Beneficial effects of citrulline malate on skeletal muscle function in endotoxemic rat

One of the main sources of reactive oxygen species (ROS) in skeletal muscle is the mitochondria. Prolonged or very high ROS exposure causes oxidative damage, which can be deleterious to muscle function, and as such, there is growing interest in targeting antioxidants to the mitochondria in an effort to prevent or treat muscle dysfunction and damage associated with disease and injury. Paradoxically, however, ROS also act as important signalling molecules in controlling cellular homeostasis, and therefore caution must be taken when supplementing with antioxidants. It is possible that mitochondria-targeted antioxidants may limit oxidative stress without suppressing ROS from non-mitochondrial sources that might be important for cell signalling. Therefore, in this review, we summarise literature relating to the effect of mitochondria-targeted antioxidants on skeletal muscle function. Overall, mitochondria-targeted antioxidants appear to exert beneficial effects on mitochondrial capacity and function, insulin sensitivity and age-related declines in muscle function. However, it seems that this is dependent on the type of mitochondrial-trageted antioxidant employed, and its specific mechanism of action, rather than simply targeting to the mitochondria.

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Recent Advance on Vitamin D in Athletes

Exercise Science ◽

10.15857/ksep.2021.30.3.278 ◽

2021 ◽

Vol 30 (3) ◽

pp. 278-287

Author(s):

Jinkyung Cho ◽

Soo-Hyun Park ◽

Hong-Sun Song

Keyword(s):

Skeletal Muscle ◽

Vitamin D ◽

Exercise Performance ◽

Muscle Function ◽

Vitamin D Supplementation ◽

Molecular Pathways ◽

Skeletal Muscle Function ◽

Vitamin D Receptors ◽

Beneficial Effects ◽

Myocyte Proliferation

PURPOSE: Vitamin D plays important roles in calcium homeostasis and bone metabolism. Since vitamin D receptors (VDRs) are located in a variety of organs, including skeletal muscle, vitamin D has potentially widespread effects. The purpose of this review was to summarize the current understanding of the effects of vitamin D on muscle function and exercise performance in athletes.METHODS: In this narrative review, we summarized previous studies by searching the literature in the PubMed, Google Scholar, and Science Direct databases.RESULTS: Vitamin D has been shown to regulate multiple actions in skeletal muscle tissue, such as myocyte proliferation and growth via genomic and non-genomic molecular pathways. Higher levels of vitamin D are associated with improved skeletal muscle function and exercise performance. Moreover, in some studies, vitamin D supplementation has beneficial effects on muscle strength in athletes, especially those who are vitamin D-deficient.CONCLUSIONS: Vitamin D appears to have beneficial effects on muscle and exercise performance in athletes. However, more studies are needed to clarify the action and dosage of vitamin D in athletes.

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Faculty Opinions recommendation of TNF-alpha-mediated reduction in PGC-1alpha may impair skeletal muscle function after cigarette smoke exposure.

Faculty Opinions – Post-Publication Peer Review of the Biomedical Literature ◽

10.3410/f.1556023.1047131 ◽

2010 ◽

Author(s):

Annemie Schols ◽

Harry Gosker

Keyword(s):

Skeletal Muscle ◽

Cigarette Smoke ◽

Muscle Function ◽

Smoke Exposure ◽

Tnf Alpha ◽

Cigarette Smoke Exposure ◽

Skeletal Muscle Function ◽

Mediated Reduction

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Gait disturbances and muscle dysfunction in fibroblast growth factor 2 knockout mice

Scientific Reports ◽

10.1038/s41598-021-90565-0 ◽

2021 ◽

Vol 11 (1) ◽

Author(s):

C. Homer-Bouthiette ◽

L. Xiao ◽

Marja M. Hurley

Keyword(s):

Skeletal Muscle ◽

Growth Factor ◽

Muscle Strength ◽

Fibroblast Growth Factor ◽

Muscle Function ◽

Fibroblast Growth Factor 2 ◽

Fibroblast Growth ◽

Skeletal Muscle Function ◽

Age Related ◽

Gait Disturbances

AbstractFibroblast growth factor 2 (FGF2) is important in musculoskeletal homeostasis, therefore the impact of reduction or Fgf2 knockout on skeletal muscle function and phenotype was determined. Gait analysis as well as muscle strength testing in young and old WT and Fgf2KO demonstrated age-related gait disturbances and reduction in muscle strength that were exacerbated in the KO condition. Fgf2 mRNA and protein were significantly decreased in skeletal muscle of old WT compared with young WT. Muscle fiber cross-sectional area was significantly reduced with increased fibrosis and inflammatory infiltrates in old WT and Fgf2KO vs. young WT. Inflammatory cells were further significantly increased in old Fgf2KO compared with old WT. Lipid-related genes and intramuscular fat was increased in old WT and old Fgf2KO with a further increase in fibro-adipocytes in old Fgf2KO compared with old WT. Impaired FGF signaling including Increased β-Klotho, Fgf21 mRNA, FGF21 protein, phosphorylated FGF receptors 1 and 3, was observed in old WT and old Fgf2KO. MAPK/ ERK1/2 was significantly increased in young and old Fgf2KO. We conclude that Fgf2KO, age-related decreased FGF2 in WT mice, and increased FGF21 in the setting of impaired Fgf2 expression likely contribute to impaired skeletal muscle function and sarcopenia in mice.

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Fourteen days of smoking cessation improves muscle fatigue resistance and reverses markers of systemic inflammation

Scientific Reports ◽

10.1038/s41598-021-91510-x ◽

2021 ◽

Vol 11 (1) ◽

Author(s):

Mohammad Z. Darabseh ◽

Thomas M. Maden-Wilkinson ◽

George Welbourne ◽

Rob C. I. Wüst ◽

Nessar Ahmed ◽

...

Keyword(s):

Oxidative Stress ◽

Skeletal Muscle ◽

Smoking Cessation ◽

Muscle Fatigue ◽

Fatigue Resistance ◽

Systemic Inflammation ◽

Muscle Function ◽

Low Grade ◽

Skeletal Muscle Function ◽

Tnf Α

AbstractCigarette smoking has a negative effect on respiratory and skeletal muscle function and is a risk factor for various chronic diseases. To assess the effects of 14 days of smoking cessation on respiratory and skeletal muscle function, markers of inflammation and oxidative stress in humans. Spirometry, skeletal muscle function, circulating carboxyhaemoglobin levels, advanced glycation end products (AGEs), markers of oxidative stress and serum cytokines were measured in 38 non-smokers, and in 48 cigarette smokers at baseline and after 14 days of smoking cessation. Peak expiratory flow (p = 0.004) and forced expiratory volume in 1 s/forced vital capacity (p = 0.037) were lower in smokers compared to non-smokers but did not change significantly after smoking cessation. Smoking cessation increased skeletal muscle fatigue resistance (p < 0.001). Haemoglobin content, haematocrit, carboxyhaemoglobin, total AGEs, malondialdehyde, TNF-α, IL-2, IL-4, IL-6 and IL-10 (p < 0.05) levels were higher, and total antioxidant status (TAS), IL-12p70 and eosinophil numbers were lower (p < 0.05) in smokers. IL-4, IL-6, IL-10 and IL-12p70 had returned towards levels seen in non-smokers after 14 days smoking cessation (p < 0.05), and IL-2 and TNF-α showed a similar pattern but had not yet fully returned to levels seen in non-smokers. Haemoglobin, haematocrit, eosinophil count, AGEs, MDA and TAS did not significantly change with smoking cessation. Two weeks of smoking cessation was accompanied with an improved muscle fatigue resistance and a reduction in low-grade systemic inflammation in smokers.

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