the three transcriptional factors analysed (SREBP-1a, SREBP-1c and PPARgamma) was also reduced. These results appear to provide a framework for partially understanding the reduction in body fat induced by CLA. Inhibition of LPL activity seems to be an important mechanism underlying body fat reduction in hamsters. Further research is needed to better characterize the effects of CLA on lipogenesis and the role of these effects in CLA action.

Differential effects of diets that provide different lipid sources on hepatic lipogenic activities in rats under ad libitum or restricted feeding.

This work was designed to study the effect of different lipid sources on hepatic lipogenic enzyme activity in rats fed ad libitum or energy-controlled diets. Male Wistar rats were fed diets containing 40% of energy as fat (olive oil, sunflower oil, palm oil, or beef tallow) for 4 wk. In experiment 1 rats had free access to food, and in experiment 2 rats were fed a controlled amount of food. In both experiments, rats fed the olive oil diets had higher activities of glucose-6-phosphate dehydrogenase, malic enzyme, fatty acid synthase, and acetyl-CoA carboxylase (P < 0.05) than rats fed the other fats. It is unlikely that this effect could be attributed to the stimulation by insulin or triiodothyronine because serum values did not differ among the groups. Enzymatic activities were positively and significantly correlated with liver triacylglycerol content, but not with serum triacylglycerol levels. No interaction between lipid source and feeding protocol was found. Oleic acid and components in olive oil other than fatty acids, such as phytosterols, may account for the effects of dietary fat on lipogenic enzyme activity.

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 oftrans-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.ResumenEl potencial del ácido linoleico conjugado (CLA) como molécula anti-obesidad para seres humanos sigue siendo una cuestión en debate. Por ello, gran cantidad de trabajos científicos se centra en la investigación de nuevas moléculas eficaces y sin efectos nocivos sobre la salud. El objectivo del presente trabajo fue estudiar, en rata, los efectors 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 séricos y la composición del hígado, y comparar estos efectos con los deltrans-10,cis-12, CLA. Se utilizaron 26 ratas Wistar macho divididas en tres grupos que fueron alimentados durante 7 semanas con dietas hipergrasas, suplementadas o no (grupo control) al 0,5% con eltrans-10,cis-12 CLA (grupo CLA) o al 0,5% con el ácido jacárico (grupo CLNA). No se encontraron diferencias significativas en la ingesta de dieta, ni en el peso corporal final, ni en la composición del hígado. El CLA redujo la masa adiposa, pero no lo hizo el CLNA. Ambos disminuyeron significativamente el colesterol no-HDL. A pesar de la ausencia de cambios significativos en la glucemia e insulinemia, el índice HOMA-IR y los niveles séricos de AGL aumentaron significativamente en las ratas alimentadas con CLNA. En conclusión, en nuestras condiciones experimentales, el ácido jacárico, a diferencia del CLA, no muestra un efecto reductor de la grasa corporal. A pesar de que mejora el perfil de lipoproteínas, altera la función insulínica. Por lo tanto, este CLNA no puede ser propuesto como una molécula antiobesidad.

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.ResumenEl 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.