OBJECTIVE: To assess the impacts of electroacupuncture (EA) on the gait, oxidative stress, inflammatory reaction, and protein degradation in the rats of denervated skeletal muscle atrophy, and explore the potential mechanism of EA for alleviating denervated skeletal muscle atrophy. METHODS: Forty male SD rats, 8 weeks old, were randomly assigned to a sham-surgery group, a model group, an EA group, and a p38 MAPK inhibitor group, with 10 rats in each group. The right sciatic nerve was transected to establish a rat model of denervated skeletal muscle atrophy in the model group, the EA group and the p38 MAPK inhibitor group. In the sham-surgery group, the nerve was exposed without transection. One day after successful modeling, the rats in the EA group received EA at "Huantiao" (GB30) and "Zusanli" (ST36) on the right side, using a continuous wave with a frequency of 2 Hz and current intensity of 1 mA, for 15 min in each session, EA was delivered once a day, 6 times a week. In the p38 MAPK inhibitor group, the rats received the intraperitoneal injection with SB203580 (5 mg/kg), once a day, 6 times a week. The intervention was composed of 3 weeks in each group. After the intervention completion, the CatWalk XT 10.6 animal gait analysis system was used to record the gait parameters of rats. The wet weight ratio of the gastrocnemius muscle was calculated after the sample collected. Using HE staining, the fiber morphology and cross-sectional area of the gastrocnemius muscle were observed; ELISA was employed to measure the content of interleukin (IL)-6, IL-1β, and tumor necrosis factor (TNF)-α in the gastrocnemius muscle; the biochemical hydroxyamine method was adopted to detect the content of superoxide dismutase (SOD) and malondialdehyde (MDA) in the gastrocnemius muscle; with immunohistochemistry and Western blot used, the expression of p38 mitogen-activated protein kinase (p38 MAPK), phosphorylated (p)-p38 MAPK, muscle atrophy F-box gene (Atrogin-1), muscle RING finger 1 (Murf-1), nuclear factor E2-related factor 2 (Nrf2), and heme oxygenase-1 (HO-1) was detected in the gastrocnemius muscle. RESULTS: Compared to the sham-surgery group, in the model group, the standing duration, the swing time and the step cycle were increased (P<0.001), the footprint area of the maximum contact time, the print area, the average intensity of the maximum contact time, the average intensity, the swing speed, and the step length were decreased (P<0.001); the wet weight ratio of gastrocnemius muscle and fiber cross-sectional area were reduced (P<0.001); the content of IL-6, IL-1β, TNF-α and MDA in gastrocnemius muscle elevated (P<0.001), and that of SOD reduced (P<0.001); the positive and protein expression of p-p38 MAPK, Atrogin-1 and Murf-1 elevated (P<0.001) and that of Nrf2 and HO-1 dropped (P<0.001). When compared with the model group, in the EA group and the p38 MAPK inhibitor group, the standing duration, the swing time and the step cycle decreased (P<0.01), the footprint area of the maximum contact time, the print area, the average intensity of the maximum contact time, the average intensity, the swing speed, and the step length increased (P<0.01); the wet weight ratio of gastrocnemius muscle and fiber cross-sectional area were improved (P<0.01, P<0.05); the content of IL-6, IL-1β, TNF-α and MDA in gastrocnemius muscle dropped (P<0.05, P<0.01), and that of SOD elevated (P<0.01, P<0.05); the positive and protein expression of p-p38 MAPK, Atrogin-1 and Murf-1 dropped (P<0.01, P<0.05) and that of Nrf2 and HO-1 increased (P<0.01, P<0.05). CONCLUSION Electroacupuncture may alleviate skeletal muscle atrophy in denervated skeletal muscle atrophy rats by mediating the p38 MAPK activity, thereby suppressing oxidative stress, inflammatory reaction, and protein degradation.
Animals ; Electroacupuncture ; Male ; Rats ; p38 Mitogen-Activated Protein Kinases/genetics* ; Rats, Sprague-Dawley ; Muscular Atrophy/metabolism* ; Muscle, Skeletal/metabolism* ; Humans ; Signal Transduction ; Superoxide Dismutase/genetics* ; Tumor Necrosis Factor-alpha/genetics* ; Oxidative Stress ; MAP Kinase Signaling System ; Acupuncture Points

This study aims to explore the role and mechanism of CXC chemokine receptor 3 (CXCR3) in cisplatin-induced skeletal muscle atrophy. Wild-type mice were divided into two groups: cisplatin group and control group (treated by normal saline). The results showed that, compared to the control group, the expression levels of CXCR3 mRNA and protein were significantly up-regulated in the skeletal muscle of the cisplatin group, suggesting that CXCR3 may play an important role in the model of cisplatin-induced skeletal muscle atrophy. To further investigate its role and potential mechanisms, CXCR3 knockout mice and wild-type mice were treated with cisplatin to induce skeletal muscle atrophy. The results revealed that CXCR3 knockout not only failed to alleviate cisplatin-induced skeletal muscle atrophy, but also further reduced body weight, skeletal muscle mass, and muscle fiber cross-sectional area. Further analysis showed that, in the cisplatin-induced muscle atrophy model, CXCR3 knockout significantly up-regulated the expression levels of E3 ubiquitin ligases in skeletal muscle and down-regulated the expression levels of myogenic regulatory factors. To explore the molecular mechanism by which CXCR3 gene deletion exacerbated cisplatin-induced skeletal muscle atrophy, transcriptomic sequencing was performed on the atrophied skeletal muscles of wild-type and CXCR3 knockout mice. The results showed that, compared to wild-type mice, 14 genes were significantly up-regulated and 12 genes were significantly down-regulated in the skeletal muscle of CXCR3 knockout mice. Gene set enrichment analysis (GSEA) revealed a significant enrichment of genes related to fatty acid β-oxidation. Quantitative real-time PCR validation results were consistent with the transcriptomic sequencing results. These findings suggest that CXCR3 may counteract cisplatin-induced skeletal muscle atrophy by up-regulating E3 ubiquitin ligases, down-regulating myogenic regulatory factors, and enhancing the recruitment of fatty acid β-oxidation-related genes.
Animals ; Cisplatin/adverse effects* ; Muscular Atrophy/physiopathology* ; Mice ; Receptors, CXCR3/metabolism* ; Ubiquitin-Protein Ligases/metabolism* ; Mice, Knockout ; Oxidation-Reduction ; Fatty Acids/metabolism* ; Muscle, Skeletal/metabolism* ; Mice, Inbred C57BL ; Male

The maintenance of skeletal muscle quality involves various signal pathways that interact with each other. Under normal physiological conditions, these intersecting signal pathways regulate and coordinate the hypertrophy and atrophy of skeletal muscles, balancing the protein synthesis and degradation of muscle. When the total rate of protein synthesis exceeds that of protein degradation, the muscle gradually becomes enlarged, while when the total rate of protein synthesis is lower than that of protein degradation, the muscle shrinks. Myocyte atrophy mainly involves two protein degradation pathways, namely ubiquitin-proteasome and autophagy-lysosome. Protein degradation pathway is activated during muscle atrophy, resulting in the loss of muscle mass. Muscle atrophy can occur under various conditions such as malnutrition, aging and cachexia. Skeletal muscle atrophy caused by orthopedic diseases mainly includes disuse muscular atrophy caused by fracture and denervation muscular atrophy. The signal pathways that control and coordinate protein synthesis and degradation in skeletal muscle include insulin-like growth factor 1 (IGF1)-Akt-mammalian target of rapamycin (mTOR), myostatin-activin A-Smad, G protein α inhibitory peptide 2 (Gαi2)-PKC, nuclear factor κB (NF-κB), ectodysplasin A2 receptor (EDA2R)-NF-κB inducing kinase (NIK) and mitogen-activated protein kinase (MAPK) pathways. This paper provides a comprehensive review of the protein degradation pathways in skeletal muscle atrophy and the associated signal pathways regulating protein degradation in muscular atrophy.
Humans ; Muscular Atrophy/etiology* ; Muscle, Skeletal/pathology* ; Signal Transduction ; Animals ; Insulin-Like Growth Factor I/metabolism* ; Myostatin/physiology* ; TOR Serine-Threonine Kinases/metabolism* ; Autophagy/physiology* ; NF-kappa B/metabolism* ; Proteolysis ; Proteasome Endopeptidase Complex/physiology*

OBJECTIVE: To investigate the therapeutic effects of massage on denervated skeletal muscle atrophy in rats and its mechanism. METHODS: Forty-eight male SD rats were randomly divided into model group (n=24) and massage group (n=24). Gastrocnemius muscle atrophy model was established by transecting the right tibial nerve of rat. On the second day after operation, the gastrocnemius muscle of the rats in the massage group was given manual intervention and the model group was not intervened. Six rats were sacrificed at the four time points of 0 d, 7 d, 14 d and 21 d. The gastrocnemius of the rats were obtained and measured the wet mass ratio after weighing. Cross-sectional area and diameter of the muscle fiber were measured after HE staining. The relative expressions of miR-23a, Akt, MuRF1 and MAFbx mRNA were tested with qPCR. RESULTS: Compared with 0 d, the wet weight ratio, cross-sectional area and diameter of gastrocnemius muscle showed a progressive decline in the model group and massage group. The wet weight ratio, cross-sectional area and diameter of gastrocnemius muscle in the massage group were higher than those in the model group on 7 d, 14 d and 21 d (P＜0.05, P＜0.01). Compared with 0 d, the expressions of MuRF1, MAFbx and Akt mRNA were increased first and then were decreased in the model group and massage group. The expression of MuRF1 mRNA in massage group was lower than that in model group on 7 d and 21 d (P＜0.05, P＜0.01). The expression of MAFbx mRNA in massage group was lower than that in model group on 7 d, 14 d and 21 d (P＜0.01, P＜0.05, P＜0.01). The expression of Akt mRNA in massage group was higher than that in model group on 7 d, 14 d and 21 d (P＜0.05, P＜0.01). Compared with 0 d, the expression of miR-23a mRNA was increased in the model group and massage group on 21 d, and the expression of miR-23a mRNA in massage group was higher than that in model group (P＜ 0.05). CONCLUSION Massage can delay the atrophy of denervated skeletal muscle. The mechanism may be related to up-regulation of the expression of miR-23a and Akt mRNA, down-regulation of the expressions of MuRF1 and MAFbx mRNA, inhibition of protein degradation rate, and reduction of skeletal muscle protein degradation.
Animals ; Male ; Massage ; MicroRNAs ; metabolism ; Muscle Fibers, Skeletal ; Muscle Proteins ; metabolism ; Muscle, Skeletal ; physiopathology ; Muscular Atrophy ; therapy ; Proto-Oncogene Proteins c-akt ; metabolism ; Rats ; Rats, Sprague-Dawley ; SKP Cullin F-Box Protein Ligases ; metabolism ; Tripartite Motif Proteins ; metabolism ; Ubiquitin-Protein Ligases ; metabolism

Spinal muscular atrophy with respiratory distress type 1 (SMARD1) is a rare autosomal recessive disorder caused by a defect in the immunoglobulin mu binding protein 2 (IGHMBP2) gene, leading to motor neuron degeneration. We identified an infant with SMARD1 by targeted exome sequencing from a consanguineous Syrian family having a history of recurrent infant deaths. The patient initially presented intrauterine growth retardation, poor sucking, failure to thrive, and respiratory failure at the age of two months, and an inborn error of metabolism was suspected at first. Over a period of one month, the infant showed rapid progression of distal muscular weakness with hand and foot contractures, which were suggestive of neuromuscular disease. Using targeted exome sequencing, the mutation in IGHMBP2 was confirmed, although the first report was normal. Targeted exome sequencing enabled identification of the genetic cause of recurrent mysterious deaths in the consanguineous family. Additionally, it is suggested that a detailed phenotypic description and communication between bioinformaticians and clinicians is important to reduce false negative results in exome sequencing.
Carrier Proteins ; Contracture ; Exome ; Failure to Thrive ; Fetal Growth Retardation ; Foot ; Hand ; Humans ; Immunoglobulins ; Infant Death ; Infant ; Metabolism ; Motor Neurons ; Muscle Weakness ; Muscular Atrophy, Spinal ; Neuromuscular Diseases ; Respiratory Insufficiency

Active Transport, Cell Nucleus ; Animals ; Cell Nucleus ; metabolism ; Forkhead Box Protein O3 ; metabolism ; Mice ; Mice, Knockout ; Muscle, Skeletal ; metabolism ; pathology ; Muscular Atrophy ; metabolism ; pathology ; Protein-Serine-Threonine Kinases ; deficiency ; metabolism

BACKGROUNDLipid storage myopathy (LSM) is a genetically heterogeneous group with variable clinical phenotypes. Late-onset multiple acyl-coenzyme A dehydrogenation deficiency (MADD) is a rather common form of LSM in China. Diagnosis and clinical management of it remain challenging, especially without robust muscle biopsy result and genetic detection. As the noninvasion and convenience, muscle magnetic resonance imaging (MRI) is a helpful assistant, diagnostic tool for neuromuscular disorders. However, the disease-specific MRI patterns of muscle involved and its diagnostic value in late-onset MADD have not been systematic analyzed.

METHODSWe assessed the MRI pattern and fat infiltration degree of the lower limb muscles in 28 late-onset MADD patients, combined with detailed clinical features and gene spectrum. Fat infiltration degree of the thigh muscle was scored while that of gluteus was described as obvious or not. Associated muscular atrophy was defined as obvious muscle bulk reduction.

RESULTSThe mean scores were significantly different among the anterior, medial, and posterior thigh muscle groups. The mean of fat infiltration scores on posterior thigh muscle group was significantly higher than either anterior or medial thigh muscle group (P < 0.001). Moreover, the mean score on medial thigh muscle group was significantly higher than that of anterior thigh muscle group (P < 0.01). About half of the patients displayed fat infiltration and atrophy in gluteus muscles. Of 28 patients, 12 exhibited atrophy in medial and/or posterior thigh muscle groups, especially in posterior thigh muscle group. Muscle edema pattern was not found in all the patients.

CONCLUSIONSLate-onset MADD patients show a typical muscular imaging pattern of fat infiltration and atrophy on anterior, posterior, and medial thigh muscle groups, with major involvement of posterior thigh muscle group and gluteus muscles and a sparing involvement of anterior thigh compartment. Our findings also suggest that muscle MRI of lower limbs is a helpful tool in guiding clinical evaluation on late-onset MADD.

Adolescent ; Adult ; Age of Onset ; Child ; Child, Preschool ; Electron-Transferring Flavoproteins ; genetics ; Female ; Humans ; Lipid Metabolism, Inborn Errors ; genetics ; metabolism ; pathology ; Lower Extremity ; pathology ; Magnetic Resonance Imaging ; Male ; Middle Aged ; Muscle, Skeletal ; metabolism ; pathology ; Muscular Atrophy ; genetics ; metabolism ; pathology ; Muscular Dystrophies ; genetics ; metabolism ; pathology ; Mutation ; genetics ; Young Adult

Changes in the respiratory system caused by aging generally include structural changes in the thoracic cage and lung parenchyma, abnormal findings on lung function tests, ventilation and gas exchange abnormalities, decreased exercise capacity, and reduced respiratory muscle strength. Decreased respiratory system compliance caused by reduced elastic recoil of the lung parenchymaand thoracic cage is related to decreased energy expenditure by the respiratory system. Lung function, as measured by 1-second forced expiratory volume and forced vital capacity (FVC), decreases with age, whereas total lung capacity remains unchanged. FVC decreases because of increased residual volume and diffusion capacity also decreases. Increased physiological dead space and ventilation/perfusion imbalance may reduce blood oxygen levels and increase the alveolar-arterial oxygen difference. More than 20% decrease in diaphragmstrength is thought to beassociated withaging-related muscle atrophy. Ventilation per minute remains unchanged, and blood carbon dioxide concentration does not increase with aging. However, responses to hypoxia and hypercapnia are decreased. Exercise capacity also decreases, and maximum oxygen consumption decreases by >1%/year. Consequence of these changes, many respiratory diseases occur with aging. Thus, it is important to recognize these aging-related respiratory system changes.
Aging* ; Anoxia ; Carbon Dioxide ; Compliance ; Diffusion ; Energy Metabolism ; Forced Expiratory Volume ; Hypercapnia ; Lung ; Muscular Atrophy ; Oxygen ; Oxygen Consumption ; Residual Volume ; Respiratory Function Tests ; Respiratory Muscles ; Respiratory System* ; Total Lung Capacity ; Ventilation ; Vital Capacity

OBJECTIVETo observe the effect of Shenshuai Yingyang Capsule (SSYYJN) in ameliorating muscle atrophy in rats with chronic renal failure (CRF) and explore the role of Wnt7a-Akt/mTOR signal pathway in mediating this effect.

METHODSMale rats were randomly assigned to 5/6 nephrectomy group and sham-operated group, and the former group was further randomly divided into CRF model group, KA group, and SSYYJN group. The size of anterior tibia muscle was examined microscopically with HE staining. Protein synthesis in the soleus muscle was investigated by (14)C-phenylalanine experiment, and the expression of Wnt7a, frizzled-7, phospho-Akt, phospho-mTOR and GAPDH were detected with Western blotting.

RESULTSThe body weight, the wet and dry weight, cross-sectional area, and muscle protein synthesis of the anterior tibia muscles, and expressions of the proteins in the Wnt7a/Akt signaling pathway all increased significantly in SSYYJN and KA groups as compared with those in the model group.

CONCLUSIONSSYYJN can effectively improve muscle atrophy in the rat model of CRF possibly by reversing the reduction in the expressions of Wnt7a/Akt signaling pathway proteins in the skeletal muscles.

Animals ; Capsules ; Drugs, Chinese Herbal ; pharmacology ; Kidney Failure, Chronic ; complications ; Male ; Muscle Proteins ; biosynthesis ; Muscle, Skeletal ; drug effects ; Muscular Atrophy ; drug therapy ; Nephrectomy ; Proto-Oncogene Proteins ; metabolism ; Rats ; Signal Transduction ; TOR Serine-Threonine Kinases ; metabolism ; Wnt Proteins ; metabolism

PURPOSE: The purpose of this study was to examine the effects of Cu/Zn SOD on reduction of hindlimb muscular atrophy induced by cisplatin in rats. METHODS: Forty-two rats were assigned to three groups; control group, Cisplatin (CDDP) group and cisplatin with Cu/Zn SOD (CDDP-SOD) group. At day 35 hindlimb muscles were dissected. Food intake, activity, withdrawal threshold, muscle weight, and Type I, II fiber cross-sectional area (CSA) of dissected muscles were measured. Relative SOD activity and expression of MHC and phosphorylated Akt, ERK were measured after dissection. RESULTS: Muscle weight and Type I, II fiber CSA of hindlimb muscles in the CDDP group were significantly less than the control group. Muscle weight and Type I, II fiber CSA of hindlimb muscles, food intake, activity, and withdrawal thresholds of the CDDP-SOD group were significantly greater than the CDDP group. There were no significant differences in relative SOD activities of hindlimb muscles between the CDDP-SOD and CDDP groups. MHC expression and phosphorylated Akt, ERK of hindlimb muscles in the CDDP-SOD group were significantly greater than the CDDP group. CONCLUSION: Cu/Zn SOD attenuates hindlimb muscular atrophy induced by cisplatin through increased food intake and activity. Increment of phosphorylated Akt, ERK may relate to attenuation of hindlimb muscular atrophy.
Animals ; Body Weight/drug effects ; Cisplatin/*toxicity ; Disease Models, Animal ; Extracellular Signal-Regulated MAP Kinases/metabolism ; Hindlimb ; Male ; Muscle, Skeletal/*drug effects/enzymology/metabolism ; Muscular Atrophy/*chemically induced/metabolism/pathology ; Phosphorylation ; Proto-Oncogene Proteins c-akt/metabolism ; Rats ; Rats, Sprague-Dawley ; Recombinant Proteins/biosynthesis/genetics/pharmacology ; Superoxide Dismutase/genetics/metabolism/pharmacology ; Superoxides/metabolism