Arginine and aerobic training prevent endothelial and metabolic alterations in rats at high risk for the development of the metabolic syndrome

Aerobic exercise prevents cardiomyocyte damage caused by oxidative stress in early cardiovascular disease by increasing vascularity while L-arginine supplementation prevents it by increasing activation of the enzyme nitric oxide synthase

L-Arginine and chronic exercise reduce oxidative stress. However, it is unclear how they affect cardiomyocytes during cardiovascular disease (CVD) development. The aim of this research was to investigate the possible effects of L-arginine supplementation and aerobic training on systemic oxidative stress and their consequences on cardiomyocytes during cardiometabolic disease onset caused by excess fructose. Wistar rats were allocated into four groups: control (C), fructose (F, 10% fructose in water), fructose training (FT; moderate running, 50-70% of the maximal velocity), and fructose arginine (FA; 880 mg/kg/day). Fructose was given for two weeks and fructose plus treatments for the subsequent eight weeks. Body composition, blood glucose, insulin, lipid profile, lipid peroxidation, nitrite, metalloproteinase-2 (MMP-2) activity, left ventricle histological changes, microRNA-126, -195, and -146, eNOS, p-eNOS, and TNF-α expressions were analyzed. Higher abdominal fat mass, triacylglycerol level, and insulin level were observed in the F group, and both treatments reversed these alterations. Myocardial vascularization was impaired in fructose-fed groups, except in FT. Cardiomyocyte hypertrophy was observed in all fructose-fed groups. TNF-α levels were higher in fructose-fed groups than in the C group, and p-eNOS levels were higher in the FA than in the C and F groups. Lipid peroxidation was higher in the F group than in the FT and C groups. During CVD onset, moderate aerobic exercise reduced lipid peroxidation, and both training and L-arginine prevented metabolic changes caused by excessive fructose. Myocardial vascularization was impaired by fructose, and cardiomyocyte hypertrophy appeared to be influenced by pro-inflammatory and oxidative environments.

Differential benefits of physical training associated or not with L-arginine supplementation in rats with metabolic syndrome: evaluation of cardiovascular, autonomic and metabolic parameters

Metabolic syndrome (MetS) is characterized by endocrine-metabolic and cardiac alterations that increase the risk of cardiovascular disease, dyslipidemia, and type-2 diabetes mellitus. Dietary supplementation with L-Arginine (L-Arg) is beneficial for fat loss, while chronic aerobic exercise has several benefits in reversing cardiovascular, autonomic, and metabolic dysfunctions caused by obesity. However, the association between these two approaches has not yet been described. This study aimed to evaluate the possible benefits of physical training, with or without L-Arg supplementation, on cardiovascular, autonomic, and metabolic parameters in rats with MetS, which was induced by the subcutaneous administration of monosodium glutamate at 4 mg g^-1day^-1 in rats from the first to fifth day of life. Physical training on a treadmill and supplementation with L-Arg in adulthood were carried out concomitantly for 8 weeks. After this, the animals underwent femoral artery catheterization to record their cardiovascular parameters and autonomic modulation. Organs and blood were removed to measure levels of nitrite, glucose, and hepatic steatosis. In adult rats with MetS, supplementation with L-Arg in combination with physical training reduced hypertension, tachycardia, adipose tissue mass, free fatty acids, and hepatic steatosis. Supplementation with L-Arg and physical training separately was beneficial in reducing several aspects of MetS, but a combination of both was especially effective in reducing adipose tissue and hepatic steatosis. Together, the two therapies can form a good strategy to combat MetS.

Low-Intensity Exercise Affects Cardiac Fatty Acid Oxidation by Increasing the Nuclear Content of PPARα, FOXO1, and Lipin1 in Fructose-Fed Rats

Background and Aim: Excessive fructose consumption along with a sedentary lifestyle provokes metabolic disorders and cardiovascular diseases. Fructose overload causes cardiac insulin resistance and increases reliance on fatty acid (FA) uptake and catabolism. The cardiometabolic benefits of exercise training have long been appreciated. The goal of the presented study is to shed a new light to the preventive role of exercise training on cardiac lipid metabolism in fructose-fed rats. Methods: Male Wistar rats were divided into control (C), sedentary fructose (F), and exercised fructose (EF) groups. Fructose was given as a 10% fructose solution in drinking water for 9 weeks. Low-intensity exercise training was applied for 9 weeks. The protein expression and subcellular localization of Lipin1, peroxisome proliferator-activated receptor α (PPARα), and peroxisome proliferator-activated receptor-γ coactivator 1 α (PGC1) were analyzed in the heart using Western blot. Cardiac forkhead box transcription factor 1 (FOXO1) and sirtuin 1 (SIRT1) protein levels were also evaluated. Gene expression of long-chain acyl-CoA dehydrogenase was analyzed by quantitative polymerase chain reaction. Results: Exercise training has augmented the expression of main regulators of FA oxidation in the heart and achieves its effect by increasing the nuclear content of PPARα, Lipin1, and FOXO1 compared with the fructose group (P = 0.0422, P = 0.000045, P = 0.00958, respectively). In addition, Lipin1, FOXO1, and SIRT1 were increased in nuclear extract after exercise compared with the control group (P = 0.000043, P = 0.0417, P = 0.0329, respectively). In cardiac lysate, low-intensity exercise caused significantly increased protein level of PPARα, PGC1, FOXO1, and SIRT1 compared with control (P = 0.0377, P = 0.0275, P = 0.0096, P = 0.0282, respectively) and PGC1 level compared with the fructose group (P = 0.0417). Conclusion: The obtained results imply that the heart with a metabolic burden additionally relies on FA as an energy substrate after low-intensity running.

Fructose Intake, Hypertension and Cardiometabolic Risk Factors in Children and Adolescents: From Pathophysiology to Clinical Aspects. A Narrative Review

Arterial hypertension, dyslipidemia, alterations in glucose metabolism and fatty liver, either alone or in association, are frequently observed in obese children and may seriously jeopardize their health. For obesity to develop, an excessive intake of energy-bearing macronutrients is required; however, ample evidence suggests that fructose may promote the development of obesity and/or metabolic alterations, independently of its energy intake. Fructose consumption is particularly high among children, because they do not have the perception, and more importantly, neither do their parents, that high fructose intake is potentially dangerous. In fact, while this sugar is erroneously viewed favorably as a natural nutrient, its excessive intake can actually cause adverse cardio-metabolic alterations. Fructose induces the release of pro-inflammatory cytokines, and reduces the production of anti-atherosclerotic cytokines, such as adiponectin. Furthermore, by interacting with hunger and satiety control systems, particularly by inducing leptin resistance, it leads to increased caloric intake. Fructose, directly or through its metabolites, promotes the development of obesity, arterial hypertension, dyslipidemia, glucose intolerance and fatty liver. This review aims to highlight the mechanisms by which the early and excessive consumption of fructose may contribute to the development of a variety of cardiometabolic risk factors in children, thus representing a potential danger to their health. It will also describe the main clinical trials performed in children and adolescents that have evaluated the clinical effects of excessive intake of fructose-containing drinks and food, with particular attention to the effects on blood pressure. Finally, we will discuss the effectiveness of measures that can be taken to reduce the intake of this sugar.

Age and diet modify acute microhemorrhage outcome in the mouse brain

Cerebral microhemorrhages (CMHs) are considered as asymptomatic lesions, but might impair cognition in non-demented elderly individuals. The aging process includes poor vascular health, enhanced at midlife by metabolic disturbances upon high-fat diet (HFD). The onset of CMHs could thus have more serious consequences in midlife subjects with metabolic disturbances. This hypothesis was tested through the induction of multiple CMHs, using cyclodextrin nanoparticles injection, in mice at midlife (14 month old) or at a younger stage (5 month old) after 12 months or 3 months of normal diet or HFD (40% of animal fat) respectively. When induced at 14 months of age, CMHs were not larger but were more numerous (+25%) in mice on HFD compared with mice on normal diet. They slowed down the locomotor activity significantly but caused neither a change in the working memory nor a difference in the visual recognition memory decline. When induced at 5 months of age, CMHs provoked slighter locomotor and cognitive symptoms, regardless the diet. No spontaneous progression of CMHs toward larger hemorrhages was observed after onset when HFD was prolonged up to midlife. Consistently, no precipitated cognitive decline was observed. Middle-age plus time of metabolic disturbances represent enhanced risk factors for CMH outcome.

Arginine supplementation and cardiometabolic risk

PURPOSE OF REVIEW

Because arginine is the substrate for nitric oxide synthesis, which is pivotal to vascular homeostasis and linked to the insulin response, it has long been posited that supplemental arginine could benefit cardiometabolic health.

RECENT FINDINGS

Recent data have supported the view that supplemental arginine could alleviate the initiation and development of endothelial dysfunction and also shown that it may reduce the risk of type 2 diabetes. One important finding is that these effects may indeed vary as a function of the amount of arginine, its form and notably the metabolic status of the population. Some studies have shown that low doses of slow-release arginine are better used for nitric oxide synthesis and beneficial in individuals with abnormal arginine metabolism/bioavailability. Pathophysiological data in rodents have emphasized the importance of arginase activation during the development of cardiometabolic risk, which lends credence to a potential benefit for arginine supplements. Likewise, epidemiological evidence suggests that alterations to arginine bioavailability are important regarding the cardiometabolic risk. However, other metabolic mechanisms linked to the multiple pathways of arginine metabolism may also play a role.

SUMMARY

Further studies are needed to confirm and analyze how and when supplemental arginine is beneficial to cardiometabolic health.

Aerobic Training Associated with Arginine Supplementation Reduces Collagen-Induced Platelet Hyperaggregability in Rats under High Risk to Develop Metabolic Syndrome

BACKGROUND

Increased platelet response is seen in individuals with metabolic syndrome. Previous reports have shown that arginine supplementation and aerobic exercise training enhance vascular nitric oxide (NO) activity and inhibit platelet hyperaggregability; however, the effects of their association remain unknown.

AIM

To investigate whether arginine supplementation and aerobic exercise association may exert beneficial effects, reducing platelet hyperaggregability in rats under high risk to develop metabolic syndrome.

METHODS

Wistar rats were divided into two groups: control (C) and fructose (F - water with 10% of fructose). After two weeks, the F group was subdivided into four groups: F, the same as before; fructose + arginine (FA - 880 mg/kg/day of L-arginine by gavage); fructose + training (FT); and fructose + arginine + training (FTA). Treatment lasted for eight weeks.

RESULTS

The fructose administration was able to increase the collagen-induced platelet aggregation (27.4 ± 2.7%) when compared to the C group (8.0 ± 3.4%). Although the arginine supplementation (32.2 ± 6.3%) or aerobic training (23.8 ± 6.5%) did not promote any change in platelet collagen-induced hyperaggregability, the association of arginine supplementation and aerobic exercise promoted an inhibition of the platelet hyperaggregability induced by fructose administration (13.9 ± 4.4%) (P < 0.05). These effects were not observed when ADP was employed as an agonist. In addition, arginine supplementation associated with aerobic exercise promoted a decrease in interleukin-6 (IL-6) and interleukin-8 (IL-8) serum levels when compared to the fructose group, demonstrating an anti-inflammatory effect.

CONCLUSIONS

Our data indicate an important role of arginine supplementation associated with aerobic exercise, reducing platelet hyperaggregability and inflammatory biomarker levels in rats under high risk to develop metabolic syndrome.

Dietary supplementation with camu-camu and continuous exercises in the treatment of obesity

ABSTRACT Objective The goal of this study were to investigate the effects of continuous exercise with/or without the ingestion the Camu-camu pulp in a rat model of obesity. Methods Neonate male Wistar rats, receiving monosodium glutamate, subcutaneously were separated into foour groups: sedentary group S (no treatment), exercise group E (continuous swimming training), Camu-camu group C (25mL of pulp of Camu-camu/day) and exercise and Camu-camu group EC (25mL of pulp of Camu-camu/day, continuous swimming). After 12 weeks, the animals were received euthanasia. Results The exercise program was conducted for five days for 12 weeks and the effects of supplementation with or without Camu-camu in obese rats were analyzed, showing that the relative levels of the variables cholesterol, triglycerides, glucose, High Density Lipoprotein and Low Density Lipoprotein and in all groups there was a significant reduction (.<0.001), except for the control group. Body weight and feed intake, epididymal and visceral fat deposits were not significantly different between the means of groups C and E, but these groups showed a significant difference when compared to the EC group (.<0.001). Conclusion The results demonstrate the effectiveness of continuous exercise and diet supplemented with Camu-camu fruit pulp to control obesity.