Dietary soy protein improves adipose tissue dysfunction by modulating parameters related with oxidative stress in dyslipidemic insulin-resistant rats.

The present study investigates the benefits of the dietary intake of soy protein on adipose tissue dysfunction in a rat model that mimics several aspects of the human metabolic syndrome. Wistar rats were fed a sucrose-rich diet (SRD) for 4 months. After that, half of the animals continued with SRD until month 8 while in the other half, casein protein was replaced by isolated soy protein for 4 months (SRD-S). A reference group consumed a control diet all the time. In adipose tissue we determined: i) the activities of antioxidant enzymes, gene expression of Mn-superoxide dismutase (SOD) and glutathione peroxidase (GPx), and glutathione redox state ii) the activity of xanthine oxidase (XO), ROS levels and the gene expression of NAD(P)H oxidase iii) the expression of the nuclear factor erythroid-2 related factor-2 (Nrf2). Besides, adiposity visceral index, insulin sensitivity, and tumor necrosis factor-α (TNF-α) in plasma were determined. Compared with the SRD-fed rats, the animals fed a SRD-S showed: activity normalization of SOD and glutathione reductase, improvement of mRNA SOD and normalization of mRNA GPx without changes in the expression of the Nrf2, and improvement of glutathione redox state. These results were accompanied by a normalization of XO activity and improvement of both the ROS production as well as TNF-α levels in plasma. Besides, adipocyte size distribution, adiposity visceral index and insulin sensitivity improved. The results suggest that soy protein can be a complementary nutrient for treating some signs of the metabolic syndrome.

Refeeding with conjugated linoleic acid increases serum cholesterol and modifies the fatty acid profile after 48 hours of fasting in rats / Realimentación con ácido linoleico conjugado aumenta colesterol sérico y altera el perfil de ácidos grasos después de 48 horas de ayuno en ratas

There is no consensus about the effects of conjugated linoleic acid (CLA) on lipid metabolism, especially in animals fed a high-fat diet. Therefore, the objective of the present study was to evaluate the incorporation of CLA isomers into serum, liver and adipose tissue, as well as the oxidative stress generated in rats refed with high-fat diets after a 48 hour fast. Rats were refed with diets containing soybean oil, rich in linoleic acid [7% (Control Group - C) or 20% (LA Group)], CLA [CLA Group - 20% CLA mixture (39.32 mole% c9,t11-CLA and 40.59 mole% t10,c12- CLA)], soybean oil + CLA (LA+CLA Group - 15.4% soybean oil and 4.6% CLA) or animal fat (AF, 20% lard). The CLA group showed lower weight gain and liver weight after refeeding, as well as increased serum cholesterol. The high dietary fat intake induced fat accumulation and an increase in α-tocopherol in the liver, which were not observed in the CLA group. Circulating α-tocopherol was increased in the CLA and CLA+LA groups. The high-fat diets reduced liver catalase activity. CLA isomers were incorporated into serum and tissues. In this short term refeeding experimental model, CLA prevented hepatic fat accumulation, although it produced an increase in serum cholesterol (AU)

No hay consenso acerca de los efectos del ácido linoleico conjugado (CLA) sobre el metabolismo lipídico, especialmente en animales alimentados con una dieta alta en grasa. Por lo tanto, el objetivo del presente estudio fue evaluar la incorporación de isómeros de CLA en el suero, hígado y tejido adiposo, así como el estrés oxidativo generado en ratas realimentadas con dietas altas en grasa después de 48 horas de ayuno. Los animales fueron realimentados con dietas que contenían aceite de soja, rico en ácido linoleico [7% (Groupo Control - C)], o 20% (Groupo LA)], CLA [Groupo CLA - 20% de mezclade CLA (39,32% moles del c9,t11-CLA y 40.59% moles del t10,c12-CLA)], aceite de soja + CLA (Grupo LA+- CLA - 15.4 % de aceite de soja y 4,6% de CLA) o grasa animal (Grupo AF, 20% de manteca de cerdo). El grupo CLA tuvo menor aumento de peso y menor peso hepático después de la realimentación, así como aumento del colesterol total em el suero. La dieta alta en grasa indujo la acumulación de grasa y un aumento de α-tocoferol en el hígado, que no se observaron en el grupo CLA. El α-tocoferol sérico fue mayor en los grupos CLA y LA+CLA. Las dietas altas en grasa redujeron la actividad de la catalasa hepática. Isómeros de CLA fueron incorporados em el suero y tejidos. En este modelo de realimentación de corto plazo, el CLA ha impedido la acumulación de grasa hepática, aunque genero un aumento del colesterol total sérico (AU)

Refeeding with conjugated linoleic acid increases serum cholesterol and modifies the fatty acid profile after 48 hours of fasting in rats.

There is no consensus about the effects of conjugated linoleic acid (CLA) on lipid metabolism, especially in animals fed a high-fat diet. Therefore, the objective of the present study was to evaluate the incorporation of CLA isomers into serum, liver and adipose tissue, as well as the oxidative stress generated in rats refed with high-fat diets after a 48 hour fast. Rats were refed with diets containing soybean oil, rich in linoleic acid [7% (Control Group - C) or 20% (LA Group)], CLA [CLA Group - 20% CLA mixture (39.32 mole% c9,t11-CLA and 40.59 mole% t10,c12- CLA)], soybean oil + CLA (LA+CLA Group - 15.4% soybean oil and 4.6% CLA) or animal fat (AF, 20% lard). The CLA group showed lower weight gain and liver weight after refeeding, as well as increased serum cholesterol. The high dietary fat intake induced fat accumulation and an increase in -tocopherol in the liver, which were not observed in the CLA group. Circulating -tocopherol was increased in the CLA and CLA+LA groups. The high- fat diets reduced liver catalase activity. CLA isomers were incorporated into serum and tissues. In this shortterm refeeding experimental model, CLA prevented hepatic fat accumulation, although it produced an increase in serum cholesterol.

No hay consenso acerca de los efectos del ácido linoleico conjugado (CLA) sobre el metabolismo lipídico, especialmente en animales alimentados con una dieta alta en grasa. Por lo tanto, el objetivo del presente estudio fue evaluar la incorporación de isómeros de CLA en el suero, hígado y tejido adiposo, así como el estrés oxidativo generado en ratas realimentadas con dietas altas en grasa después de 48 horas de ayuno. Los animales fueron realimentados con dietas que contenían aceite de soja, rico en ácido linoleico [7% (Groupo Control - C)], o 20% (Groupo LA)], CLA [Groupo CLA - 20% de mezcla de CLA (39,32% moles del c9,t11-CLA y 40.59% moles del t10,c12-CLA)], aceite de soja + CLA (Grupo LA+- CLA - 15.4 % de aceite de soja y 4,6% de CLA) o grasa animal (Grupo AF, 20% de manteca de cerdo). El grupo CLA tuvo menor aumento de peso y menor peso hepático después de la realimentación, así como aumento del colesterol total em el suero. La dieta alta en grasa indujo la acumulación de grasa y un aumento de -tocoferol en el hígado, que no se observaron en el grupo CLA. El -tocoferol serico fue mayor en los grupos CLA y LA+CLA. Las dietas altas en grasa redujeron la actividad de la catalasa hepática. Isómeros de CLA fueron incorporados em el suero y tejidos. En este modelo de realimentación de corto prlazo, el CLA ha impedido la acumulación de grasa hepática, aunque genero un aumento del colesterol total sérico.

Conjugated linoleic acid reduces hepatic steatosis and restores liver triacylglycerol secretion and the fatty acid profile during protein repletion in rats.

Protein depletion is associated with hepatic steatosis and decreased circulating triacylglycerol (TAG). Since conjugated linoleic acid (CLA) increases lean body mass, protects against muscle catabolism, and modulates lipid metabolism, the aim of this work was to investigate the effects of CLA with two different amounts of dietary fat on the regulation of plasma and hepatic TAG concentration, and its possible connections with changes in fatty acid (FA) profile in plasma, liver and adipose tissue and hepatic oxidative status during protein repletion. Rats were fed a low protein diet (14 days) and then a protein repletion diet (30 days), supplemented or not with CLA, containing 7% (w/w) or 20% (w/w) of fat. Hepatic TAG secretion and removal by muscle and adipose tissue lipoprotein lipase, FA profile and liver oxidative status were evaluated. Protein depletion affected hepatic TAG secretion and peripheral removal, decreasing plasma and increasing liver TAG concentration, whereas protein repletion with CLA improved these abnormalities independently of the amount of dietary fat by increasing hepatic TAG secretion. This prevention in the absence of CLA was not observed. CLA was incorporated in plasma and tissues (adipose > liver > plasma, and c9,t11-CLA > t10,c12-CLA), accompanied by alterations in FA composition, mainly in adipose tissue. The hepatic oxidative stress was overcome by protein repletion. CLA had a beneficial impact on TAG metabolism in protein repleted animals, preventing hepatic steatosis through higher hepatic TAG secretion.