氯化胆碱与制动性骨骼肌萎缩肌肉生成抑制素mRNA的表达

背景：研究发现类胆碱物质可增加乙酰胆碱的弥散及终板电流的幅度,对神经肌肉接点功能退化有一定的对抗作用。 目的：观察氯化胆碱对制动性骨骼肌萎缩的防治作用及对骨骼肌萎缩大鼠肌肉生成抑制素mRNA表达的影响。 方法：将30只雄性SD大鼠随机分为对照组、模型组和治疗组,每组10只。采用可塑性石膏固定模型组和治疗组大鼠右后肢制备肌萎缩模型。治疗组每日灌胃氯化胆碱(150 mg/kg),对照组和模型组灌胃等体积蒸馏水。4周后解剖右后肢腓肠肌,检测腓肠肌收缩张力、肌湿质量、蛋白质水平及肌肉生成抑制素mRNA的表达。 结果与结论：与对照组比较,模型组大鼠腓肠肌的收缩张力、肌湿质量、蛋白质水平均显著降低(P < 0.05或P < 0.01),肌肉生成抑制素mRNA表达显著增高(P < 0.01)。与模型组比较,治疗组大鼠腓肠肌的收缩张力、肌湿质量、蛋白质水平均显著升高(P < 0.05),肌肉生成抑制素mRNA表达显著降低(P < 0.05)。说明氯化胆碱能够显著提高制动性萎缩骨骼肌的收缩张力、肌湿质量、蛋白质水平,减少肌肉生成抑制素mRNA的表达,从而有效抑制骨骼肌制动性萎缩的发生。     

被动运动对脊髓损伤大鼠后肢运动功能及骨骼肌的影响

目的　观察被动运动促进脊髓损伤（Spinal cord injury, SCI）大鼠后肢运动功能恢复和改善骨骼肌萎缩的影响;探讨脑源性神经营养因子（BDNF）对被动运动促进功能恢复和延缓肌萎缩的作用。 方法　将36只健康成年雌性SD大鼠随机分假手术组、对照组（未行运动）,被动运动组（损伤1周后开始被动运动,共4 周）。采用改良的Allen’s法制备SCI模型。术后1 d和1、2、3、4 周通过大鼠Basso-Beattie-Bresnahan(BBB)行为学评分检测各组大鼠的运动功能;术后5周,采用HE染色比较各组大鼠脊髓组织病理变化,观察大鼠后肢腓肠肌的横断面积、直径和形态变化。测量腓肠肌湿重、体重和肌湿重/体重,评价肌萎缩情况;采用Western blots检测腓肠肌中BDNF的表达变化。 结果　被动运动组运动功能明显高于对照组（P<0.05）。损伤5周后,对照组和被动运动组的脊髓组织失去正常形态,神经元数量减少,损伤区大量空洞形成,而被动运动组的变化较对照组轻。对照组腓肠肌湿重、肌湿重/体重、横断面积和直径下降,被动运动组改善上述肌萎缩情况（P<0.05）。与假手术组相比,对照组和被动运动组BDNF表达量增加（P<0.05）,其中被动运动组高于对照组（P<0.05）。 结论　被动运动可能是通过增加SCI后BDNF表达促进损伤后运动功能的恢复,并能有效改善失神经性肌萎缩。     

失神经骨骼肌萎缩中泛素蛋白连接酶Murf1和核转录因子NF-κB表达与被动运动干预

背景:蛋白质分解是延缓肌萎缩发生的关键环节,在慢性病性、制动性肌萎缩中泛素蛋白连接酶Murf1和核转录因子NF-κB的表达增加,被动运动已被证实可以有效抑制肌萎缩的发生。目的:探讨泛素蛋白连接酶Murf1和核转录因子NF-κB在大鼠失神经肌萎缩中不同时段的表达,以及被动运动对失神经骨骼肌Murf1和NF-κB表达的影响。方法:假手术组大鼠不切断右下肢坐骨神经,失神经组、失神经被动运动组大鼠切断右下肢坐骨神经。术后1d起,将失神经被动运动组大鼠置于自制的网夹内,拉出右后肢,抓住趾部,与脊柱呈45°向后外方牵拉,至右后肢完全伸直,再将右后肢推向身体,使之完全屈曲紧贴身体,每天训练2次,每次屈伸运动300下,3min/次,直至切取标本之日。干预2,14,28d后,采用RT-PCR与WesternBlot技术分别检测Murf1,NF-κBmRNA和蛋白质的表达。结果与结论:与假手术组比较,各时间点失神经组Murf1,NF-κBmRNA及蛋白的表达均明显增加(P0.05);与失神经组比较,各时间点失神经被动运动组Murf1及NF-κBmRNA的表达均显著降低(P0.01)。失神经支配后肌湿质量比明显下降,被动运动14d时肌湿质量比明显高于失神经组(P0.05)。失神经腓肠肌中Murf1,NF-κBmRNA和蛋白的表达与肌湿质量呈负相关(r=-0.795,P0.01;r=-0.834,P0.01),提示被动运动可能通过降低Murf1和NF-κB的表达发挥肌萎缩防治作用。     

有氧训练大鼠腓肠肌组织微小RNA-133a和肌细胞增强因子2的表达***

背景：研究表明微小RNA-133a、肌细胞增强因子2和成肌分化抗原可调解骨骼肌的分化与重塑。 目的：观察有氧训练对腓肠肌微小RNA-133a、肌细胞增强因子2和成肌分化抗原表达的影响。 方法：将SD大鼠随机分为对照组和有氧训练组,有氧训练组采用大鼠跑台运动模型,而对照组不进行运动训练。训练4,6周后采集各组大鼠腓肠肌组织,并称取腓肠肌的质量,实时定量PCR检测骨骼肌中肌球蛋白、微小RNA-133a、肌细胞增强因子2与成肌分化抗原mRNA的表达,并采用免疫组织化学的方法检测腓肠肌Ⅱ型肌纤截面积的改变。         结果与结论：训练4,6周,有氧训练组大鼠腓肠肌的相对质量以及肌球蛋白重链-Ⅱa的表达水平较对照组显著增加(P < 0.05或P < 0.01),Ⅱ型肌纤维横截面积即显著增大(P < 0.05),其微小RNA-133a和肌细胞增强因子2 mRNA的表达较对照组显著升高(P < 0.05,P < 0.01),而成肌分化抗原mRNA的表达在各组间差异均无显著性意义。证实,有氧训练可上调大鼠腓肠肌组织微小RNA-133a、肌细胞增强因子2 mRNA的表达。     

低频电刺激对坐骨神经损伤大鼠不同类型骨骼肌萎缩及内源性胰岛素样生长因子1表达的影响

背景：低频电刺激可以缓解骨骼肌的萎缩,但对肌纤维类型的影响尚不清楚,同时内源性胰岛素样生长因子1在萎缩后的肌纤维中的表达与电刺激的关系尚无公识。 目的：观察低频电刺激对坐骨神经损伤大鼠不同类型骨骼肌纤维萎缩情况及内源性胰岛素样生长因子1表达的影响。 方法：将健康雄性SD大鼠随机分为3组,切断模型组和电刺激组大鼠左侧坐骨神经制备失神经支配模型,适应5 d后,对电刺激组大鼠损伤侧腓肠肌施以2 Hz的电刺激,2次/d,每次持续20 min,正常组和模型组常规饲养。30 d后,取大鼠腓肠肌腹部,检测其肌纤维直径和数量;免疫组织化学法检测肌组织中胰岛素样生长因子1的水平。 结果与结论：失神经支配后,大鼠腓肠肌Ⅰ、Ⅱ型肌纤维直径减小,Ⅰ型肌纤维数比例增大。与模型组比较,电刺激组大鼠腓肠肌Ⅰ、Ⅱ型肌纤维直径有所增大,尤以Ⅰ型肌纤维直径增大更明显(P < 0.05)。同时,电刺激组大鼠腓肠肌中胰岛素样生长因子1的表达也明显高于模型组(P < 0.05)。提示,2 Hz的电刺激可促进胰岛素样生长因子1的表达,减轻Ⅰ型肌纤维的萎缩。     

Myostatin在小鼠腓肠肌失神经支配萎缩过程中的表达

目的:分析myostatin在腓肠肌失神经支配萎缩过程中的表达变化及其在肌萎缩过程中的作用。方法:采用坐骨神经横断术制备小鼠腓肠肌失神经支配模型,实时荧光定量PCR和Western印迹法分别检测失神经支配不同时段腓肠肌myostatin mRNA和蛋白表达水平,并对失神经前后肌肉湿重比、肌纤维横截面积进行比较。结果:失神经支配1 d时,腓肠肌myostatin mRNA迅速上升,3 d达到高峰,随后逐渐下降,而相应蛋白水平逐渐增高,7 d达到高峰继而逐渐下降,至56 d时mRNA和蛋白水平仍略高于正常水平。结论:腓肠肌失神经支配萎缩过程中myostatin的表达变化是一重要的分子事件。     

骨髓间充质干细胞移植治疗失神经肌萎缩

背景:外科显微镜手术和一些辅助治疗方法均无法通过修复损伤的神经细胞来有效延缓或治疗失神经肌萎缩。研究发现骨髓间充质干细胞具有定向分化潜能,并且在一定环境因素下能对损伤的组织进行修复,由此推测其可以对失神经萎缩肌肉起到一定的修复作用。目的:探讨移植骨髓间充质干细胞是否能够减轻和延缓失神经肌肉组织萎缩。方法:分离培养SD大鼠骨髓间充质干细胞,取第3代骨髓间充质干细胞经BrdU标记后用于移植治疗。将30只SD大鼠分为3组,每组10只,对每只大鼠左后肢进行手术。假手术组只暴露坐骨神经主干,不钳夹神经,移植治疗组、模型对照组钳夹坐骨神经主干后,向其支配的腓肠肌注射骨髓间充质干细胞悬液和不含胎牛血清的DMEM培养液。骨髓间充质干细胞移植后1,2周,采用BBB评分评价各组大鼠左后肢运动功能;骨髓间充质干细胞移植后14 d,取腓肠肌组织进行苏木精-伊红染色和BrdU免疫组化染色。结果与结论:第3代骨髓间充质干细胞BrdU标记为阳性;标记的骨髓间充质干细胞能在移植治疗组失神经损伤的肌肉组织中存活并起修复作用;相对于模型对照组,移植治疗组失神经肌纤维由相互融合重新恢复规整。结果表明移植骨髓间充质干细胞能够减轻和延缓失神经肌肉组织萎缩。     

常氧、低氧训练条件下肌肉蛋白表达及肌张力的变化

背景：环境因素以及运动水平均可显著引起肌纤维结构的变化。 目的：观察常氧、低氧训练条件下大鼠腓肠肌肌球蛋白、肌动蛋白的表达及肌张力的变化特征。 方法：将SD大鼠随机分为常氧对照组(氧体积分数20%,不进行任何处理)、常氧训练2,4,6周组、低氧训练2,4,6周组、低氧对照组(氧体积分数12.7%,不进行训练)。 结果与结论：无论在常氧还是低氧环境下,运动训练后大鼠腓肠肌质量、腓肠肌肌纤维截面积均明显增加(P < 0.05,P < 0.01);运动训练6周后大鼠腓肠肌等长收缩最大张力显著增加(P < 0.01);经运动训练后大鼠腓肠肌总MHC及α-actin随着训练时间的延长逐步升高,并且低氧训练组升高幅度高于常氧训练组。说明低氧训练可以更有效促进骨骼肌肌球蛋白、肌动蛋白的表达,增强肌张力,强化Ⅰ型肌纤维,并且训练时间越长,效果越显著,表明低氧训练是一种有效的运动训练途径。     

柚皮素调控巨噬细胞极化和肌卫星细胞增殖修复骨骼肌损伤

背景：研究表明,巨噬细胞的极化精确调控在组织损伤的修复进程中十分重要,肌卫星细胞增殖及分化在骨骼肌损伤的修复中也有重要作用,并显示柚皮素能改善骨骼肌损伤修复中的过度纤维化。目的：探讨柚皮素对于骨骼肌修复的作用及其机制,为用于骨骼肌损伤提供理论依据。方法：取80只10周龄SPF级SD大鼠随机分为2组(n=40),采用重物击打方法构建骨骼肌损伤模型后,实验组腹腔注射柚皮素(2μg/g)14 d,对照组注射等剂量1%二甲基亚砜。于伤后12 h及1,3,5,7,14 d分别每组采集6只大鼠腓肠肌。Masson和苏木精-伊红染色观测骨骼肌组织纤维化程度;酶联免疫吸附法(ELISA)检测炎症因子白细胞介素4、白细胞介素13、干扰素α、干扰素γ表达;实时荧光定量PCR检测促纤维化基因(Ⅰ、Ⅲ型胶原蛋白)和成肌分化抗原的m RNA表达;流式细胞术检测巨噬细胞极化程度;免疫荧光(Pax7、成肌分化抗原)染色观察肌卫星细胞增殖情况。结果与结论：(1)组织学观察：伤后5,7,14 d时实验组纤维化面积比值低于对照组(P <0.05),再生肌纤维百分比均明显大于对照组(P <0.05);(2)EL...     

失神经支配的骨骼肌萎缩与防治

背景:随着当今医学的发展,失神经支配骨骼肌萎缩的防治已取得了显著的进步,但临床疗效仍不十分满意。目的:对失神经支配骨骼肌萎缩防治方法的研究现状作一总结,试图寻找更为有效的失神经支配骨骼肌萎缩防治方法。方法:以denervation,muscle atrophy,treatment为检索词,检索Medline数据库(1998-01/2008-01)。以失神经,肌萎缩,治疗为检索词,检索中国期刊全文数据库(1998-01/2008-01)、万方数据库(1998-01/2008-01)和《中国临床康复》杂志(1998-01/2008-01)。文献检索语种限制为英文和中文。以肌肉的耐力及收缩力、失神经的肌湿重和骨骼肌的修复情况为评价指标。纳入研究失神经支配骨骼肌萎缩的显微外科手术方法、物理疗法、生物和化学疗法、基因疗法。排除上述方法之外失神经支配骨骼肌萎缩的其他疗法。结果与结论:周围神经损伤后,骨骼肌失神经支配将不可避免的发生萎缩。因此,探索失神经支配骨骼肌萎缩的防治方法,吸引了国内外许多学者的兴趣,必将成为21世纪周围神经领域内的重要任务和研究热点。显微外科手术、物理疗法、生物和化学疗法、基因疗法等都是失神经支配骨骼肌萎缩有效的防治手段。目前,该领域的研究已经呈现多角度、多方面的趋势。失神经肌萎缩的防治方面已经有了针对性的措施,但在改善微循环、防止细胞凋亡、抑制胶原过度生长以及如何应用基因治疗的方法在基因水平改变生肌调节因子的表达等方面,还有大量工作需要进行。随着组织工程学、细胞培养学、分子生物学、基因工程等方面的不断发展,防治失神经肌萎缩必定会有新的突破。     

Cell proliferation in denervated muscle: Identity and origin of dividing cells

DNA synthesis in skeletal muscle increases dramatically during the first week after denervation.¹⁹ In the present study, we have characterized the dividing cells in order to assess the specificity and significance of this response to denervation. Autoradiography of [³H]thymidine-labeled denervated muscles revealed that many classes of cells were dividing, including fibroblasts (the most numerous of the labeled cells), macrophages, vascular cells, muscle satellite cells, spindle capsule cells, perineurial cells and Schwann cells. The number of labeled satellite cells accounted for no more than 10% of the dividing cells. Labeling indices of spindle capsule, perineurial and Schwann cells reached a maximum 3 days after denervation, while those of fibroblasts and macrophages peaked at 4 days. The former group of cells, which are in close contact with nerve trunks, accounted for 28% of cell division on day 3 (but only 5% on day 4) and were apparently responding to a local influence from degenerating axons. Connective tissue cells, making up the largest class of dividing cells (80% on day 4) were found throughout the muscle and appeared to proliferate in response to changes occurring along the entire length of the muscle fibers. Macrophages involved in the response were mostly resident histiocytes, since prior labeling of blood cells showed that leukocytes did not enter the muscle in substantial number after denervation. Both muscle satellite cells and connective tissue cells are essential for the functional regeneration of muscle.⁸ Thus, on the basis of overall cytologic characterization, cell division after denervation seems to represent a limited regenerative response.     

Functional characterization of heterotrimeric G-proteins in rat diaphragm muscle

Seven-transmembrane receptors mediate diverse skeletal muscle responses for a wide variety of stimuli, via activation of heterotrimeric G-proteins. Herein we evaluate the expression and activation of rat diaphragm or cultured skeletal muscle G-proteins using [(35)S]GTPγS. Total membrane Gα subunit content was 4-7 times higher in rat primary cultured myotubes and L6 cell line than in diaphragm (32.6±1.2fmol/mg protein) and 7-27% of them were in the active conformational state. Immunoprecipitation assay showed equal expression of diaphragm Gαs, Gαq and Gαi/o. Addition of GDP allowed the measurement of G-protein activation by different GPCR, including adrenoceptor, adenosine, melatonin and muscarinic receptors. Diaphragm denervation resulted in a marked increase in both total and active state G-protein levels. Together, the results show that [(35)S]GTPγS binding assay is a sensitive and valuable method to evaluate GPCR activity in skeletal muscle cells, which is of particular interest for pharmacological analysis of drugs with potential use in the management of respiratory muscle failure.     

Cell proliferation in denervated muscle: Time course,distribution and relation to disuse

The effects of denervation on skeletal muscle fibers have been intensively investigated, but the effects on other cell types within muscle tissue are not well understood. In the present experiments, cell proliferation was analyzed in mouse extensor digitorum longus muscles denervated for periods of one day to six weeks. Incorporation of tritiated thymidine into DNA increased 36 h after denervation, reached a maximum at a level twenty times control at 4 days, and returned towards control values by 7 days. Incorporation first increased in the endplate area, but 12 h later involved the entire muscle. Six weeks after denervation, muscles labeled at 4 days had lost 90% of the total label. Muscle disuse, produced by tetrodotoxin block of the nerve for up to 4 days, did not result in a proliferative response.Thus, cell proliferation after denervation is not a response to simple disuse, but rather to a nerve- or muscle-related mitogen. Since the response is mostly distributed throughout the entire muscle, the mitogen probably emanates from muscle fibers.     

Developmental regulation of interstitial cell density in bullfrog skeletal muscle

Denervation of skeletal muscle results in striking connective tissue remodelling in junctional areas of muscle. Since extracellular matrix molecules mediate axonal growth and synaptic differentiation, it is likely that the interstitial cells and matrix molecules that accumulate near synaptic sites after denervation influence the regrowth and regeneration of synaptic connections. The experiments presented here addressed the question of whether the junctional connective tissue in developing bullfrog skeletal muscle was also specialized in its cellular and molecular composition. Denervation responses of muscle, such as extrajunctional sensitivity to acetylcholine, often reproduce the characteristics of developing muscle during synaptogenesis. In developing muscle, the distribution of interstitial cells was nonuniform during the period of muscle fibre birth and synaptogenesis. Interstitial cells were concentrated near synaptic sites as in denervated adult muscle. Unlike denervated adult muscle, there were no junctional accumulations of fibronectin or tenascin, matrix molecules produced by interstitial cells, in developing muscles. These results demonstrate that the junctional connective tissue in developing muscle is identified by a high density of interstitial cells that may play a role in the identification and formation of synaptic sites. Further, the junctional matrix environment of developing muscle is distinct from the matrix remodelling that occurs in response to denervation, suggesting that the matrix production by interstitial cells during development is regulated differently from that after denervation of the neuromuscular junction.     

成年大鼠骨骼肌干细胞纯化、培养及移植的初步实验研究

目的探讨成年大鼠骨骼肌干细胞纯化与培养方法及肌干细胞移植在肌疾病治疗中的价值。方法采用混合酶消化及反复差速贴壁法分离、纯化培养SD大鼠骨骼肌干细胞,然后用携带lac-Z基因的腺病毒载体转染肌干细胞,待转染成功后将携带lac-Z基因的骨骼肌干细胞注射于自体和同种异体的膀胱颈及后尿道周围,分别于注射后5、15d,处死大鼠取出膀胱颈及后尿道,行组织学检查及X-gal染色。结果成功地分离、培养了成年大白鼠的骨骼肌干细胞。注射部位无明显炎症改变,经X-gal染色显示自体细胞移植5d及15d均可见大量的蓝染细胞,提示移植细胞在体内成活,异体移植各时间点未见蓝染细胞。结论采用混合酶消化及差速贴壁的方法可以成功纯化骨骼肌干细胞;自体骨骼肌干细胞移植在体内可以存活,有可能成为治疗肌疾病的有效方法,而异体移植不能存活。     

Effects of botulinum toxin induced muscle paralysis on endocytosis and lysosomal enzyme activities in mouse skeletal muscle

The effects of botulinum toxin (type A) induced muscle paralysis on endocytosis and lysosomal enzyme activities in skeletal muscle were compared with the effects of surgical denervation. Muscle atrophy, measured as decrease in total muscle protein content, was as large or larger after botulinum toxin treatment as after denervation. Endocytic activity, measured as the in vitro uptake of horseradish peroxidase, and the specific activities of the lysosomal enzymes N-acetyl--d-glucosaminidase and cathepsin D were all increased six days after denervation. Only the specific activity of cathepsin D was increased six days after botulinum toxin poisoning. The uptake of horseradish peroxidase and the specific activity of N-acetyl--d-glucosamidase were also increased eleven days after poisoning. Transverse sections of eleven days botulinum poisoned muscles from animals injected with horseradish peroxidase showed fibres with dense peroxidase staining similar to those seen in denervated muscle although they seemed to occur less frequently.The results show that increases in endocytic activity and lysosomal enzyme activities may occur in skeletal muscle without the presence of degenerating axons. The differences in effects of surgical denervation and botulinum toxin induced paralysis are discussed in terms of what is known about the mechanism of action of botulinum toxin and the possible functional roles of the two lysosomal enzymes studied.     

P2X7 activation enhances skeletal muscle metabolism and regeneration in SOD1G93A mouse model of amyotrophic lateral sclerosis

Muscle weakness plays an important role in neuromuscular disorders comprising amyotrophic lateral sclerosis (ALS). However, it is not established whether muscle denervation originates from the motor neurons, the muscles or more likely both. Previous studies have shown that the expression of the SOD1G93A mutation in skeletal muscles causes denervation of the neuromuscular junctions, inability to regenerate and consequent atrophy, all clear symptoms of ALS. In this work, we used SOD1G93A mice, a model that best mimics some pathological features of both familial and sporadic ALS, and we investigated some biological effects induced by the activation of the P2X7 receptor in the skeletal muscles. The P2X7, belonging to the ionotropic family of purinergic receptors for extracellular ATP, is abundantly expressed in the healthy skeletal muscles, where it controls cell duplication, differentiation, regeneration or death. In particular, we evaluated whether an in vivo treatment in SOD1G93A mice with the P2X7 specific agonist 2′(3′)‐O‐(4‐Benzoylbenzoyl) adenosine5′‐triphosphate (BzATP) just before the onset of a pathological neuromuscular phenotype could exert beneficial effects in the skeletal muscles. Our findings indicate that stimulation of P2X7 improves the innervation and metabolism of myofibers, moreover elicits the proliferation/differentiation of satellite cells, thus preventing the denervation atrophy of skeletal muscles in SOD1G93A mice. Overall, this study suggests that a P2X7‐targeted and site‐specific modulation might be a strategy to interfere with the complex multifactorial and multisystem nature of ALS.     

Nerve dependent regulation of neural cell adhesion molecule expression in skeletal muscle

The expression of neural cell adhesion molecule was analysed by indirect immunofluorescence on adult mouse skeletal muscle subjected to a variety of experimental lesions. Adult mouse muscle does not express neural cell adhesion molecule at the sarcolemma. However, following denervation there is a rapid rise in neural cell adhesion molecule levels; this is initially in the cytoplasm of the myofibres but by 18 days there is intense reactivity at the sarcolemma. A nerve crush lesion was used to show that the increase in neural cell adhesion molecule levels following denervation is accompanied by a switch-off of neural cell adhesion molecule expression following reinnervation. Paralysis of skeletal muscle by botulinum toxin injection is sufficient to activate neural cell adhesion molecule expression. As paralysis of skeletal muscle by botulinum toxin is not accompanied by activation of muscle satellite cells or degeneration products of nerve or myelin, it suggests that the observed levels of neural cell adhesion molecule are synthesised by myofibres. As the expression of neural cell adhesion molecule in these lesions parallels the ability of skeletal muscle to accept innervation it is possible that neural cell adhesion molecule acts as a molecular cue at the sarcolemma in regulating synaptogenesis.     

Expression of myostatin RNA transcript and protein in gastrocnemius muscle of rats after sciatic nerve resection

Myostatin, a member of the transforming growth factor-beta (TGF-beta) superfamily, has been identified as an inhibitor of skeletal muscle mass. To have an insight into the expression pattern of myostatin and its potential role in skeletal muscle atrophy induced by denervation, we used an animal model of peripheral nerve resection to examine the time-dependent changes in myostatin mRNA and protein levels in the denervated gastrocnemius muscle of rats after sciatic neurectomy by the aid of quantitative real-time RT-PCR and Western blotting, respectively. We also conducted morphometric analyses to measure the wet weight ratio of the denervated muscle (the operated side/contralateral non-operated side) and the cross sectional area of muscle fibers and to observe muscle morphology. The experimental results showed that myostatin mRNA and protein levels in rat gastrocnemius muscle persistently elevated after denervation, despite a fluctuation of myostatin mRNA level at day 3 after denervation, reached their respective peaks at day 28 after denervation, and then depressed slightly until day 56 after denervation. Furthermore, a significant negative linear correlation was found between myostatin abundance and muscle atrophy degree, suggesting that myostatin might probably play an important role in denervation-induced muscle atrophy. Our present study perhaps provides a new window into myostatin regulation in association with a specific type of muscle atrophy.