Obesity leading to hyperlipidaemia and atherosclerosis is recognised to induce morphological and metabolic changes in many tissues. However, hyperlipidaemia can occur in the absence of obesity. The impact of the latter scenario on skeletal muscle and liver is not understood sufficiently. In this regard, we used the Apolipoprotein E-deficient (ApoE(-/-)) mouse model, an established model of hyperlipidaemia and atherosclerosis, that does not become obese when subjected to a high-fat diet, to determine the impact of Western-type diet (WD) and ApoE deficiency on skeletal muscle morphological, metabolic and biochemical properties. To establish the potential of therapeutic targets, we further examined the impact of Nox2 pharmacological inhibition on skeletal muscle redox biology. We found ectopic lipid accumulation in skeletal muscle and the liver, and altered skeletal muscle morphology and intramuscular triacylglycerol fatty acid composition. WD and ApoE deficiency had a detrimental impact in muscle metabolome, followed by perturbed gene expression for fatty acid uptake and oxidation. Importantly, there was enhanced oxidative stress in the skeletal muscle and development of liver steatosis, inflammation and oxidative protein modifications. Pharmacological inhibition of Nox2 decreased reactive oxygen species production and protein oxidative modifications in the muscle of ApoE(-/-) mice subjected to a Western-type diet. This study provides key evidence to better understand the pathophysiology of skeletal muscle in the context of hyperlipidaemia and atherosclerosis and identifies Nox2 as a potential target for attenuating oxidative stress in skeletal muscle in a mouse model of obesity-independent hyperlipidaemia.

Life expectancy has risen in the past decades, resulting in an increase in the number of aged individuals. Exercise remains one of the most cost-effective treatments against disease and the physical consequences of aging. The purpose of this research was to investigate the effects of aging, long-term and lifelong exercise on the rat urinary metabolome. Thirty-six male Wistar rats were divided into four equal groups: exercise from 3 to 12 months of age (A), lifelong exercise from 3 to 21 months of age (B), no exercise (C), and exercise from 12 to 21 months of age (D). Exercise consisted in swimming for 20 min/day, 5 days/week. Urine samples collection was performed at 3, 12 and 21 months of life and their analysis was conducted by liquid chromatography-mass spectrometry. Multivariate analysis of the metabolite data did not show any discrimination between groups at any of the three aforementioned ages. However, multivariate analysis discriminated the three ages clearly when the groups were treated as one. Univariate analysis showed that training increased the levels of urinary amino acids and possibly protected against sarcopenia, as evidenced by the higher levels of creatine in the exercising groups. Aging was accompanied by decreased levels of urinary amino acids and signs of increased glycolysis. Concluding, both aging and, to a lesser degree, exercise affected the rat urinary metabolome, including metabolites related to energy metabolism, with exercise showing a potential to mitigate the consequences of aging.

Introduction: Apolipoprotein E-deficient mice (ApoE^-/-) develop severe hyperlipidaemia and atherosclerotic lesions throughout the aortic root, features that are aggravated by atherogenic diets. NADPH oxidase 2 (Nox2) is an important enzymatic source of reactive oxygen species that contributes to systemic atherosclerosis in ApoE^-/- mice. The aim of this study was to investigate the role of Nox2 inhibition in skeletal muscle pathophysiology and cellular oxidative stress of ApoE^-/- mice administered a Western-type of diet (WD). Methods: ApoE^-/- mice were maintained on either a chow or a Western diet for 12 weeks and were treated with the Nox2ds-tat inhibitor or control peptide for the last 8 weeks of feeding. Skeletal muscles and the liver were dissected for molecular, biochemical and histological analysis. Results: Individual muscle fibres from ApoE^-/- mice were significantly enlarged due to ectopic fat accumulation. There was an increase in hepatic inflammation and lipid deposition in response to WD administration. Importantly, there was perturbed gene expression for fatty acid metabolism and antioxidant genes, followed by evidence of oxidative stress, as shown by elevated lipid peroxidation and oxidative protein modifications such as carbonylation and tyrosine nitration in the skeletal muscle of WD-fed mice. Pharmacological inhibition of Nox2 decreased superoxide production and protein carbonylation, one of the most harmful protein modifications, in the muscle of ApoE^-/- mice but had no effect on the liver. Conclusions: Our data indicate that ApoE deficiency induces oxidative damage in skeletal muscle and hepatic steatosis that are more profound under Western diet. Nox2 inhibition attenuates oxidative stress in skeletal muscle and holds promise for counteracting the impact of peripheral atherosclerosis in skeletal muscle. This study provides key evidence to better understand the pathophysiology of skeletal muscle in peripheral atherosclerosis and arterial disease; it also identifies alternative therapies to combat muscle oxidative stress.