运动诱导的骨骼肌信号机制

背景：运动可通过增强骨骼肌葡萄糖转运及胰岛素活动,来调节葡萄糖内环境。明确这些复杂过程的分子机制将无疑为治疗提供更多的靶向,也为认识这些复杂的生理过程提供最基本的知识。目的：综述运动诱导骨骼肌葡萄糖转运的分子信号机制。方法：以＂骨骼肌,运动,腺苷酸活化蛋白激酶,葡萄糖摄取,葡萄糖运载体4＂为中文检索词,以＂skeletal muscle,exercise,AMPK,glucose uptake,GLUT4＂为英文检索词。应用计算机检索PubMed数据库和中文期刊全文数据库2011年11月前发表有关运动诱导骨骼肌信号机制的研究文献,排除重复性研究及Meta分析类文章。共保留39篇文献进行综述。结果与结论：运动/收缩和胰岛素是骨骼肌葡萄糖转运的最有效的和生理相关的刺激,运动诱导的信号机制代表着糖尿病治疗药物学靶点发展的一个重要步骤。运动是通过增加骨骼肌葡萄糖摄取来改善葡萄糖内环境的,而运动诱导的葡萄糖摄取是有多种信号途径来介导的,包括腺苷酸活化蛋白激酶、非典型蛋白激酶C、钙调节依赖蛋白激酶及相对分子质量为160000的Akt底物等。这些骨骼肌信号机制通过刺激葡萄糖运载体4活动增加来调节葡萄糖的转运。     

骨骼肌细胞葡萄糖运载体4的研究进展

骨骼肌是体内最主要摄取葡萄糖和代谢葡萄糖的组织之一。葡萄糖跨膜转运是骨骼肌利用葡萄糖的首要步骤。葡萄糖跨膜进入骨骼肌细胞需要细胞膜上的葡萄糖运载体（glucose transporter,GLUT）协助扩散。GLUT有多种亚型，其中葡萄糖运载体4（GLUT4）是存在于骨骼肌、脂肪组织中帮助葡萄糖转运的蛋白。胰岛素和肌肉收缩可通过不同的机制调节GLUT4的基因表达和转位，从而促进葡萄糖的跨膜转运。因此，GLUT4是糖尿病基础研究中的一个热点。     

葡萄糖运载体4

胰岛素抵抗是２型糖尿病患者糖利用障碍的主要原因之一。研究发现胰岛素受体后缺陷在胰岛素抵抗的环节中,意义尤为突出,其中外周组织,主要是骨骼肌和脂肪组织对葡萄糖摄取、利用减少是受体后胰岛素抵抗的主要原因。而葡萄糖的跨膜转运是骨骼肌细胞利用葡萄糖的主要限速步骤。目前研究表明,这一过程是依靠细胞膜上的特殊转运蛋白来完成的,这种特殊转运蛋白称为葡萄糖运载体（ｇｌｕｃｏｓｅｔｒａｎｓｐｏｒｔｅｒ,ＧＬＵＴ）。骨骼肌细胞中存在两种ＧＬＵＴ,分别为ＧＬＵＴ１和ＧＬＵＴ４,前者主要位于骨骼肌细胞外膜上,只在基础状…     

运动诱导甘丙肽分泌对2型糖尿病大鼠胰岛素敏感性的影响

目的：探讨运动后甘丙肽(GAL)分泌增加对2型糖尿病大鼠大鼠胰岛素敏感性的影响。方法：糖尿病大鼠随机分4组：安静对照组、运动对照组、安静用药组、运动用药组。安静对照组及运动对照组均腹腔注射生理盐水,安静用药组及运动用药组腹腔注射GAL。快速血糖仪测空腹血糖以计算胰岛素抵抗指数,Western Blot 法检测骨骼肌葡萄糖转运蛋白4（GLUT4）含量。结果：运动对照组与安静对照组以及运动用药组与安静用药组相比较,正糖钳的葡萄糖输注速率显著性增加（P<0.05）;安静用药组及运动用药组实验后比实验前血清胰岛素均显著增加（P<0.05）,安静用药组实验后比实验前胰岛素敏感指数有非常显著下降（P<0.01）;运动对照组比安静对照组骨骼肌GLUT4蛋白含量非常显著性提高（P<0.01）,运动用药组比安静用药组GLUT4蛋白含量显著性提高（P<0.05）。结论：运动诱导GAL浓度增加,可能主要依靠增加GLUT4膜转运量或提高GLUT4活性来提高胰岛素敏感性。     

运动对糖尿病大鼠骨骼肌细胞葡萄糖运载体4转位机制的影响

目的　研究运动对链脲佐菌素 (STZ)引起的糖尿病大鼠骨骼肌细胞葡萄糖运载体 4(Glucosetransporter 4,GLUT4)转位机制的影响。 方法　将实验大鼠分为 3组 :正常对照组、糖尿病组和糖尿病运动组。糖尿病运动组大鼠进行 6周游泳训练。实验到期分离各组大鼠大腿股四头肌 ,制备细胞内、外膜 ,以Western印迹法检测GLUT4蛋白含量 ,同时检测大鼠血清胰岛素和血糖浓度。结果　糖尿病大鼠骨骼肌细胞GLUT4蛋白含量明显减少 ,与正常对照组相比 ,细胞内膜GLUT4蛋白含量减少 2 4.1% (P <0 .0 1) ,细胞外膜减少 48.1% ,(P <0 .0 1)。糖尿病大鼠经过 6周运动训练 ,与糖尿病组大鼠相比 ,骨骼肌细胞内膜GLUT4蛋白含量无明显变化 ,而细胞外膜GLUT4蛋白含量增加 10 8.7% (P <0 .0 1) ,血糖由18.5± 1.9mmol/L降至 14 .0± 3 .3mmol/L(P <0 .0 1)。结论　糖尿病状态下骨骼肌细胞GLUT4蛋白含量明显减少 ,其中以细胞外膜GLUT4蛋白含量的减少更为显著 ,即在糖尿病状态下骨骼肌细胞GLUT4蛋白转位机制出现障碍 ,使肌细胞对葡萄糖的转运发生障碍 ,血糖升高。糖尿病大鼠经过运动训练可增加骨骼肌细胞GLUT4蛋白含量 ,并改善GLUT4蛋白转位机制 ,从而增加肌细胞对葡萄糖的转运和利用 ,降低血糖 ,改善糖尿病大鼠糖代谢紊乱的状况。     

运动对葡萄糖转运蛋白4介导的骨骼肌糖摄取调节机制的研究进展

<正>葡萄糖转运蛋白4(glucose transporter 4,Glut4)是骨骼肌细胞中主要的葡萄糖转运载体[1],它所介导的葡萄糖转运是骨骼肌糖代谢的主要限速步骤[2]。大量研究发现,Glut4的紊乱将导致骨骼肌对葡萄糖的摄取、利用减少,而骨骼肌是全身葡萄糖利用最主要的组织,约占整个葡萄糖转运的80%。目前研究表明,Glut4调节紊乱是糖尿病发病的主要原因之一。     

微载体培养技术在骨与软骨组织工程研究中的应用

背景：骨与软骨组织工程学中增殖种子细胞和保持细胞特定表型是其难点,微载体生物反应器培养系统提供了很好的条件来解决这个问题。目的：分析近年来国内外骨、软骨细胞微载体培养的研究进展,为骨与软骨细胞微载体培养技术和组织工程研究提供理论基础。方法：由第一作者在2010-11进行检索。检索数据库：PubMed数据库（网址http：//www.ncbi.nlm.gov/PubMed）;万方数据库（网址http：//www.wanfangdata.com.cn）,资料的检索时间范围为1967/2011。英文检索词为＂microcarrier,cartilage,tissue engineering＂,中文检索词为＂微载体,软骨,组织工程学＂。排除与本文无关及陈旧、重复的文章,共保存32篇文献做进一步分析。结果与结论：在微载体培养系统中,可较好的调控骨与软骨细胞培养条件,能在短时间内大量的增殖,并能保持其细胞的表型,甚至出现表型增强现象,在骨、软骨组织工程学研究和临床应用中有着巨大潜力。     

髓内钉和微创钢板在肱骨干骨折内固定治疗中的应用

背景：随着微创技术的开展,髓内钉和微创钢板内固定广泛应用于肱骨干骨折并取得良好效果,但也并存一些并发症,如何改进内固定的设计及操作以减少或避免并发症成为研究热点。目的：总结近年来肱骨干骨折微创内固定的治疗进展。方法：由第一作者检索PubMed/MEDLINE（http：//www.ncbi.nlm.nih.gov/PubMed）、Webofknowledge（http：//apps.isiknowledge.com）、OVID（http：//ovidsp.tx.ovid.com）、Elsevier（http：//www.sciencedirect.com）、中国期刊网（http：//epub.edu.cnki.net）及万方数据库（http：//wanfang.lib.sjtu.edu.cn）2005/2010有关髓内钉和微创钢板内固定治疗肱骨干骨折的文献,英文检索词为＂humeralshaftfractures,internalfixation,minimallyInvasvie＂,中文检索词为＂肱骨干骨折,微创,内固定＂。排除重复性研究及肱骨干病理性骨折相关文献,纳入32篇文献进行综述。结果与结论：只有准确掌握肱骨干骨折及不同内固定种类的特点,做到个体化治疗,才能达到最好的治疗效果并最大程度减少并发症。目前深化了对肩袖损伤的认识,初步寻找到减少肩袖损伤的方法,改进了髓内钉及钢板的设计,在方便操作、减少手术时间的同时一定程度上避免了神经血管损伤。     

运动训练对老年大鼠肌细胞葡萄糖转运蛋白的影响

目前研究表明 ,随年龄增加葡萄糖耐量逐渐降低。这种与年龄相关的葡萄糖耐量降低被认为是由于外周组织对胰岛素的抵抗[1] 。在外周组织中 ,骨骼肌是胰岛素促进葡萄糖利用的最主要部位 ,如果骨骼肌对葡萄糖的利用率下降可表现明显的胰岛素抵抗。研究发现 ,骨骼肌细胞摄取葡萄糖主要依靠细胞膜上的葡萄糖转运蛋白 (ｇｌｕｃｏｓｅｔｒａｎｓｐｏｒｔｅｒ ,ＧＬＵＴ) ,其中ＧＬＵＴ4是骨骼肌最主要的转运蛋白 ,它的含量多少决定了骨骼肌利用葡萄糖的速率。本研究的目的是观察老年大鼠骨骼肌ＧＬＵＴ4含量的变化 ,以及运动训练对老年大鼠骨骼肌…     

运动中NO信号传递途径及其对骨骼肌摄取葡萄糖的调节

学术背景:NO能影响葡镛糖的转运,虽然其信号传递途径与具体机制不明了,但已确认其与胰岛素介导途径不同.目的:探讨运动中NO信号传递途径及其对骨骼肌摄取葡萄糖的调节机制.检索策略:由第一作者检索Pubmed(布尔逻辑)1996-0112007-11收录的运动中NO信号传导及其调节肌肉摄取葡萄糖相关文章,检索词"(nitric oxide AND signal AND glucose)NOT patient";并由第二作者手工检索国家图书馆外文库(中图法分类)相关书籍.纳入标准:人和啮齿动物在运动应激情况下NO调节肌肉血流量、信号传递和调节葡萄糖相关文献;排除标准:病理条件下相关基础研究.文献评价:共检索到60篇相关文献(书籍),30篇符合标准.其中5篇是综述类文献,23篇为基础研究,2本相关专业书籍.其中20篇关于NO的调节血流量和舒血管作用,4篇文献和2本书籍关于信号传导,4篇涉及NO为运动中信号分子.资料综合:NO有强烈舒血管作用,是细胞间信使分子,能介导许多生物现象.运动时体内NO生成增多,NO通过在骨骼肌内的传导能刺激肌肉摄取葡萄糖.结论:运动中NO大量生成对骨骼肌摄取葡萄糖有积极影响,肌肉收缩和摄取葡萄糖与NO的生成、传递联系密切,但其机制尚不明了.     

白细胞介素6对2型糖尿病大鼠骨骼肌糖代谢的影响

目的：通过研究白细胞介素6（IL－6）对2型糖尿病（T2DM）大鼠骨骼肌葡萄糖转运体4（GLUT4）和糖原含量的影响,探讨其影响T2DM糖代谢的机制。方法：健康雄性SD大鼠随机分为4组：正常对照组（N组）10只,糖尿病IL-6抗原干预组（A组）10只,糖尿病IL－6抗体干预组（B组）8只,糖尿病对照组（C组）8只。测定血糖、血清胰岛素、血脂等指标;取股四头肌比色法测定肌糖原含量,免疫组化法测定骨骼肌GLUT4蛋白表达。结果：T2DM大鼠骨骼肌糖原含量和GLUT4蛋白表达较正常大鼠明显降低,IL-6抗体干预可以升高T2DM大鼠骨骼肌糖原含量和GLUT4蛋白表达。结论：T2DM大鼠骨骼肌GLUT4蛋白表达减少;IL－6抗体阻滞通过增加GLUT4蛋白表达促进骨骼肌对糖的利用。     

L6大鼠成肌细胞胰岛素信号传导通路中磷脂酰肌醇3激酶、蛋白激酶B和葡萄糖转运蛋白4的表达

背景：血管紧张素Ⅱ可损伤胰岛素信号中的下游信号分子引起胰岛素抵抗,但其机制不清。目的：观察血管紧张素Ⅱ对L6大鼠成肌细胞胰岛素信号传导通路中磷脂酰肌醇3激酶、蛋白激酶B和葡萄糖转运蛋白4的影响。方法：L6细胞培养及诱导分化肌管,根据干预措施不同实验分为对照组、胰岛素组、胰岛素＋血管紧张素Ⅱ组及胰岛素＋血管紧张素Ⅱ＋H89组。采用RT-PCR检测4组磷脂酰肌醇3激酶、蛋白激酶B mRNA表达,免疫荧光检测胰岛素受体底物1、酪氨酸磷酸化胰岛素受体底物1、葡萄糖转运蛋白4表达。结果与结论：胰岛素组、胰岛素＋血管紧张素Ⅱ组及胰岛素＋血管紧张素Ⅱ＋H89组的磷脂酰肌醇3激酶mRNA表达均较对照组显著升高（P〈0.05）。各组间蛋白激酶B mRNA表达差异无显著性意义（P〉0.05）。相比对照组,其余3组间胰岛素受体底物1、酪氨酸磷酸化胰岛素受体底物1和葡萄糖转运蛋白4（膜蛋白）表达均升高（P〈0.05）;胰岛素＋血管紧张素Ⅱ＋H89组酪氨酸磷酸化胰岛素受体底物1和葡萄糖转运蛋白4表达低于胰岛素组但高于胰岛素＋血管紧张素Ⅱ组（P〈0.05）。结果显示,血管紧张素Ⅱ在骨骼肌细胞中通过JAK2-PKA通路引起胰岛素下游信号传导受阻,葡萄糖转运蛋白4表达减少,葡萄糖转运障碍,进而导致胰岛素抵抗。     

多囊卵巢综合征骨骼肌胰岛素抵抗大鼠模型的建立

背景：研究表明胰岛素抵抗在多囊卵巢综合征的发生与发展过程中起重要作用,建立理想的多囊卵巢综合征骨骼肌胰岛素抵抗动物模型是研究该疾病的基础。目的：探讨建立较为理想的多囊卵巢综合征骨骼肌胰岛素抵抗大鼠模型的方法。方法：将八九周龄SD雌性大鼠随机分为模型组和对照组。模型组给予胰岛素联合人绒毛膜促性腺激素皮下注射,并以高脂饲料和50g/L葡萄糖水喂养,对照组皮下注射生理盐水,常规饮食喂养。结果与结论：造模6周后,模型组大鼠卵巢体积明显增大,且呈多囊性改变;血清睾酮、黄体生成素、空腹血糖和胰岛素水平高于对照组;骨骼肌组织中葡萄糖转运蛋白4表达明显低于对照组,且其葡萄糖转运蛋白4阳性颗粒靠近骨骼肌细胞膜边缘者较少。可见胰岛素联合人绒毛膜促性腺激素皮下注射,并饲以高脂饲料和50g/L葡萄糖水是建立多囊卵巢综合征骨骼肌胰岛素抵抗大鼠模型较为理想的方法。     

Effect of diabetes on glucoregulation. From glucose transporters to glucose metabolism in vivo.

Peripheral resistance to insulin is a prominent feature of both insulin-dependent and non-insulin-dependent diabetes. Skeletal muscle is the primary site responsible for decreased insulin-induced glucose utilization in diabetic subjects. Glucose transport is the rate-limiting step for glucose utilization in muscle, and that cellular process is defective in human and animal diabetes. The transport of glucose across the muscle cell plasma membrane is mediated by glucose transporter proteins, and two isoforms (GLUT1 and GLUT4) are expressed in muscle. Insulin acutely increases glucose transport in muscle by selectively stimulating the recruitment of the GLUT4 transporter (but not GLUT1) from an intracellular pool to the plasma membrane. In skeletal muscles of streptozocin-induced diabetic rats, there is a decreased GLUT4 protein content in intracellular and plasma membranes. In these rats, insulin induced the mobilization of GLUT4 from the internal pool, but the incorporation of the transporter protein into the plasma membrane is diminished. Conversely, the content of the GLUT1 transporter increases in the plasma membrane of these diabetic rats. Normalization of glycemia with phlorizin fully restores the amount of GLUT1 and GLUT4 proteins to normal levels in the plasma membrane without altering insulin levels. This suggests that glycemia regulates the number of glucose transporters at the cell surface, GLUT1 varying directly and GLUT4 inversely, to glycemia. The regulatory role of glycemia also can be seen in diabetic dogs in vivo, where correction of hyperglycemia with phlorizin restores, at least in part, the defective metabolic clearance rate of glucose seen in these animals. In addition to acutely stimulating glucose transport in muscle, insulin controls exercise- and possibly stress-mediated glucose uptake in vivo, by preventing hyperglycemia and by restraining the effects of catecholamines on lipolysis and/or muscle glycogenolysis. Finally, we postulated a neural pathway that requires the permissive effect of insulin to increase glucose uptake by the muscle. Thus, insulin, glucose, and neural pathways regulate muscle glucose utilization in vivo and are, therefore, important determinants of glucoregulation in diabetes.     

Islet transplantation under the kidney capsule fully corrects the impaired skeletal muscle glucose transport system of streptozocin diabetic rats.

Chronic insulin therapy improves but does not restore impaired insulin-mediated muscle glucose uptake in human diabetes or muscle glucose uptake, transport, and transporter translocation in streptozocin diabetic rats. To determine whether this inability is due to inadequate insulin replacement, we studied fasted streptozocin-induced diabetic Lewis rats either untreated or after islet transplantation under the kidney capsule. Plasma glucose was increased in untreated diabetics and normalized by the islet transplantation (110 +/- 5, 452 +/- 9, and 102 +/- 3 mg/dl in controls, untreated diabetics, and transplanted diabetics, respectively). Plasma membrane and intracellular microsomal membrane vesicles were prepared from hindlimb skeletal muscle of basal and maximally insulin-stimulated rats. Islet transplantation normalized plasma membrane carrier-mediated glucose transport Vmax, plasma membrane glucose transporter content, and insulin-induced transporter translocation. There were no differences in transporter intrinsic activity (Vmax/Ro) among the three groups. Microsomal membrane GLUT4 content was reduced by 30% in untreated diabetic rats and normal in transplanted diabetics, whereas the insulin-induced changes in microsomal membrane GLUT4 content were quantitatively similar in the three groups. There were no differences in plasma membrane GLUT1 among the groups and between basal and insulin stimulated states. Microsomal membrane GLUT1 content was increased 60% in untreated diabetics and normalized by the transplantation. In conclusion, an adequate insulin delivery in the peripheral circulation, obtained by islet transplantation, fully restores the muscle glucose transport system to normal in streptozocin diabetic rats.     

Insulin resistance in obese Zucker rat (fa/fa) skeletal muscle is associated with a failure of glucose transporter translocation.

The genetically obese Zucker rat (fa/fa) is characterized by a severe resistance to the action of insulin to stimulate skeletal muscle glucose transport. The goal of the present study was to identify whether the defect associated with this insulin resistance involves an alteration of transporter translocation and/or transporter activity. Various components of the muscle glucose transport system were investigated in plasma membranes isolated from basal or maximally insulin-treated skeletal muscle of lean and obese Zucker rats. Measurements of D- and L-glucose uptake by membrane vesicles under equilibrium exchange conditions indicated that insulin treatment resulted in a four-fold increase in the Vmax for carrier-mediated transport for lean animals [from 4.5 to 17.5 nmol/(mg.s)] but only a 2.5-fold increase for obese rats [from 3.6 to 9.1 nmol/(mg.s)]. In the lean animals, this increase in glucose transport function was associated with a 1.8-fold increase in the transporter number as indicated by cytochalasin B binding, a 1.4-fold increase in plasma membrane GLUT4 protein, and a doubling of the average carrier turnover number (intrinsic activity). In the obese animals, there was no change in plasma membrane transporter number measured by cytochalasin B binding, or in GLUT4 or GLUT1 protein. However, there was an increase in carrier turnover number similar to that seen in the lean litter mates. Measurements of GLUT4 mRNA in red gastrocnemius muscle showed no difference between lean and obese rats. We conclude that the insulin resistance of the obese rats involves the failure of translocation of transporters, while the action of insulin to increase the average carrier turnover number is normal.     

Calcium channel blocker azelnidipine reduces glucose intolerance in diabetic mice via different mechanism than angiotensin receptor blocker olmesartan

The potential combined effect and mechanism of calcium channel blockers (CCB) and angiotensin II type 1 receptor blockers (ARB) to improve insulin resistance were investigated in type 2 diabetic KK-Ay mice, focusing on their antioxidative action. Treatment of KK-Ay mice with a CCB, azelnidipine (3 mg/kg/day), or with an ARB, olmesartan (3 mg/kg/day), for 2 weeks lowered the plasma concentrations of glucose and insulin in the fed state, attenuated the increase in plasma glucose in the oral glucose tolerance test (OGTT), and increased 2-[(3)H]deoxy-d-glucose (2-[(3)H]DG) uptake into skeletal muscle with the increase in translocation of glucose transporter 4 (GLUT4) to the plasma membrane. Both blockers also decreased the in situ superoxide production in skeletal muscle. The decrease in plasma concentrations of glucose and insulin in the fed state and superoxide production in skeletal muscle, as well as GLUT4 translocation to the plasma membrane, after azelnidipine administration was not significantly affected by coadministration of an antioxidant, 2,2,6,6-tetramethyl-1-piperidinyloxy (tempol). However, those changes caused by olmesartan were further improved by tempol. Moreover, olmesartan enhanced the insulin-induced tyrosine phosphorylation of insulin receptor substrate-1 induced in skeletal muscle, whereas azelnidipine did not change it. Coadministration of azelnidipine and olmesartan further decreased the plasma concentrations of glucose and insulin, improved OGTT, and increased 2-[(3)H]DG uptake in skeletal muscle. These results suggest that azelnidipine improved glucose intolerance mainly through inhibition of oxidative stress and enhanced the inhibitory effects of olmesartan on glucose intolerance, as well as the clinical possibility that the combination of CCB and ARB could be more effective than monotherapy in the treatment of insulin resistance.     

Coordinate regulation of glucose transporter function, number, and gene expression by insulin and sulfonylureas in L6 rat skeletal muscle cells.

The extrapancreatic actions of sulfonylureas on the glucose transport system were studied in the L6 line of cultured rat skeletal muscle cells. Insulin (10(-7) M) increased 2-deoxyglucose uptake in differentiated L6 myotubes by 30-40% after 8 h of incubation. The sulfonylurea tolazamide (0.6 mg/ml, 22 h) had no effect on glucose uptake in the absence of insulin, but increased insulin-stimulated 2-deoxyglucose uptake twofold. The total cellular content of glucose transporters was assessed with a monoclonal anti-transporter antibody by a solid-phase ELISA method. Insulin (8 h) increased the quantity of glucose transporters, with a maximal twofold increase at 10(-7) M and a dose-response curve similar to that for insulin stimulation of glucose uptake. In spite of its lack of effect on glucose uptake, tolazamide alone (0.6 mg/ml) increased the cellular content of transporters by 70%. The effects of insulin and tolazamide on transporter gene expression were studied with probes derived from Hep G2 glucose transporter cDNA. Insulin increased the transporter mRNA level 1.7-fold, tolazamide increased it 1.5-fold, and the combination of insulin and tolazamide increased transporter mRNA 3-fold. It is concluded that sulfonylureas, together with insulin, enhance glucose uptake in L6 skeletal muscle cells by increasing the number of functioning glucose transport molecules. The long-term regulation of the glucose transport system in skeletal muscle by insulin and sulfonylureas in vivo may involve similar changes in transporter function, number, and gene expression.