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。     

GLUT4转位和活性的研究进展

胰岛素抵抗,即组织对胰岛素反应能力的损害,一直被认为是造成糖耐量受损导致糖尿病的主要原因。造成胰岛素抵抗的机制至今尚不清楚,可能与胰岛素受体后的信号传导缺陷有关。骨骼肌是利用葡萄糖和维持血糖平衡的重要组织,约80%的胰岛素刺激所致葡萄糖摄取是由骨骼肌完成的。GLUT4介导的葡萄糖的转运是骨骼肌的糖代谢的主要限速步骤。研究显示小鼠GLUT4表达失常导致了胰岛素抵抗[1],在DB/DB大鼠模型中GLUT4过多表达可以明显改善糖尿病症状[2]。因此GLUT4的研究对于揭示糖尿病的发病机制,制订糖尿病运动处方有着非常重要的指导意义。目…     

不同强度的耐力运动对糖尿病大鼠骨骼肌 GLUT4 mRNA表达的影响

目的探讨不同强度的耐力运动对糖尿病大鼠骨骼肌GLUT4 mRNA表达的影响.方法雄性SD大鼠,其中36只大鼠经尾静脉注射链脲霉素,建立糖尿病模型.然后随机分为低强度运动组(EL)、高强度运动组(EH)、低强度运动加胰岛素治疗组(LI)、高强度运动加胰岛素治疗组(HI)、胰岛素治疗非运动组(DI)和非胰岛素治疗非运动组(DM).6只SD大鼠为非运动正常血糖组(CN).耐力训练采用活动平板,胰岛素采用皮下注射,共8周.运用RT-PCR法测定骨骼肌GLUT4 mRNA.结果DM组骨骼肌GLUT4 mRNA表达水平显著低于其它各组(P＜0.05).LI组骨骼肌GLUT4 mRNA表达水平明显增高接近CN组,并且显著高于DI组.DI组GLUT4 mRNA含量与EL、EH、HI各组相当,差异无显著性意义.结论运动可以促进GLUT4 mRNA的表达,而运动强度对GLUT4 mRNA表达量无显著影响;低强度运动加胰岛素所具有最佳的GLUT4 mRNA表达水平是其它单独干预措施所无法替代的.     

胰岛素与硒联合作用糖尿病大鼠骨骼肌胰岛素信号转导通路中PI3K和GLUT4蛋白的表达

背景:PI3K是骨骼肌中胰岛素信号转导途径级联反应中关键的蛋白分子之一,其表达异常可影响GLUT4的合成、分泌、移位等变化,从而使血糖升高.目的:通过检测胰岛素和硒联合应用对糖尿病大鼠骨骼肌胰岛素信号转导通路有关蛋白激酶(PI3K、GLUT4)表达的影响.方法:SD雄性大鼠随机分为正常组、糖尿病组、糖尿病+胰岛素组、糖尿病+亚硒酸钠组、糖尿病+胰岛素+亚硒酸钠组.除正常组外,其余4组大鼠腹腔注射链尿佐菌素50 mg/kg复制大鼠糖尿病模型.正常组和糖尿病自由进水和进食;糖尿病+胰岛索组按1 U/(kg·d)皮下注射胰岛素,糖尿病+亚硒酸钠组按180 μg/(kg·d)管饲亚硒酸钠,糖尿病+胰岛素+亚硒酸钠组两药联合用药持续4周;应用免疫印迹和免疫组织化学法检测各实验组骨骼肌胞浆中PI3K和胞膜上GLUT4蛋白表达.结果与结论:免疫组织化学方法所得结果与免疫印迹一致.胰岛索和硒联合应用能明显增加骨骼肌细胞胞浆中PI3K和胞膜上GLUT4蛋白的表达量,说明胰岛索和硒联合应用是通过PI3K途径和增加骨骼肌组织GLUT4蛋白的表达来增强胰岛素信号转导.     

耐力运动对2型糖尿病大鼠骨骼肌葡萄糖运载体4基因表达的影响

目的：探讨耐力运动对糖尿病大鼠骨骼肌葡萄糖运载体4（glucose transporter 4，GLUT4）mRNA表达的影响。方法：32只雄性2型糖尿病OLETF大鼠和13只雄性对照LETO大鼠随机分为6组：A1组OLETF运动组、A2组OLETF运动＋胰岛素组、B1组OLETF非运动组、B2组OLETF非运动＋胰岛素组、C组LETO运动组、D组LETO非运动组。A1、A2、C组参照Ploug报道的大鼠游泳运动方法运动12周。A2、B2组经肝门静脉予胰岛素10U／Kg的注射，1min后处死取材。Real—time PCR方法测定GLUT4 mRNA。结果：GLUT4 mRNA表达在A1组比B1组升高3倍．A2组比A1组升高13倍，B2组比B1组升高20倍，差异均有显著性意义；A2组比B2组GLUT4 mRNA升高2倍，差异无显著性意义。结论：耐力运动可以促进GLUT4 mRNA的表达，耐力运动和胰岛素对糖尿病治疗具有协同作用，两者不能相互替代。     

小牛血清去蛋白注射液对2型糖尿病大鼠糖耐量及骨骼肌GLUT4mRNA表达的影响——附90例报告

目的：探讨小牛血清去蛋白注射液（deproteinized calf serum injection,DCSI）对2型糖尿病模型大鼠的糖耐量及骨骼肌的葡萄糖转运子4（glucose transporter4,GLUT4）mRNA表达的影响。方法：将90只3月龄健康远交系大鼠随机分为6组,每组15只。分别制作正常对照组（正常组）、糖尿病对照组（糖尿病组）、罗格列酮对照组（罗格列酮组）、DCSI高剂量组（高剂量组）、DCSI中等剂量组（中等剂量组）、DCSI低剂量组（低剂量组）等6组模型。在给药4周后行葡萄糖耐量试验,分别测定6组餐后0min、30min、1h、2h的血糖水平;次日处死小鼠,采用逆转录PCR法检测6组大鼠模型骨骼肌中GLUT4mRNA的相对表达量。结果：糖尿病组、低剂量组、中等剂量组、高剂量组、罗格列酮各时间段的血糖水平均高于正常组（均为P〈0．01）。低剂量组、中等剂量组、高剂量组和罗格列酮组的各时间段的血糖水平均明显低于糖尿病组（均为P〈0．01）。上述4组治疗组中,低剂量组、高剂量组餐后1h、餐后2h的血糖水平均高于罗格列酮组（均为P〈0．05）,中等剂量组餐后1h、餐后2h的血糖水平与罗格列酮组比较差异则无统计学意义（均为P〉0．05）。另外,糖尿病组的骨骼肌GLUT4mRNA的相对表达量明显低于正常组。罗格列酮组、低剂量组、中等剂量组及高剂量组GLUT4mRNA的相对表达量明显高于糖尿病组。上述4组治疗组中,中等剂量组GLUT4mRNA的相对表达量最高,接近于正常组。结论：DCSI尤其是中等剂量的DCSI可改善2型糖尿病模型大鼠的糖耐量,使其骨骼肌的GLUT4mRNA表达量增加。     

电针治疗对胰岛素抵抗大鼠骨骼肌葡萄糖转运蛋白4及蛋白激酶BβmRNA表达的影响

目的观察电针对胰岛素抵抗（IR）大鼠胰岛素信号转导途径中葡萄糖转运蛋白4(GLUT4)及蛋白激酶Bβ（Akt2）表达的影响。 方法共选取24只健康Wistar雄性大鼠,采用随机数字表法将其分为正常对照组、模型组及电针组,每组8只。采用高脂膳食喂养将模型组及电针组大鼠制成IR模型,电针组于制模成功后给予电针背俞穴治疗。于电针治疗2周后检测各组大鼠胰岛素敏感性指数（ISI）;选用逆转录聚合酶链反应（RT-PCR）对各组大鼠骨骼肌细胞GLUT4及Akt2 mRNA表达进行定量分析。 结果模型组大鼠血浆胰岛素（FINS）较正常对照组明显升高（P<0.05）,ISI较正常对照组显著降低（P<0.05）;电针组大鼠经电针治疗2周后,发现其FINS较模型组明显降低（P<0.05）,ISI则显著升高（P<0.05）;并且电针组骨骼肌细胞中GLUT4及Akt2 mRNA表达均显著强于模型组水平（P<0.05）。 结论电针治疗能改善IR模型大鼠病情,其治疗机制可能与电针促进胰岛素磷脂酰肌醇-3激酶途径通路中GLUT4转位有关。     

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。     

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。     

肥胖者网膜脂肪组织中叉头状转录因子O1、葡萄糖转运体4mRNA的表达及其与胰岛素抵抗相关性的研究

目的观察肥胖者网膜脂肪组织中叉头状转录因子O1（FOXO1）、葡萄糖转运体4（GLUT4）mRNA表达,探讨FOXO1在肥胖和胰岛素抵抗发生中的作用。方法聚集15例肥胖者和17例非肥胖者的网膜脂肪组织应用半定量反转录聚合酶链反应（RT—PCR）测定FOXO1、GLUT4mRNA表达,并测定其他临床指标,分析各指标之间的相关性及与胰岛素敏感性的关系。结果肥胖者FOXO1 mRNA的表达显著高于非肥胖对照组,（0．577±0．038VS0．359±0．023）（P〈0．01）,GLUT4mRNA的表达明显低于非肥胖对照组,（0．386±0．037VS0．646±0．034）（P〈0．01）;网膜脂肪组织FOXO1 mRNA的表达与体质量指数（BMI）、腰臀比（WHR）、空腹胰岛素（FINs）、胰岛素抵抗指数（HOMA—IR）、甘油三酯（TG）的表达呈正相关（r=0．963、0．939、0．974、0．924、0．600,均P〈0．01）,与GLUT4 mRNA的表达呈负相关（r=0．866,P〈0．01）,多元逐步回归分析示BMI、HOMA—IR、GLUT4mRNA为FOXO1mRNA的独立相关因素。结论肥胖者的网膜脂肪组织中的FOXO1表达明显增加,FOXO1可能是肥胖和胰岛素抵抗的联系者,可能是通过减少GLUT4的表达引起肥胖者胰岛素抵抗的。     

耐力运动对大鼠葡萄糖运载体基因表达及转位的影响

目的　研究耐力运动对大鼠骨骼肌细胞葡萄糖运载体 4(glucosetransporter 4,GLUT4)基因表达及转位机制的影响。方法　将SD大鼠随机分为两组 :对照组和耐力运动组。耐力运动组大鼠进行 6周游泳训练。用Western印迹法检测大鼠骨骼肌细胞内膜和外膜的GLUT4蛋白含量 ,用Northern杂交法和斑点印迹法检测大鼠骨骼肌细胞内GLUT4mRNA含量。实验前后检测大鼠血清胰岛素和血糖浓度。结果　运动组大鼠经过 6周游泳训练后 ,与对照组大鼠相比 ,骨骼肌细胞内膜GLUT4含量增加 16.0 %(P <0 .0 1) ,细胞外膜GLUT4含量增加 71.9% (P <0 .0 1) ,骨骼肌细胞内GLUT4mRNA含量增加2 5 .6% (P <0 .0 1)。结论　耐力运动可增加骨骼肌细胞内GLUT4基因表达水平 ,促进骨骼肌细胞内的GLUT4从内膜向细胞外膜转位 ,从而提高骨骼肌细胞对葡萄糖的摄取和利用。     

GLUT4 glucose transporter deficiency increases hepatic lipid production and peripheral lipid utilization

A critical defect in type 2 diabetes is impaired insulin-stimulated glucose transport and metabolism in muscle and adipocytes. To understand the metabolic adaptations this elicits, we generated mice with targeted disruption of the GLUT4 glucose transporter in both adipocytes and muscle (AMG4KO). In contrast to total body GLUT4-null mice, AMG4KO mice exhibit normal growth, development, adipose mass, and longevity. They develop fasting hyperglycemia and glucose intolerance and are at risk for greater insulin resistance than mice lacking GLUT4 in only one tissue. Hyperinsulinemic-euglycemic clamp studies showed a 75% decrease in glucose infusion rate and markedly reduced 2-deoxyglucose uptake into skeletal muscle (85-90%) and white adipose tissue (65%). However, AMG4KO mice adapt by preferentially utilizing lipid fuels, as evidenced by a lower respiratory quotient and increased clearance of lipids from serum after oral lipid gavage. While insulin action on hepatic glucose production and gluconeogenic enzymes is impaired, hepatic glucokinase expression, incorporation of 14C-glucose into lipids, and hepatic VLDL-triglyceride release are increased. The lipogenic activity may be mediated by increased hepatic expression of SREBP-1c and acetyl-CoA carboxylase. Thus, inter-tissue communication results in adaptations to impaired glucose transport in muscle and adipocytes that involve increased hepatic glucose uptake and lipid synthesis, while muscle adapts by preferentially utilizing lipid fuels. Genetic determinants limiting this "metabolic flexibility" may contribute to insulin resistance and type 2 diabetes in humans.     

Peripheral but not hepatic insulin resistance in mice with one disrupted allele of the glucose transporter type 4 (GLUT4) gene.

Glucose transporter type 4 (GLUT4) is insulin responsive and is expressed in striated muscle and adipose tissue. To investigate the impact of a partial deficiency in the level of GLUT4 on in vivo insulin action, we examined glucose disposal and hepatic glucose production (HGP) during hyperinsulinemic clamp studies in 4-5-mo-old conscious mice with one disrupted GLUT4 allele [GLUT4 (+/-)], compared with wild-type control mice [WT (+/+)]. GLUT4 (+/-) mice were studied before the onset of hyperglycemia and had normal plasma glucose levels and a 50% increase in the fasting (6 h) plasma insulin concentrations. GLUT4 protein in muscle was approximately 45% less in GLUT4 (+/-) than in WT (+/+). Euglycemic hyperinsulinemic clamp studies were performed in combination with [3-3H]glucose to measure the rate of appearance of glucose and HGP, with [U-14C]-2-deoxyglucose to estimate muscle glucose transport in vivo, and with [U-14C]lactate to assess hepatic glucose fluxes. During the clamp studies, the rates of glucose infusion, glucose disappearance, glycolysis, glycogen synthesis, and muscle glucose uptake were approximately 55% decreased in GLUT4 (+/-), compared with WT (+/+) mice. The decreased rate of in vivo glycogen synthesis was due to decreased stimulation of glucose transport since insulin's activation of muscle glycogen synthase was similar in GLUT4 (+/-) and in WT (+/+) mice. By contrast, the ability of hyperinsulinemia to inhibit HGP was unaffected in GLUT4 (+/-). The normal regulation of hepatic glucose metabolism in GLUT4 (+/-) mice was further supported by the similar intrahepatic distribution of liver glucose fluxes through glucose cycling, gluconeogenesis, and glycogenolysis. We conclude that the disruption of one allele of the GLUT4 gene leads to severe peripheral but not hepatic insulin resistance. Thus, varying levels of GLUT4 protein in striated muscle and adipose tissue can markedly alter whole body glucose disposal. These differences most likely account for the interindividual variations in peripheral insulin action.     

2型糖尿病大鼠骨骼肌葡萄糖转运蛋白-4和磷脂酰肌醇-3-激酶与内脂素的关系

目的研究内脂素对糖尿病大鼠骨骼肌葡萄糖转运蛋白-4（GLUT4）和磷脂酰肌醇-3-激酶（PI3K）表达的影响并探讨其机制。方法健康雄性Wistar大鼠随机分为普通饲料组（N组）、高脂饲料组（H组）、普通饲料糖尿病模型组（N＋S组）及高脂饲料糖尿病模型组（H＋S组）。糖尿病模型组大鼠腹腔注射链脲佐菌素造模。造模成功8周后,两组糖尿病大鼠再分别随机分出一组为V＋N＋S组和V＋H＋S组,腹腔注射内脂素重组蛋白。采用实时定量RT-PCR技术检测骨骼肌GLUT4 mRNA表达, Western blot 技术检测GLUT4和PI3K蛋白表达。结果 N＋S组与N组、H＋S组与H组大鼠骨骼肌GLUT4 mRNA,GLUT4和PI3K蛋白表达水平比较明显减低（P＜0.05）。 V＋N＋S组与N＋S组、V＋H＋S组与H＋S组比较均有所升高（P＜0.05）。结论内脂素可能通过增加PI3K的蛋白表达影响GLUT4的基因表达,导致其蛋白表达增加,从而降低血糖。     

Decreased in vivo glucose uptake but normal expression of GLUT1 and GLUT4 in skeletal muscle of diabetic rats.

This study was designed to determine whether altered glucose transporter expression is essential for the in vivo insulin-resistant glucose uptake characteristic of streptozocin-induced diabetes. Immunofluorescence in rat skeletal muscle colocalizes GLUT4 with dystrophin, both intrinsic to muscle fibers. In contrast, GLUT1 is extrinsic to muscle fibers, probably in perineurial sheath. Immunoblotting shows that levels of GLUT1 and GLUT4 protein per DNA in hindlimb muscle are unaltered from control levels at 7 d of diabetes but decrease to approximately 20% of control at 14 d of diabetes. This decrease is prevented by insulin treatment. In adipose cells of 7 d diabetic rats, GLUT4 levels are depressed. Thus, GLUT4 undergoes tissue-specific regulation in response to diabetes. GLUT4 and GLUT1 mRNA levels in muscle are decreased 62-70% at both 7 and 14 d of diabetes and are restored by insulin treatment. At 7 d of diabetes, when GLUT4 protein levels in muscle are unaltered, in vivo insulin-stimulated glucose uptake measured by euglycemic clamp is 54% of control. This reflects impairment in both glycogen synthesis and glycolysis and the substrate common to these two pathways, glucose-6-phosphate, is decreased approximately 30% in muscle of diabetic rats. These findings suggest a defect early in the pathway of glucose utilization, probably at the step of glucose transport. Because GLUT1 and GLUT4 levels are unaltered at 7 d of diabetes, reduced glucose uptake in muscle probably reflects impaired glucose transporter translocation or intrinsic activity. Later, at 14 d of diabetes, GLUT1 and GLUT4 protein levels are reduced, suggesting that sequential defects may contribute to the insulin-resistant glucose transport characteristic of diabetes.     

Glucose transport and NIDDM.

Three major metabolic abnormalities contribute to hyperglycemia in non-insulin-dependent diabetes mellitus (NIDDM) including defective glucose-induced insulin secretion, elevated rates of hepatic glucose output, and insulin's impaired ability to stimulate glucose uptake in peripheral target tissues (insulin resistance). These functions involve cellular glucose transport in beta-cells, liver, adipose tissue, and skeletal muscle; and, in some instances, abnormalities in glucose transporter isoforms (GLUT) specifically expressed in these tissues may constitute key biochemical lesions underlying defective glucose homeostasis. In animal models of NIDDM, suppression of GLUT2 in beta-cells is correlated with loss of high-Km glucose transport and glucose-sensitive insulin secretion. Although there are no data on humans with NIDDM, GLUT2 loss would constitute an attractive mechanism for defective glucose sensing in beta-cells if it can be shown that transport then becomes rate limiting for glucose metabolism. In the liver, however, hepatocyte glucose transport via GLUT2 probably plays only a permissive role in sustaining increased glucose efflux. Peripheral insulin resistance is associated with decreased glucose transport activity, the likely rate-limiting step for glucose uptake in fat and muscle. Accordingly, the insulin-responsive GLUT4 isoform expressed exclusively in insulin target tissues has been studied intensively in NIDDM. In these studies, pretranslational suppression of GLUT4 appears to be the key mechanism of insulin resistance in adipocytes. However, levels of GLUT4 protein and mRNA are normal in vastus lateralis and rectus abdominis, inferring that defects in GLUT4 functional activity or insulin-mediated translocation cause insulin resistance in muscle. Thus, the intensified study of glucose transport has provided important new insights into NIDDM pathogenesis over the past 5 yr and has presented investigators with additional intriguing hypotheses.