scholarly journals PO-231 Effects of exercise on muscle atrophy in simulated weightless rats

2018 ◽  
Vol 1 (5) ◽  
Author(s):  
Zhifei Ke
Keyword(s):  
Skeletal Muscle ◽  
Resistance Exercise ◽  
Muscle Atrophy ◽  
Exercise Intervention ◽  
Muscle Protein ◽  
The Body ◽  
Tail Suspension ◽  
Simulated Weightlessness ◽  
Cross Sectional ◽  
Exercise Muscle

Objective Insufficient physical activity, aerospace weight loss, and fixed treatment of fractures, tendons, and neuropathy, or the resulting muscle atrophy caused by reduced exercise, have become an urgent health problem. Exercise has received widespread attention as an effective means of preventing muscle atrophy. Through the literatures related to "sports and muscle atrophy" at home and abroad, the effects of exercise on muscle atrophy in simulated weightless rats were analyzed, in order to provide theoretical basis and guidance for exercise prevention and treatment of muscle atrophy. Methods The electronic databases PubMed, EMBASE and SPORTDiscus were searched for relevant studies reporting on the effects of physical exercise on muscle therapy. The keywords are: “aerobic exercise or resistance exercise”; "muscle atrophy"; "weightless or weightlessness"and the limitation period is 2013-2018. At the same time, the relevant literatures of the Chinese Journal Full-text Database were searched. The search terms were:“aerobic exercise; resistance exercise; muscle atrophy”, and the language of the article was limited to Chinese. Inclusion criteria: exercise and sarcopenia; effects of exercise on muscle atrophy; relationship between muscle atrophy and exercise. Exclusion criteria: repetitive studies. A total of 54 literature reviews were included in the literature. Results (1)The simulated weightless model is mainly for unloading and tail suspension. After the tail suspension, the soleus muscle becomes thinner and thinner, the elasticity decreases, the volume and mass decrease, the cross-sectional area of the muscle fiber decreases, and the cross-sectional area of the muscle fiber increases after exercise intervention. , suggesting that exercise can effectively slow down the quality of the soleus muscle caused by simulated weightlessness. (2)After 4 weeks of tail suspension, IGF-1 was found to change significantly. Exercise can stimulate the secretion of IGF-1, TESTO and myogenin to some extent, and promote the synthesis of muscle protein. At the same time, myogenin showed different expression under different exercise forms, suggesting myogenin. It may not be used as a predictor of muscle atrophy change. (3) Oxidative stress occurs after 4 weeks of tail suspension, aggravating muscle atrophy, and activity of SOD and GSH-Px is enhanced after exercise intervention. The possible mechanism is to exercise the body SOD and GSH-Px. Vitality, thereby reducing muscle atrophy caused by oxidative stress in the body. (4)Exercise to reduce muscle atrophy may be through down-regulation of atrogin-1 expression and reduction of Caspase-3 expression.  (5) Regardless of endurance exercise or resistance exercise, long-term low-intensity exercise or high-intensity exercise can down-regulate atrogin-1 expression in skeletal muscle. However, different exercise intensity and different exercise patterns have irregular expression of atrogin-1. The effects of different exercise patterns and exercise intensity on the expression of atrogin-1 under simulated weightlessness and its specific mechanism need to be further explored. Conclusions Exercise improves muscle atrophy by promoting the secretion of anabolic hormones in the body, increasing the antioxidant capacity in the body and inhibiting the expression of atrogin-1 protein in the ubiquitin proteasome pathway, which promotes the synthesis and inhibition of skeletal muscle protein to a certain extent. Decomposition of skeletal muscle proteins to reduce muscle atrophy caused by tail suspension.   

scholarly journals Effects of long-term intradialytic oral nutrition and exercise on muscle protein homeostasis and markers of mitochondrial content in patients on hemodialysis

2020 ◽  
Vol 319 (5) ◽  
pp. F885-F894
Author(s):  
Jorge L. Gamboa ◽  
Serpil Muge Deger ◽  
Bradley W. Perkins ◽  
Cindy Mambungu ◽  
Feng Sha ◽  
...  
Keyword(s):  
Skeletal Muscle ◽  
Resistance Exercise ◽  
Muscle Protein ◽  
Nutritional Supplementation ◽  
Sectional Area ◽  
Mitochondrial Content ◽  
Protein Energy Wasting ◽  
Cross Sectional ◽  
Protein Energy

Patients with end-stage kidney disease on maintenance hemodialysis commonly develop protein-energy wasting, a syndrome characterized by nutritional and metabolic abnormalities. Nutritional supplementation and exercise are recommended to prevent protein-energy wasting. In a 6-mo prospective randomized, open-label, clinical trial, we reported that the combination of resistance exercise and nutritional supplementation does not have an additive effect on lean body mass measured by dual-energy X-ray absorptiometry. To provide more mechanistic data, we performed a secondary analysis where we hypothesized that the combination of nutritional supplementation and resistance exercise would have additive effects on muscle protein accretion by stable isotope protein kinetic experiments, muscle mass by MRI, and mitochondrial content markers in muscle. We found that 6 mo of nutritional supplementation during hemodialysis increased muscle protein net balance [baseline: 2.5 (−17.8, 13.0) µg·100 mL−1·min−1 vs. 6 mo: 43.7 (13.0, 98.5) µg·100 mL−1·min−1, median (interquartile range), P = 0.04] and mid-thigh fat area [baseline: 162.3 (104.7, 226.6) cm2 vs. 6 mo: 181.9 (126.3, 279.2) cm2, median (interquartile range), P = 0.04]. Three months of nutritional supplementation also increased markers of mitochondrial content in muscle. Although the study is underpowered to detected differences, the combination of nutritional supplementation and exercise failed to show further benefit in protein accretion or muscle cross-sectional area. We conclude that long-term nutritional supplementation increases the skeletal muscle anabolic effect, the fat cross-sectional area of the thigh, and markers of mitochondrial content in skeletal muscle.

Dynamics of autophagy and ubiquitin proteasome system coordination and interplay in skeletal muscle atrophy

2021 ◽  
Vol 14 ◽  
Author(s):  
Ajay Singh ◽  
Aarti Yadav ◽  
Jatin Phogat ◽  
Rajesh Dabur
Keyword(s):  
Skeletal Muscle ◽  
Muscle Atrophy ◽  
Muscle Protein ◽  
Ubiquitin Proteasome System ◽  
The Body ◽  
Skeletal Muscle Atrophy ◽  
Protein Pool ◽  
Ubiquitin Proteasome ◽  
Muscle Protein Degradation ◽  
Loss Of Mass

: Skeletal muscles are considered the largest reservoirs of the protein pool in the body and are critical for the maintenances of body homeostasis. Skeletal muscle atrophy is supported by various physiopathological conditions that lead to loss of muscle mass and contractile capacity of the skeletal muscle. Lysosomal mediated autophagy and ubiquitin-proteasomal system (UPS) concede the major intracellular systems of muscle protein degradation that result in the loss of mass and strength. Both systems recognize ubiquitination as a signal of degradation through different mechanisms, a sign of dynamic interplay between systems. Hence, growing shreds of evidence suggest the interdependency of autophagy and UPS in the progression of skeletal muscle atrophy under various pathological conditions. Therefore, understanding the molecular dynamics as well associated factors responsible for their interdependency is a necessity for the new therapeutic insights to counteract the muscle loss. Based on current literature, the present review summarizes the factors interplay in between the autophagy and UPS in favor of enhanced proteolysis of skeletal muscle and how they affect the anabolic signaling pathways under various conditions of skeletal muscle atrophy.

scholarly journals Resistance exercise with anti-inflammatory foods attenuates skeletal muscle atrophy induced by chronic inflammation

2020 ◽  
Vol 128 (1) ◽  
pp. 197-211 ◽  
Author(s):  
Koichiro Sumi ◽  
Kinya Ashida ◽  
Koichi Nakazato
Keyword(s):  
Skeletal Muscle ◽  
Resistance Exercise ◽  
Chronic Inflammation ◽  
Muscle Atrophy ◽  
Inflammatory Responses ◽  
Muscle Protein ◽  
Dietary Supplementation ◽  
Skeletal Muscle Atrophy ◽  
Forkhead Box ◽  
Anti Inflammatory

Chronic inflammation (CI) can contribute to muscle atrophy and sarcopenia. Resistance exercise (RE) promotes increased and/or maintenance of skeletal muscle mass, but the effects of RE in the presence of CI are unclear. In this study, we developed a novel animal model of CI-induced muscle atrophy and examined the effect of acute or chronic RE by electrical stimulation. CI was induced in young female Lewis rats by injection with peptidoglycan-polysaccharide (PG-PS). Extracellular signal-regulated kinase (ERK), p70S6 kinase (p70S6K), 4E binding protein 1 (4E-BP1), Akt, and Forkhead box O1 (FOXO1) phosphorylation levels increased in gastrocnemius (Gas) muscle from normal rats subjected to acute RE. After acute RE in CI rats, increased levels of phosphorylated ERK, p70S6K, and 4E-BP1, but not Akt or FOXO1, were observed. Chronic RE significantly increased the Gas weight in the exercised limb relative to the nontrained opposing limb in CI rats. Dietary supplementation with anti-inflammatory agents, eicosapentaenoic/docosahexaenoic acid and α-lactalbumin attenuated CI-induced muscle atrophy in the untrained Gas and could promote RE-induced inhibition of atrophy in the trained Gas. In the trained leg, significant negative correlations ( r ≤ −0.80) were seen between Gas weights and CI indices, including proinflammatory cytokines and white blood cell count. These results indicated that the anabolic effects of RE are effective for preventing CI-induced muscle atrophy but are partially attenuated by inflammatory molecules. The findings also suggested that anti-inflammatory treatment together with RE is an effective intervention for muscle atrophy induced by CI. Taken together, we conclude that systemic inflammation levels are associated with skeletal muscle protein metabolism and plasticity. NEW & NOTEWORTHY This study developed a novel chronic inflammation (CI) model rat demonstrating that resistance exercise (RE) induced activation of protein synthesis signaling pathways and mitigated skeletal muscle atrophy. These anabolic effects were partially abrogated likely through attenuation of Akt/Forkhead box O1 axis activity. The degree of skeletal muscle atrophy was related to inflammatory responses. Dietary supplementation with anti-inflammatory agents could enhance the anabolic effect of RE. Our findings provide insight for development of countermeasures for CI-related muscle atrophy, especially secondary sarcopenia.

scholarly journals Expression of growth-related genes in young and older human skeletal muscle following an acute stimulation of protein synthesis

2009 ◽  
Vol 106 (4) ◽  
pp. 1403-1411 ◽  
Author(s):  
Micah J. Drummond ◽  
Mitsunori Miyazaki ◽  
Hans C. Dreyer ◽  
Bart Pennings ◽  
Shaheen Dhanani ◽  
...  
Keyword(s):  
Skeletal Muscle ◽  
Protein Synthesis ◽  
Resistance Exercise ◽  
Human Skeletal Muscle ◽  
Muscle Protein ◽  
Muscle Protein Synthesis ◽  
Muscle Growth ◽  
Age Groups ◽  
Essential Amino Acids ◽  
Exercise Muscle

Muscle growth is associated with an activation of the mTOR signaling pathway and satellite cell regulators. The purpose of this study was to determine whether 17 selected genes associated with mTOR/muscle protein synthesis and the satellite cells/myogenic program are differentially expressed in young and older human skeletal muscle at rest and in response to a potent anabolic stimulus [resistance exercise + essential amino acid ingestion (RE+EAA)]. Twelve male subjects (6 young, 6 old) completed a bout of heavy resistance exercise. Muscle biopsies were obtained before and at 3 and 6 h post RE+EAA. Subjects ingested leucine-enriched essential amino acids at 1 h postexercise. mRNA expression was determined using qRT-PCR. At rest, hVps34 mRNA was elevated in the older subjects ( P < 0.05) while there was a tendency for levels of myoD, myogenin, and TSC2 mRNA to be higher than young. The anabolic stimulus (RE+EAA) altered mRNAs associated with mTOR regulation. Notably, REDD2 decreased in both age groups ( P < 0.05) but the expression of Rheb mRNA increased only in the young. Finally, cMyc mRNA was elevated ( P < 0.05) in both young and old at 6 h post RE+EAA. Furthermore, RE+EAA also increased expression of several mRNAs associated with satellite function in the young ( P < 0.05), while expression of these mRNAs did not change in the old. We conclude that several anabolic genes in muscle are more responsive in young men post RE+EAA. Our data provide new insights into the regulation of genes important for transcription and translation in young and old human skeletal muscle post RE+EAA.

scholarly journals Investigation of niclosamide as a repurposing agent for skeletal muscle atrophy

PLoS ONE ◽  
2021 ◽  
Vol 16 (5) ◽  
pp. e0252135
Author(s):  
Hyun-Jun Kim ◽  
Ji-Hyung Lee ◽  
Seon-Wook Kim ◽  
Sang-Hoon Lee ◽  
Da-Woon Jung ◽  
...  
Keyword(s):  
Skeletal Muscle ◽  
Muscle Atrophy ◽  
Cancer Cachexia ◽  
Cancer Metastasis ◽  
Muscle Protein ◽  
Muscle Protein Synthesis ◽  
Skeletal Muscle Atrophy ◽  
Differentiation Markers ◽  
Cross Sectional

Skeletal muscle atrophy is a feature of aging (termed sarcopenia) and various diseases, such as cancer and kidney failure. Effective drug treatment options for muscle atrophy are lacking. The tapeworm medication, niclosamide is being assessed for repurposing to treat numerous diseases, including end-stage cancer metastasis and hepatic steatosis. In this study, we investigated the potential of niclosamide as a repurposing drug for muscle atrophy. In a myotube atrophy model using the glucocorticoid, dexamethasone, niclosamide did not prevent the reduction in myotube diameter or the decreased expression of phosphorylated FOXO3a, which upregulates the ubiquitin-proteasome pathway of muscle catabolism. Treatment of normal myotubes with niclosamide did not activate mTOR, a major regulator of muscle protein synthesis, and increased the expression of atrogin-1, which is induced in catabolic states. Niclosamide treatment also inhibited myogenesis in muscle precursor cells, enhanced the expression of myoblast markers Pax7 and Myf5, and downregulated the expression of differentiation markers MyoD, MyoG and Myh2. In an animal model of muscle atrophy, niclosamide did not improve muscle mass, grip strength or muscle fiber cross-sectional area. Muscle atrophy is also feature of cancer cachexia. IC50 analyses indicated that niclosamide was more cytotoxic for myoblasts than cancer cells. In addition, niclosamide did not suppress the induction of iNOS, a key mediator of atrophy, in an in vitro model of cancer cachexia and did not rescue myotube diameter. Overall, these results suggest that niclosamide may not be a suitable repurposing drug for glucocorticoid-induced skeletal muscle atrophy or cancer cachexia. Nevertheless, niclosamide may be employed as a compound to study mechanisms regulating myogenesis and catabolic pathways in skeletal muscle.

scholarly journals Nutritional Strategies to Offset Disuse-Induced Skeletal Muscle Atrophy and Anabolic Resistance in Older Adults: From Whole-Foods to Isolated Ingredients

Nutrients ◽  
2020 ◽  
Vol 12 (5) ◽  
pp. 1533 ◽  
Author(s):  
Ryan N. Marshall ◽  
Benoit Smeuninx ◽  
Paul T. Morgan ◽  
Leigh Breen
Keyword(s):  
Older Adults ◽  
Skeletal Muscle ◽  
Resistance Exercise ◽  
Muscle Mass ◽  
Muscle Atrophy ◽  
Muscle Protein ◽  
Skeletal Muscle Atrophy ◽  
Older Individuals ◽  
Anabolic Resistance ◽  
Whole Foods

Preserving skeletal muscle mass and functional capacity is essential for healthy ageing. Transient periods of disuse and/or inactivity in combination with sub-optimal dietary intake have been shown to accelerate the age-related loss of muscle mass and strength, predisposing to disability and metabolic disease. Mechanisms underlying disuse and/or inactivity-related muscle deterioration in the older adults, whilst multifaceted, ultimately manifest in an imbalance between rates of muscle protein synthesis and breakdown, resulting in net muscle loss. To date, the most potent intervention to mitigate disuse-induced muscle deterioration is mechanical loading in the form of resistance exercise. However, the feasibility of older individuals performing resistance exercise during disuse and inactivity has been questioned, particularly as illness and injury may affect adherence and safety, as well as accessibility to appropriate equipment and physical therapists. Therefore, optimising nutritional intake during disuse events, through the introduction of protein-rich whole-foods, isolated proteins and nutrient compounds with purported pro-anabolic and anti-catabolic properties could offset impairments in muscle protein turnover and, ultimately, the degree of muscle atrophy and recovery upon re-ambulation. The current review therefore aims to provide an overview of nutritional countermeasures to disuse atrophy and anabolic resistance in older individuals.

Vitamin B6 Deficiency can Reduce Fuel Storage and Utilization in Physically Trained Rats

2008 ◽  
Vol 78 (2) ◽  
pp. 64-69 ◽  
Author(s):  
Choi ◽  
Cho
Keyword(s):  
Skeletal Muscle ◽  
Fatty Acid ◽  
Muscle Protein ◽  
Plasma Free Fatty Acid ◽  
Vitamin B ◽  
Liver Protein ◽  
Protein Levels ◽  
Before And After ◽  
Fuel Storage ◽  
Exercise Muscle

This study investigated the effect of vitamin B6 deficiency on the utilization and recuperation of stored fuel in physically trained rats. 48 rats were given either vitamin B6-deficient (B6–) diet or control (B6+) diet for 4 weeks and were trained on treadmill for 30 minutes daily. All animals were then subdivided into 3 groups: before-exercise (BE); during-exercise (DE); after-exercise (AE). The DE group was exercised on treadmill for 1 hour just before being sacrificed. Animals in the AE group were allowed to take a rest for 2 hours after being exercised like the DE group. Glucose and free fatty acids were compared in plasma. Glycogen and triglyceride were compared in liver and skeletal muscle. Protein levels were compared in plasma, liver, and skeletal muscle. Compared with the B6+ group, plasma glucose levels of the B6– group were significantly lower before and after exercise. Muscle glycogen levels of the B6– group were significantly lower than those of the B6+ group regardless of exercise. The liver glycogen level of the B6– group was also significantly lower than that of B6+ group during and after exercise. Before exercise, plasma free fatty acid levels were not significantly different between the B6+ and B6– groups, and plasma free fatty acid levels of the B6– group were significantly lower during and after exercise. The muscle triglyceride level of the B6– group was significantly lower than that of the B6+ group before exercise, and there were no differences between B6+ and B6– groups during and after exercise. Liver triglyceride levels were not significantly different between B6+ and B6– groups. Plasma protein levels of the B6– group were lower than those of B6+ before and after exercise. Muscle protein levels of the B6– group were not significantly different from those of the B6+ group. Liver protein levels of the B6– group were significantly lower than that of the B6+ group after exercise. Liver protein levels of both B6+ and B6– groups were not significantly changed, regardless of exercise. Thus, it is suggested that vitamin B6 deficiency may reduce fuel storage and utilization with exercise in physically trained rats.

scholarly journals Physiology of a Microgravity Environment Invited Review: Microgravity and skeletal muscle

2000 ◽  
Vol 89 (2) ◽  
pp. 823-839 ◽  
Author(s):  
Robert H. Fitts ◽  
Danny R. Riley ◽  
Jeffrey J. Widrick
Keyword(s):  
Skeletal Muscle ◽  
Muscle Atrophy ◽  
Thin Filament ◽  
Molecular Mechanisms ◽  
Skeletal Muscle Atrophy ◽  
Microgravity Environment ◽  
Type I ◽  
Fiber Types ◽  
Maximal Velocity ◽  
Cross Sectional

Spaceflight (SF) has been shown to cause skeletal muscle atrophy; a loss in force and power; and, in the first few weeks, a preferential atrophy of extensors over flexors. The atrophy primarily results from a reduced protein synthesis that is likely triggered by the removal of the antigravity load. Contractile proteins are lost out of proportion to other cellular proteins, and the actin thin filament is lost disproportionately to the myosin thick filament. The decline in contractile protein explains the decrease in force per cross-sectional area, whereas the thin-filament loss may explain the observed postflight increase in the maximal velocity of shortening in the type I and IIa fiber types. Importantly, the microgravity-induced decline in peak power is partially offset by the increased fiber velocity. Muscle velocity is further increased by the microgravity-induced expression of fast-type myosin isozymes in slow fibers (hybrid I/II fibers) and by the increased expression of fast type II fiber types. SF increases the susceptibility of skeletal muscle to damage, with the actual damage elicited during postflight reloading. Evidence in rats indicates that SF increases fatigability and reduces the capacity for fat oxidation in skeletal muscles. Future studies will be required to establish the cellular and molecular mechanisms of the SF-induced muscle atrophy and functional loss and to develop effective exercise countermeasures.

scholarly journals Biochemical approaches for nutritional support of skeletal muscle protein metabolism during sepsis

2004 ◽  
Vol 17 (1) ◽  
pp. 77-88 ◽  
Author(s):  
Thomas C. Vary ◽  
Christopher J. Lynch
Keyword(s):  
Skeletal Muscle ◽  
Amino Acids ◽  
Metabolic Response ◽  
Muscle Protein ◽  
The Body ◽  
Integrated Analysis ◽  
Skeletal Muscle Protein ◽  
Catabolic State ◽  
N Metabolism ◽  
Induced Defects

Sepsis initiates a unique series of modifications in the homeostasis of N metabolism and profoundly alters the integration of inter-organ cooperatively in the overall N and energy economy of the host. The net effect of these alterations is an overall N catabolic state, which seriously compromises recovery and is semi-refractory to treatment with current therapies. These alterations lead to a functional redistribution of N (amino acids and proteins) and substrate metabolism among injured tissues and major body organs. The redistribution of amino acids and proteins results in a quantitative reordering of the usual pathways of C and N flow within and among regions of the body with a resultant depletion of the required substrates and cofactors in important organs. The metabolic response to sepsis is a highly integrated, complex series of reactions. To understand the regulation of the response to sepsis, a comprehensive, integrated analysis of the fundamental physiological relationships of key metabolic pathways and mechanisms in sepsis is essential. The catabolism of skeletal muscles, which is manifested by an increase in protein degradation and a decrease in synthesis, persists despite state-of-the-art nutritional care. Much effort has focused on the modulation of the overall amount of nutrients given to septic patients in a hope to improve efficiencies in utilisation and N economies, rather than the support of specific end-organ targets. The present review examines current understanding of the processes affected by sepsis and testable means to circumvent the sepsis-induced defects in protein synthesis in skeletal muscle through increasing provision of amino acids (leucine, glutamine, or arginine) that in turn act as nutrient signals to regulate a number of cellular processes.

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