The mechanisms of type 2 diabetic skeletal muscle atrophy and the effects of commonly used hypoglycemic drugs: a review / 药学学报

Type 2 diabetes is a hypermetabolic disease characterized with disorders of glucose/lipid metabolism, absolute or relative lack of insulin, and can induce skeletal muscle atrophy. Hyperglycemia, hyperlipidemia, insulin resistance, and abnormal release of inflammatory factors can lead to abnormal signal transduction in skeletal muscle, thus make protein synthesis and degradation imbalance and eventually causing muscle atrophy. Under normal conditions, insulin-like growth factor 1 (IGF-1)/insulin can activate phosphoinositide 3-kinase (PI3K)/protein kinase B (AKT). AKT not only increases protein synthesis through mammalian target protein of rapamycin (mTOR), but also phosphorylates forkhead box O (FoxO) transcription factor and then inhibits the transcription of several ubiquitin ligases (such as MAFbx/atrogin-1 and MuRF1), or autophagy related genes. The weakened IGF-1/PI3K/AKT pathway in type 2 diabetes is an important factor leading to skeletal muscle atrophy. Studies have shown that the commonly used anti-type 2 diabetic drugs have different effects in regulating the synthesis and degradation of skeletal muscle protein. Studies reported that drugs with effect of anti-diabetic muscle atrophy include thiazolidinediones, glucagon-like peptide analogs, glucose-sodium cotransporter 2 inhibitors, etc.; drugs that are still in controversial or even promote skeletal muscle atrophy include metformin, and some sulfonylurea or non-sulfonylurea insulin secretagogues. This article overviewed and analyzed the currently commonly used drugs for type 2 diabetes and summarized the related mechanisms, with the aim to provide references for the rational applications of drugs for type 2 diabetes.

Study Progress in Pathogenesis of Cancer Cachexia and Prevention and Treatment with Traditional Chinese Medicine / 中国实验方剂学杂志

Objective:The incidence rate of cancer cachexia is high in late stage of cancer， which is characterized by skeletal muscle atrophy and rapid reduction of adipose tissue and systemic inflammation. Cachexia is highly related to a variety of tumors， and causes a large proportion of cancer deaths. Cancer cachexia can lead to serious complications in patients with cancer， then， the quality of life of patients decreases， the psychological state becomes negative， and the state of illness is further worsened. At present， there is no effective intervention means to completely reverse cachexia. The combined use of multiple targets and effective components of traditional Chinese medicine（TCM）， as well as the treatment based on syndrome differentiation and the theory of TCM play an important role in the prevention and treatment of cancer cachexia. Therefore， exploring the pathogenesis of cancer cachexia and prevention and treatment with TCM is helpful for basic study and clinical application. Method:In this paper， cancer cachexia and TCM in China national knowledge infrastructure （CNKI） and Public Medline （PubMed） databases were retrieved， and 98 Chinese and English literatures were included through summarization to elaborate the pathogenesis of cancer cachexia and the prevention and treatment of TCM. Result:Emphasis was given to the important role of inflammatory reaction， skeletal muscle atrophy， energy metabolism abnormality and multiple signal joint regulation in occurrence of cancer cachexia， and the unique advantages and significant role of TCM in treatment of cancer cachexia under different treatment principles. Conclusion:Inflammatory reaction， skeletal muscle atrophy， abnormal energy metabolism make the pathogenesis of cancer cachexia complex and diverse. TCM prescriptions， Chinese herbal medicine and their effective ingredients have the natural advantages of targeting multiple pathways， controlling multiple signal pathways and inhibiting various inflammatory factors in the prevention and treatment of cancer cachexia， and are safe and effective in improving diet， prolonging the survival period of patients and keeping weight.

The mechanisms and treatments of muscular pathological changes in immobilization-induced joint contracture: A literature review / 中华创伤杂志(英文版)

The clinical treatment of joint contracture due to immobilization remains difficult. The pathological changes of muscle tissue caused by immobilization-induced joint contracture include disuse skeletal muscle atrophy and skeletal muscle tissue fibrosis. The proteolytic pathways involved in disuse muscle atrophy include the ubiquitin-proteasome-dependent pathway, caspase system pathway, matrix metalloproteinase pathway, Ca-dependent pathway and autophagy-lysosomal pathway. The important biological processes involved in skeletal muscle fibrosis include intermuscular connective tissue thickening caused by transforming growth factor-β1 and an anaerobic environment within the skeletal muscle leading to the induction of hypoxia-inducible factor-1α. This article reviews the progress made in understanding the pathological processes involved in immobilization-induced muscle contracture and the currently available treatments. Understanding the mechanisms involved in immobilization-induced contracture of muscle tissue should facilitate the development of more effective treatment measures for the different mechanisms in the future.

Effect of Tuina on Autophagy-related Factor Beclin-1, Vacuolar Protein Sorting and Microtubule-associated Protein Light Chain 3 in Rats with Denervated Skeletal Muscle Atrophy / 中国康复理论与实践

Objective:To explore the effect and mechanism of Tuina on denervated skeletal muscle atrophy. Methods:A total of 77 male Sprague-Dawley rats were randomly divided into sham group (n = 7), model group (n = 35) and Tuina group (n = 35). The latter two groups were established skeletal muscle atrophy model by exposing and cutting off the common tibial nerve of rats. One day after modeling, the lower limbs of the surgical side received Tuina in Tuina group. Separately, the surgical side of gastrocnemius muscle were sampled on the 0th, 7th, 14th, 21st and 28thday after modeling, and measured the wet mass ratio. The cross-sectional area and diameter of muscle fiber were measured after HE staining. The mRNA expression of autophagy-realated factor Beclin-1, vacuolar protein sorting (Vps34) and microtubule-associated protein light chain 3 (LC3) were tested with reverse transcription real-time quantitative polymerase chain reaction. Results:There was no statistical difference in the ratio of gastrocnemius wet weight, the cross-sectional area and diameter of muscle fiber, and the mRNA expression of Beclin-1, Vps34 and LC3 among three groups on the 0th day (F < 1.321, P > 0.05). Compared with the sham group, the ratio of gastrocnemius wet weight, the cross-sectional area and diameter of muscle fiber decreased at different time points in the model group and Tuina group (P < 0.05), the ratio of gastrocnemius wet weight was higher, and the cross-sectional area and diameter of muscle fiber were bigger, both except on the 21st day, in Tuina group than in the model group (P < 0.05). Compared with the sham group, the mRNA expression of Beclin-1, Vps34 and LC3 increased at different points in the model group than in Tuina group (P < 0.05), and all the mRNA expression was higher, except on the 14th day, in Tuina group than in the model group (P < 0.05). The ratio of gastrocnemius wet weight, the cross-sectional area and diameter of muscle fiber showed a trend of progressive decrease with time in the model group and Tuina group (P < 0.05). The mRNA expression of Beclin-1 and Vps34 increased (P < 0.05), and the mRNA expression of LC3 increased in the model group 21 days after intervention (P < 0.05). The mRNA expression of Beclin-1, Vps34 and LC3 increased first and then decreased, except the mRNA expression on the 14th day in Tuina group (P < 0.05). Conclusion:Tuina may promote the activation of autophagy by up-regulating the expression of autophagy-realated factor Beclin-1, Vps34 and LC3, remove the damaged organelles and proteins, provide certain synthetic substrate and energy for muscle fiber regeneration, thereby reduce the loss of degree of denervated skeletal muscle atrophy.

Experimental Research Progress on Acupuncture in Skeletal Muscle Atrophy (review) / 中国康复理论与实践

@# Irrespective of physiological or pathological skeletal muscle atrophy, the endocrine and motor functions of skeletal muscle are impaired. The mechanism of acupuncture to prevent and treat skeletal muscle atrophy is not only related to classical protein synthesis and decomposition, but also involves apoptosis, autophagy, muscle satellite cell proliferation and differentiation, muscle fiber type conversion, neuromuscular junction conduction, and cell energy metabolism conversion.

Effects of Electroacupuncture on Mammalian Target of Rapamycin/70-KD Ribosomal Protein S6 Kinase Pathway in Gastrocnemius Muscle in Denervated Rats / 中国康复理论与实践

@#Objective To explore the effects and mechanism of electroacupuncture (EA) on denervation-induced atrophy in rats. Methods A total of 18 male Sprague-Dawley rats were divided into sham group (n=6), model group (n=6) and EA group (n=6). The latter two groups were clamped right sciatic nerve to establish atrophy model of skeletal muscle. On the second day after modeling, EA group accepted electroacupuncture on right Zusanli (ST36) and Huantiao (GB30) for two weeks. Their gastrocnemius muscles were obtained after intervention, and the wet weight ratio of the gastrocnemius muscles was calculated. The cross-sectional area (CSA) and diameter of muscle fibers were measured after HE staining. The protein expression of mammalian target of rapamycin (mTOR), phosphorylated mTOR (p-mTOR), 70-KD ribosomal protein S6 kinase (p70S6K) and phosphorylated p70S6k (p-p70S6k) was tested with Western blotting. The gene expression of mTOR and p70S6K was detected with real-time quantitative polymerase chain reaction. Results Compared with the sham group, the wet weight ratio of the gastrocnemius muscle, CSA and diameter of the muscle fibers decreased in the model group and EA group (P<0.001), which were more in EA group than in the model group (P<0.01); the protein expression of mTOR, p-mTOR, p70S6K and p-p70S6K increased in the model group (P<0.01), and increased more in EA group (P<0.05); the gene expression of mTOR and p70S6K increased in the model group (P<0.05) , and increased more in EA group (P<0.05).Conclusion Electroacupuncture delays the atrophy of denervated skeletal muscles, which may relate to activation of mTOR/p70S6K signal pathway to impact synthesis of skeletal muscle proteins.

Effect of Tuina and Treadmill Training on Skeletal Muscle Atrophy after Denervation in Rats / 中国康复理论与实践

@# Objective To explore the effect of the combination of Tuina and treadmill training on denervation skeletal muscle atrophy. Methods A total of 80 Sprague-Dawley rats (one month old) were randomly divided into control group (n=40) and manipulation group (n=40). Their sciatic nerves were transected, and the manipulative group accepted treadmill training and kneading of Tuina, while the control group accepted no intervention. Their muscle wet weight ratio, muscle satellite cells and insulin-like growth factor I (IGF-I) positive cells count were measured, and HE staining of gastrocnemius muscle were observed one, two, three and four months after intervention, ten rats in each group. Results Compared with the control group, the muscle wet weight ratio decreased three months after intervention (F=4.590, P<0.05), muscle satellite cells increased three months after intervention (F=12.466, P<0.01), and IGF-I positive cells increased two, three and four months after intervention (F>6.489, P<0.05). HE staining showed the skeletal muscle injury relieved somehow.Conclusion The combination of Tuina and treadmill training can relieve denervation skeletal muscle injury, but it is not enough for skeletal muscle atrophy, which may associate with promoting the expression of muscle satellite cells and IGF-I.

Advance in Model Establishment for Denervated Skeletal Muscle Atrophy (review) / 中国康复理论与实践

The skeletal muscle atrophy could be induced by the injury of nerve. According to the source of denervated skeletal mus-cle atrophy, it could be divided into exogenous muscle atrophy and endogenous muscle atrophy. In recent years, the ex-ogenous muscle atrophy models are mainly established by operating, physically injuring or chemically injuring, while the endogenous muscle atrophy models are mainly established by the transgenic animals of amyotrophic lateral sclero-sis. The selection and optimazation of animal models are crucial for the basic studies of denervated skeletal muscle atro-phy.

The evolution of the denervated gastrocnemii and it's miR-206 and myoD expression during skeletal muscle atrophy in rats / 中华显微外科杂志

Objective To investigate the expression pattern of skeletal muscle specific miR-206,myogenesis related myoD which change with time in dcnervated muscle atrophy rats.Methods From June,2015 to January,2016,40 SPF sprague-dawley rats were equally classified into 5 groups randomly according to standard settled before,5 groups were separately defined as denervated 0d group,denervated 1d group,denervated 7d group,denervated 14d group,and denervated 28d group.Each group contained 8 rats.The rats atrophy models were established by cutting sciatic never on left side.According to the different denervated time,the gastrocnemii on both sides were obtained under anesthesia,respectively.The wet weight ratio of two compared gastrocnemii were measured,and the gastrocnemii transection was observed by HE stain,measured the expression of myoD protein by western blot,obtained the expression of miR-206,myoD mRNA by qPCR.Results According to our study on rats denervated atrophy models,the wet ratio of compared gastrocnemius would decrease rapidly,by HE stain,decease of cross sectional area in muscle fiber was observed as well as degeneration.Collagen fibers hyperplasia appeared and increased with time change.Wet ratio and transaction aera ratio of group Od,1d,7d,14d,28d were 0.99±0.04,0.92±0.07,0.68±0.11,0.39±0.06,0.27±0.07 and 0.99±0.02,0.96±0.04,0.51±0.09,0.34±0.08,0.23±０.03 respectively,difference between experimental groups and control group were statistically significant (P＜ 0.05),the differences between each experimental groups were also statistically significant (P＜ 0.05).After qPCR test of miR-206,myoD mRNA expression,it was found that their expression patterns were similar,miR-206,myoD mRNA increased at first and would reach the expression peak at the 7 th day,after that their contents decreased but still higher at the 14th day when compared with that at the 1 st day.Their expression of group 0d,1 d,7d,14d,28d were 0.24±0.06,0.34±0.04,0.68±0.04,0.49± 0.07,0.25±0.03 and 0.41 ±0.06,0.49±0.09,0.93±0.06,0.66±0.03,0.39±0.04,respectively.All experimental groups were statistically significant different when compared with 0d group except 1d group (P＜ 0.05),the differences between each experimental groups were also statistically significant(P＜ 0.05).The protein expression of myoD was also measured by western blot test,which showed nearly the same expression pattern as the mRNA expression pattern.After injury,the protein expression increased and reached the expression peak at the 7th day.The relative expression of myoD of group 0d,1d,7d,14d,28d measured by grey ratio were 1.03±0.05,1.06±0.06,1.42±0.10,0.66±0.13,0.24±0.07,respectively.The difference between experimental groups and control group were statistically significant (P ＜ 0.05),the differences between each experimental groups were statistically significant (P ＜ 0.05) as well.Conclusion The degree of muscle denervation atrophy was related to the denervated duration in rats.The expression regulation of miR-206 and myoD in gastrocnemius was similar during the muscle denervation atrophy,which suggesting having internal relationship between miR-206 and myoD.

Mechanism of Nuclear Factor-κB in Skeletal Muscle Atrophy during Prevention and Treatment of Exercise in Patients with Chronic Obstructive Pulmonary Disease (review) / 中国康复理论与实践

@#Chronic obstructive pulmonary (COPD) has significant extra pulmonary effects, which could induce atrophy of peripheral skeletal muscle and respiratory muscles, and significantly influence the respiratory function and quality of life. Muscle nuclear factor (NF)-κB activation plays a key role in the skeletal muscle atrophy. This article discussed the potential mechanisms on how NF-κB signaling pathway increasing protein breakdown and reducing muscle regeneration. On this basis, we explored the role of NF-κB in skeletal muscle at-rophy in patients with COPD during exercise.

Molecular Mechanisms of Inhibiting the Muscle Atrophy by Electroacupuncture / 日本温泉気候物理医学会雑誌

 Electroacupuncture (EA) is an acupuncture technique that is stimulated by acupuncture needles with low-frequency microcurrent. The aim of this study is to elucidate the effect of EA and it's molecular mechanism on muscle atrophy by using an animal model: hindlimb-suspended (HS) mice in the disuse muscle atrophy model. To compare the effects of EA in HS mice and HS mice treated with EA (EA/HS), soleus muscle mass and soleus myofiber diameter were measured. We then used real-time quantitative RT-PCR to analyze the expression of myostatin and ubiquitin ligase genes in atrophic muscles of HS mice and in muscles of EA/HS mice. We found that EA/HS mice maintained a soleus muscle mass that was not significantly different from that of wild mice (WT), whereas HS mice had significantly reduced muscle mass. Also, the diameters of myofibers in EA/HS mice, which were not significantly different from wild values, were significantly larger than those in HS mice. Repeated EA treatment suppressed gene expression of myostatin and ubiquitin ligase genes in skeletal muscle of EA/HS mice but induced expression of these genes in HS mice. These findings suggest the molecular mechanism by EA: suppression of myostatin and ubiquitin ligase gene may be a key reaction of inhibiting the disuse muscle atrophy.

Molecular Mechanisms of Inhibiting the Muscle Atrophy by Electroacupuncture / 日本温泉気候物理医学会雑誌

 Electroacupuncture (EA) is an acupuncture technique that is stimulated by acupuncture needles with low-frequency microcurrent. The aim of this study is to elucidate the effect of EA and it's molecular mechanism on muscle atrophy by using an animal model: hindlimb-suspended (HS) mice in the disuse muscle atrophy model. To compare the effects of EA in HS mice and HS mice treated with EA (EA/HS), soleus muscle mass and soleus myofiber diameter were measured. We then used real-time quantitative RT-PCR to analyze the expression of myostatin and ubiquitin ligase genes in atrophic muscles of HS mice and in muscles of EA/HS mice. We found that EA/HS mice maintained a soleus muscle mass that was not significantly different from that of wild mice (WT), whereas HS mice had significantly reduced muscle mass. Also, the diameters of myofibers in EA/HS mice, which were not significantly different from wild values, were significantly larger than those in HS mice. Repeated EA treatment suppressed gene expression of myostatin and ubiquitin ligase genes in skeletal muscle of EA/HS mice but induced expression of these genes in HS mice. These findings suggest the molecular mechanism by EA: suppression of myostatin and ubiquitin ligase gene may be a key reaction of inhibiting the disuse muscle atrophy.

Effects of Different Types of Dietary Fat on Muscle Atrophy According to Muscle Fiber Types and PPARdelta Expression in Hindlimb-Immobilized Rats

This study investigated how dietary fat affects muscle atrophy and lipid metabolism in various muscles during hindlimb immobilization in rats. Twenty-four male Sprague-Dawley rats had their left hindlimb immobilized and were divided into four groups by dietary fat content and composition. The contralateral hindlimb (control) was compared with the immobilized limb in all dietary groups. Rats (n = 6/group) were fed a 4% corn oil diet (CO), 2.6% corn oil + 1.4% fish oil diet (FO), 30% corn oil diet (HCO), or a 30% beef tallow diet (HBT)after their hind limbs were immobilized for 10 days. Data were collected for the gastrocnemius, plantaris and soleus muscles. Muscle atrophy was induced significantly after 10 days of hindlimb immobilization, resulting in significantly decreased muscle mass and total muscle protein content. The protein levels of peroxisome proliferator activated receptor delta (PPARdelta) in the plantaris, gastrocnemius, and soleus increased following hindlimb immobilization irrespective of dietary fat intake. Interestingly, the PPARdelta mRNA level in the plantaris decreased significantly in all groups and that in the FO group was lower than that in the other groups. The soleus PPARdelta mRNA level decreased significantly following hindlimb immobilization in the FO group only. Muscle carnitine palmitoyl transferase 1 (mCPT1) mRNA level was not affected by hindlimb immobilization. However, the mCPT1 mRNA level in the FO group was significantly lower in the plantaris but higher in the soleus than that in the other groups. The pyruvate dehydrogenase kinase 4 (PDK4) mRNA level in the plantaris decreased significantly, whereas that in the soleus increased significantly following hindlimb immobilization. The plantaris, but not soleus, PDK4 mRNA level was significantly higher in the FO group than that in the CO group. The increased PPARdelta protein level following hindlimb immobilization may have suppressed triglyceride accumulation in muscles and different types of dietary fat may have differentially affected muscle atrophy according to muscle type. Our results suggest that omega-3 polyunsaturated fatty acids may suppress muscle atrophy and lipid accumulation by positively affecting the expression level and activity of PPARdelta and PPARdelta-related enzymes, which are supposed to play an important role in muscle lipid metabolism.

Electroacupuncture accelerates recovery of muscle atrophy induced by hindlimb suspension in mouse skeletal muscle / 全日本鍼灸学会雑誌

[Objective]The influence of electroacupuncture (EA) stimulation on physical inactivity is not clear. This study aimed to investigate the effects of EA on the recovery of mouse soleus muscle atrophy induced by hindlimb suspension (HS).<BR>[Methods]We used 8-week-old male ICR mice (n = 20). The mice were divided into 4 groups:the No treatment group (NT, n = 5), HS group (HS, n = 5), Control group (CT, n = 5), and Reloading-with-EA-stimulation group (EA, n = 5). HS mice were suspended for up to 14 days. CT and EA mice were reloaded for an additional 14 days after the HS for 14 days. The HS method used a modified version of an apparatus used in a previous study. EA mice received EA every other day immediately after reloading and were stimulated in the triceps surae muscle at 10 Hz for 30 min with a stainless steel needle. The weight, muscle fiber area size and number of macrophages in the soleus muscle were analyzed.<BR>[Results]The number of skeletal muscle macrophages was increased significantly in EA mice compared with that in CT mice (P < 0.01). The soleus muscle weight and muscle fiber cross-sectional area were decreased in HS mice compared with NT mice (P < 0.01). However, the muscle weight of EA and CT mice increased significantly compared with that of HS mice (P < 0.01). In addition, the muscle weight of EA mice was significantly higher than that of CT mice (P < 0.01), without a significant difference in muscle fiber cross-sectional area between CT and EA mice. <BR>[Conclusion]These results indicate that EA was effective in facilitating the recovery of skeletal muscle atrophy in mice. In addition, resolution of the skeletal muscle atrophy suggested the satellite cell activation by macrophages, because macrophages invaded the skeletal muscle after EA stimulation.

p38 MAPK Participates in Muscle-Specific RING Finger 1-Mediated Atrophy in Cast-Immobilized Rat Gastrocnemius Muscle

Skeletal muscle atrophy is a common phenomenon during the prolonged muscle disuse caused by cast immobilization, extended aging states, bed rest, space flight, or other factors. However, the cellular mechanisms of the atrophic process are poorly understood. In this study, we investigated the involvement of mitogen-activated protein kinase (MAPK) in the expression of muscle-specific RING finger 1 (MuRF1) during atrophy of the rat gastrocnemius muscle. Histological analysis revealed that cast immobilization induced the atrophy of the gastrocnemius muscle, with diminution of muscle weight and cross-sectional area after 14 days. Cast immobilization significantly elevated the expression of MuRF1 and the phosphorylation of p38 MAPK. The starvation of L6 rat skeletal myoblasts under serum-free conditions induced the phosphorylation of p38 MAPK and the characteristics typical of cast-immobilized gastrocnemius muscle. The expression of MuRF1 was also elevated in serum-starved L6 myoblasts, but was significantly attenuated by SB203580, an inhibitor of p38 MAPK. Changes in the sizes of L6 myoblasts in response to starvation were also reversed by their transfection with MuRF1 small interfering RNA or treatment with SB203580. From these results, we suggest that the expression of MuRF1 in cast-immobilized atrophy is regulated by p38 MAPK in rat gastrocnemius muscles.

Effects of Body-weight Support Treadmill Training on Lower Extremity Muscle Atrophy and Ambulatory Capacity in Complete Spinal Cord Injured Patients / 中国康复理论与实践

@#Objective To explore the effect of body-weight support treadmill training(BWSTT)on lower extremity muscle atrophy and ambulatory capacity in complete spinal cord injured(SCI)patients.Methods 20 patients with complete SCI at the thoracic level were divided into control and BWSTT group.They all received comprehensive rehabilitation,and patients in BWSTT group also received BWSTT for 3 months when the physical condition was permitted.They were assessed before and after treatment with measurement of thigh girth,ambulatory capacity measure of Functional Independence Measure(FIM),10 meters ambulatory velocity and activity of daily living(ADL)evaluation.Patients in BWSTT group also received middle thigh MRI examination before and after BWSTT.Results The muscles at the mid-thigh of the BWSTT group looked larger after BWSTT than before.The scores of FIM ambulatory function,the 10 miters ambulatory velocity of BWSTT group improved significantly when compared with that of the control group(P<0.05).The thigh girth and the scores of ADL were no different between these two groups before and after treatment(P<0.05).Conclusion BWSTT may ameliorate lower extremities skeletal muscle atrophy and improve ambulatory capacity for SCI patients.

Gene Expression Modulation in Rat Skeletal Muscle by Denervation-induced Atrophy / 대한정형외과연구학회지

PURPOSE: To understand the modulation of genes by atrophy, differential expression of genes in normal and denervated skeletal muscle was investigated by DNA chip technology. MATERIALS AND METHODS: Sciatic nerve and femoral nerve were resected in right leg of rat to make the muscle atrophy model. Muscle tissues from the gastrocnemius of normal and denervated legs were homogenized and RNA were extracted. Dyes were labelled during reverse transcription and hybridization was done into the DNA chip which is consisted of about 5,000 probes. RESULTS: By statistical analysis, 39 genes were selected as differentially expressed genes by atrophy. 15 known genes up-regulated by atrophy were genes related to immune response, extracellular matrix, andsignal transduction in plasma membrane. 7 known genes down-regulated by atrophy were genes related to cell growth and proliferation, intracellular signal transduction, and energy metabolism. Some unknown gene functions were analysed by bioinformatics analysis and they were highly homologous genes with McKusick-Kaufman syndrome protein, ADP-ribosylation factor-like 4, and component X of pyruvate dehydrogenase complex. CONCLUSION: These results suggest that reduction of energy metabolism, activation of cholesterol exclusion, and changes on signal transduction pathway are involved in the process of atrophy by denervation in skeletal muscle of rat.

Comparison of Morphological Features in Soleus between Tail-suspended and 30-month-old Rats / 航天医学与医学工程

Objective To compare the morphological differences in soleus between tail-suspended and 30-month-old rats.Methods Fourty-two male rats were randomly divided into seven groups:5 d,7 d and 14 d tail-suspended and their synchronous control groups,30-month-old group.The cross-sectional area(CSA)and percentage of MHC Ⅰ/Ⅱ fibers were measured in immunohistochemically stained sections and CSA was normalized by body weight.Results Wet weight,relative wet weight,CSA and normalized CSA in unloaded soleus decreased significantly as compared with the synchronous control.The percentage of MHC Ⅰ fibers decreased,but that of MHC Ⅱ fibers increased in unloaded soleus.The wet weight and CSA of soleus in 30-month-old rats increased,but the relative wet weight and normalized CSA reduced significantly as compared with 14-day synchronous control.The relative wet weight and normalized CSA of soleus in 30-month-old rat were similar to that of 14 d tail-suspended group.The percentage of MHC Ⅰ/Ⅱ fibers of soleus in 30-month-old rat and in 5 d,7 d,and 14 d of synchronous control groups kept constant value.Conclusion It's suggested that the atrophic process of soleus is slower in 30-month-old rats than that in the tail-suspended rates.The reduction of soleus relative wet weight and normalized CSA appears early in aged rats,but the absolute and relative wet weight of soleus decrease simultaneously in tail-suspended rats.