The Effect of Thoracic Operation on Glucose Transporter-4 mRNA Expression by Preoperative Infusion of Glucose

Objective: To investigate the changes in glucose transporter-4(Glut-4) mRNA expression in skeletal muscle before and after the thoracic operation and to observe the changes in Glut-4 mRNA expression by preoperative infusion of glucose. Methods: Twelve cases of elective thoracic operation were randomly divided into two groups, namely ordinary group Ⅰ and glucose infusion group Ⅱ. One gram of intercostal muscle was taken while thorax being opened and closed from patients under general anesthesia. Total RNA of the muscle cells was extracted by TRIzol one-step assay. Reverse transcription-competitive polymerase chain reaction (RT-PCR) was used to determine the Glut-4 mRNA amplification products with β-actin mRNA as an internal control. The Glut-4 mRNA expression was expressed by targeted gene /β-actin ×100%. The plasma glucose and insulin levels were determined at the same time.Results: Glut-4 mRNA expression was significantly reduced(P<0.05) and plasma glucose level increased (P<0.05), while thorax was being closed as compared with those while being opened. However, Glut-4 mRNA expression in glucose infusion group Ⅱ was significantly higher than ordinary group Ⅰ (P<0.01) and plasma glucose level in group Ⅱ was lower than group Ⅰ(P<0.05) when thorax was being closed. Conclusion: The results indicate that the synthesis of Glut-4 is suppressed by the surgical stress of thoracic operation under general anesthesia. We found that preoperative infusion glucose can increase Glut-4 mRNA expression at the same surgical stress and relieve postoperative insulin resistance.

Effect of iron supplementation on glucose transporter 4 expression in adipose tissue and skeletal muscle of pregnant rats

Objective: The main goal of the present study was to investigate the effect of iron supplementation on glucose transporter 4 expressions in adipose tissue and skeletal muscle in female rats during pregnancy. Methods: Twenty-four pregnant Sprague-Dawley rats were randomly divided into 2 groups: a control group with a standard diet (containing iron 150 mg/kg) and an iron-supplementation group with a high-iron diet (containing iron 700 mg/kg) from day 0 to day 21 of pregnancy. Intraperitoneal glucose tolerance test was performed on gestational day 19. On gestational day 21, all of the pregnant rats from each group were sacrificed. The mean neonatal weights were measured and samples of maternal intraabdominal adipose tissue and skeletal muscle were taken to measure the expression of Glucose Transporter 4 (GLUT4) mRNA and protein. Results: Glucose tolerance decreased significantly in the iron supplementation group compared to the control group. The mean neonatal weights in the iron supplementation group were higher than that in the control group. Levels of GLUT4 mRNA in the adipose tissue were reduced by the administrations of high-iron diet. The skeletal muscle GLUT4 mRNA levels were not changed significantly by iron supplementation. Expression of GLUT4 protein both in the adipose tissue and skeletal muscle reduced significantly. Conclusion: These results suggest that iron supplementation during pregnancy would increase neonatal weights and could decrease maternal glucose tolerance by interfering GLUT4 expression in adipose tissue and skeletal muscle of rats.

交泰丸通过激活PI3K/AKT信号通路改善阿尔茨海默病模型小鼠大脑的葡萄糖代谢

目的探讨交泰丸对阿尔茨海默病模型小鼠大脑胰岛素PI3K/AKT通路的影响。方法50只3月龄雄性APP/PS1双转基因小鼠随机分为5组:模型组、交泰丸低剂量组(2.1 g/kg)、交泰丸中剂量组(4.2 g/kg)、交泰丸高剂量组(8.4 g/kg)、多奈哌齐组(3 mg/kg),C57BL/6J雄性小鼠为正常组,10只/组。给药4周后,采用水迷宫和旷场实验评估各组小鼠学习记忆能力,采用HE染色、尼氏染色观察小鼠脑组织神经元病理改变,免疫组化法观察小鼠脑组织Aβ淀粉样斑块沉积情况,ELISA试剂盒测定小鼠空腹血清胰岛素水平,采用Western blot和RT-qPCR检测小鼠脑组织中Aβ42、胰岛素PI3K/AKT通路以及下游GLUTs等相关指标蛋白和mRNA表达水平。结果与正常组小鼠比较,模型组小鼠学习记忆能力受损,小鼠海马神经元细胞数量减少,排列稀疏,小鼠脑组织Aβ淀粉样斑块沉积显著增多(P<0.001),Aβ42蛋白表达水平升高(P<0.05),胰岛素抵抗指数升高(P<0.001),小鼠海马PI3K蛋白以及mRNA表达均降低(P<0.01),海马与皮质AKT蛋白表达(P<0.05)、AKT mRNA表达(P<0.001)、InR蛋白表达(P<0.05),GLUT1、GLUT3、GLUT4蛋白表达(P<0.05)及mRNA表达(P<0.001)均降低,GSK3β蛋白表达(P<0.01)及GSK3βmRNA表达(P<0.001)显著升高。与模型组比较,交泰丸各组和多奈哌齐组小鼠记忆能力明显改善,尤其是交泰丸中剂量组,小鼠海马神经元细胞数量增多,小鼠海马、皮质Aβ淀粉样斑块沉积减少(P<0.01),Aβ42蛋白表达下调(P<0.001),胰岛素抵抗指数降低(P<0.001),小鼠海马、皮质PI3K、AKT、InR、GLUT1、GLUT3、GLUT4蛋白(P<0.05)及mRNA(P<0.01)表达不同程度升高,GSK3β蛋白及mRNA表达降低。结论交泰丸可通过激活APP/PS1双转基因小鼠大脑胰岛素PI3K/AKT通路,调控其下游GLUTs表达水平,提高大脑葡萄糖代谢能力,改善小鼠学习记忆能力,延缓阿尔茨海默病发展进程。

钠-葡萄糖共转运蛋白及其抑制剂对DR的影响研究进展

糖尿病视网膜病变(DR)是一类常见的糖尿病微血管并发症,其发病机制目前尚未完全明确。钠-葡萄糖共转运蛋白(SGLT)是一类调控葡萄糖运输的跨膜蛋白家族,既往研究在视网膜内发现其家族成员SGLT1和SGLT2的表达,提示SGLT对DR发病具有潜在影响。SGLT2介导视网膜周细胞的异常钠依赖性葡萄糖摄取,可能参与了DR早期的微血管病变过程,而SGLT抑制剂可减少高血糖引起的视网膜细胞形态及功能损伤,可能对DR有治疗作用。近期研究发现,编码SGLT2的SLC5A2基因多态性与DR发生风险存在相关性。SGLT2抑制剂目前在临床上用于治疗2型糖尿病,其有助于预防继发的心血管和肾脏相关病变,但关于其在DR疗效方面的研究较少。现有研究结果提示,SGLT2抑制剂对DR具有治疗作用,可能是通过控制DR相关的危险因素、保护视网膜微血管系统、减轻神经相关视网膜病变等机制实现的。本文就SGLT对DR发病的影响、SGLT2抑制剂在预防和治疗DR方面的最新研究进展以及可能的保护机制进行综述。

天花粉对2型糖尿病大鼠糖脂代谢和胰腺组织的影响

目的:探讨中药天花粉对高脂膳食和链脲佐菌素联合诱导的2型糖尿病大鼠的治疗作用及其可能的作用机制。方法:从60只雌雄各半的SD大鼠中随机抽取10只作为正常组,使用普通饲料喂养,剩余的50只大鼠使用高脂饲料喂养。4周后,腹腔注射链脲佐菌素(50 mg/kg),分别于注射后48 h、72 h测定大鼠空腹血糖,将连续2次空腹血糖≥16.7 mmol/L的大鼠确定为实验性糖尿病大鼠模型,根据血糖值将糖尿病大鼠随机分为模型组、二甲双胍组(0.3 mg/kg)、天花粉低剂量组(1.12 g/kg)、天花粉中剂量组(1.68 g/kg)和天花粉高剂量组(2.25 g/kg),每组10只。每天固定时间统一灌胃,持续4周,每周固定时间观察大鼠的一般症状,并测定其摄食量、摄水量、体质量和尿量。给药4周后,所有大鼠提前禁食不禁水12 h,尾静脉采血0.05 mL,测定大鼠空腹血糖,腹主动脉采血后处死大鼠并检测以下指标:各组大鼠的胰腺组织苏木精-伊红切片的病理改变,血清标本中的低密度脂蛋白胆固醇、高密度脂蛋白胆固醇、总胆固醇、三酰甘油、丙氨酸氨基转移酶、天门冬氨酸氨基转移酶等指标的含量。以免疫组化法检测胰腺组织中葡萄糖转运蛋白4的表达。结果:天花粉各给药组大鼠的空腹血糖浓度明显比模型组低(P<0.01或P<0.05);苏木精-伊红染色结果表明,天花粉能够在一定程度上抑制各组2型糖尿病大鼠胰腺组织的病理学改变;天花粉能够显著提升糖尿病大鼠血清中高密度脂蛋白胆固醇的含量,并降低三酰甘油、总胆固醇、低密度脂蛋白胆固醇水平(P<0.05);天花粉给药组大鼠血清丙氨酸氨基转移酶、天门冬氨酸氨基转移酶表达量明显降低(P<0.05);天花粉能上调糖尿病大鼠胰腺组织中葡萄糖转运蛋白4的水平(P<0.05)。结论:天花粉能够改善2型糖尿病大鼠的糖脂代谢,保护胰腺及重要脏器,其作用机制可能与其激活机体的葡萄糖转运蛋白4通路有关。

熊果苷调节PI3K/Akt/GLUT1信号通路对胃癌细胞恶性进展的影响

目的 探讨熊果苷(Arb)调节磷脂酰肌醇-3激酶B/蛋白激酶B/葡萄糖转运蛋白1(PI3K/Akt/GLUT1)信号通路对胃癌细胞恶性进展的影响。方法 使用不同浓度(12.5、25、50、100、200、400 mol/L)Arb处理SNU-601细胞,检测细胞活性,筛选最佳浓度;将细胞分为对照组(Control组)、熊果苷低、中、高浓度组(L-Arb组、M-Arb组、H-Arb组)、熊果苷高浓度+PI3K/Akt激活剂组(H-Arb+740 Y-P组),分别检测细胞凋亡率、细胞周期、葡萄糖摄取、乳酸生成、ATP生成、细胞迁移数和细胞侵袭数;Western blot检测Bax、半胱氨酸天冬氨酸蛋白水解酶3(cleaved-caspase3)、B细胞淋巴瘤-2(Bcl-2)、p-PI3K、PI3K、p-Akt、Akt、GLUT1、HKⅡ蛋白表达。结果 12.5~400 mol/L的Arb可显著抑制SNU-601细胞增殖,选择50、100、200 mol/L的Arb进行后续实验。与Control组比较,L-Arb组、M-Arb组、H-Arb组细胞活性、葡萄糖摄取、乳酸生成、ATP生成、细胞迁移数、细胞侵袭数及Bcl-2、p-PI3K/PI3K、p-Akt/Akt、GLUT1、HKⅡ蛋白表达降低,细胞凋亡率和Bax、cleaved-caspase3蛋白表达增加(P<0.05);与H-Arb组比较,H-Arb+740 Y-P组细胞活性、葡萄糖摄取、乳酸生成、ATP生成、细胞迁移数、细胞侵袭数及Bcl-2、p-PI3K/PI3K、p-Akt/Akt、GLUT1、HKⅡ蛋白表达增加,细胞凋亡率和Bax、cleaved-caspase3蛋白表达降低(P<0.05)。结论 Arb通过抑制PI3K/Akt/GLUT1信号通路抑制胃癌细胞恶性进展。

SGLT2i对糖尿病心肌保护作用及机制研究进展

钠-葡萄糖协同转运蛋白-2抑制剂(SGLT2i)是新型的降糖药物,通过其独特的降糖机制来调整患者的血糖。目前的很多研究发现SGLT2i在降低血糖的同时也能使患者的心功能受益,但是目前其作用机制尚未完全明确,本文对其相关机制的研究进展进行综述。

钠-葡萄糖共转运蛋白2抑制剂在老年2型糖尿病合并常见心血管疾病中的应用进展

老年2型糖尿病(T2DM)患者常有多病共存现象,而合并心血管疾病(CVD)最为常见,是其致残、致死的首要原因。钠-葡萄糖共转运蛋白2抑制剂(SGLT2i)是一种新型降糖药物,其心血管保护作用受到广泛关注,在老年T2DM与CVD共病的治疗上展现出良好的前景。本文就SGLT2i在T2DM合并心力衰竭、高血压、动脉粥样硬化、心肌梗死等常见CVD中的应用研究进展作一综述。

NHE1和GLUTs蛋白水平在缺血性脑损伤再灌注大鼠脑内的表达意义

探讨线栓法构建大脑中动脉缺血(MCAO)大鼠模型脑组织Na^(+)/H^(+)交换蛋白1型(Na^(+)/H^(+)exchanger protein 1,NHE1)和GLUTs蛋白的表达水平。方法为:50只雄性SD大鼠随机分为假手术组(6只)、MCAO模型组(44只),通过线栓法构建大鼠大脑中动脉缺血(Middle cerebral artery occlusion,MCAO)再灌注模型,造模成功后的2 h,4 h,6 h,12 h,24 h各处死6只MCAO大鼠,免疫组化方法观察脑组织形态结构的改变,采用免疫荧光法和western-blot法检测大鼠左侧脑内NHE1,GLUT1及GLUT3表达,并与假手术组比较。与假手术组比较,MCAO模型组大鼠出现明显的神经功能障碍,病理检测结果显示脑组织出现明显的梗死灶,脑组织含水量明显升高,NHE1蛋白和GLUT1蛋白表达水平明显升高(P<0.01),GLUT3蛋白表达明显减少,显著低于假手术组(P<0.01)。结果显示,脑缺氧缺血后脑内NHE1和GLUT3蛋白表达升高,GLUT3蛋白的表达降低可导致脑能量代谢降低,加重缺氧缺血后神经元的损伤。

Intestinal sugar transport

Carbohydrates are an important component of the diet. The carbohydrates that we ingest range from simple monosaccharides （glucose, fructose and galactose） to disaccharides （lactose, sucrose） to complex polysaccharides. Most carbohydrates are digested by salivary and pancreatic amylases, and are further broken down into monosaccharides by enzymes in the brush border membrane （BBM） of enterocytes. For example, lactase-phloridzin hydrolase and sucraseisomaltase are two disaccharidases involved in the hydrolysis of nutritionally important disaccharides. Once monosaccharides are presented to the BBM, mature enterocytes expressing nutrient transporters transport the sugars into the enterocytes. This paper reviews the early studies that contributed to the development of a working model of intestinal sugar transport, and details the recent advances made in understanding the process by which sugars are absorbed in the intestine.

Effect of insulin in combination with selenium on blood glucose and GLUT4 expression in skeletal muscle of streptozotocin-induced diabetic rats

Objective To evaluate the effect of low-dose insulin [1 U/(kg·d)] in combination with selenium [180 g/(kg·d)] on general physiological parameters and glucose transporter (GLUT4) level in skeletal muscle of streptozotocin (STZ)-induced diabetic rats. Methods Diabetic rats were treated with insulin,selenium,and insulin and selenium in combination for four weeks. The level of blood glucose was determined using One Touch SureStep Blood Glucose meter and the level of GLUT4 in skeletal muscle was examined by immunoblotting and immunohistochemistry. Results Our data showed that insulin in combination with selenium could significantly lower blood glucose level and restore the disturbance in GLUT4 level in skeletal muscle. Treatment with insulin was only partially effective in restoring diabetic alterations. Conclusion It can be concluded that there is a synergistic action between insulin and selenium,and that treatment of diabetic rats with combined doses of insulin and selenium is effective in the normalization of blood glucose level and correction of altered GLUT4 distribution in skeletal muscle of diabetic rats.

Kinetics and mechanisms of glucose absorption in the rat small intestine under physiological conditions

Previous studies have shown two components of glucose absorption in the small intestine: a secondary active transport through SGLT1, and unsaturated component, recently attributed mainly to the facilitated diffusion through GLUT2, but the relationship between these two components under physiological conditions remains controversial. In chronic experiments on nonanesthetized rats we investigated for the first time the kinetics of maltose hydrolysis and glucose absorption in the isolated loop of the small intestine in a wide range of maltose and glucose concentrations (25 ÷ 200 mmol/l glucose). The processes were simulated on mathematical models which took into account the current views about mechanisms of hydrolysis and transport of nutrients and geometric characteristics of the intestinal surface. The results of chronic experiments and mathematical simulation have shown that under the close to physiological conditions the glucose transport mediated by SGLT1 is the main mechanism of its absorption in comparison with the unsaturated component. This was demonstrated not only at low, but also at high substrate concentrations. We conclude that correct evaluation of the relative contribution of different mechanisms in glucose transport through the intestinal epithelium requires taking into account the geometric specificities of its surface.

Anti-Hyperglycemic Effect of Single Administered Gardeniae Fructus in Streptozotocin-Induced Diabetic Mice by Improving Insulin Resistance and Enhancing Glucose Uptake in Skeletal Muscle

The mechanisms of Gardeniae Fructus (GF) for anti-hyperglycemic action were demonstrated in streptozotocin (STZ)-diabetic mice. Six hours after single intraperitoneal administration of GF (300 mg/kg) or H2O into 3 hour-fasted STZ-diabetic mice, glucose and insulin tolerances were assessed by intraperitoneal glucose (1.5 g/kg) tolerance test (IPGTT) and intraperitoneal insulin (0.65 U/kg) tolerance test (IPITT), respectively. Effects of GF on insulin signaling pathways in soleus muscle such as glucose uptake, expression of glucose transporter 4 (GLUT4) in the plasma membrane and phosphorylation of Akt (P-Akt) in cytosolic fraction were examined in STZ-diabetic mice. In IPGTT test, GF significantly accelerated clearance of exogenous glucose and its glucose-lowering action was greater than H2O-treated controlin STZ-diabetic mice. GF also promoted an exogenous glucose-increased insulin level in STZ-diabetic mice. In IPITT test, GF decreased glucose level to the greater extent than H2O-treated control in STZ-diabetic mice. Furthermore, GF significantly decreased high HOMA-IR in STZ-diabetic mice from 21.6 ± 2.4 to 12.4 ± 1.9 (mg/dl × μU/ml). These results implied that GF improved insulin resistance in STZ-diabetic mice. GF increased glucose uptake of soleus muscle 1.5 times greater than H2O-treated control in STZ-diabetic mice. GF enlarged insulin (10 nmol/ml)-increased glucose uptake to 1.8 time-greater. Correspondingly, GF increased expression of GLUT4 in the plasma membrane of soleus muscle to 1.4 time-greater, and P-Akt in the cytosolic fraction of soleus muscle to 1.9 time-greater than those in H2O-treated control. In conclusion, the improvement of GF on insulin resistance is associated with the repair of insulin signaling via P-Akt, GLUT4 and glucose uptake pathway in soleus muscle of STZ-diabetic mice.

Kruppel样因子15通过调控核苷酸结合寡聚化结构域样受体蛋白3表达影响胰岛素抵抗实验研究

目的:探讨Kruppel样因子15(KLF15)是否通过调控核苷酸结合寡聚化结构域样受体蛋白3(NLRP3)表达影响胰岛素抵抗。方法:建立小鼠模型和细胞模型,细胞蛋白电泳检测细胞内目的蛋白表达,聚合酶链反应(PCR)检测KLF15表达量,Western blot检测NLRP3相对表达量,免疫组化法检测组织KLF15表达,免疫荧光染色检测细胞增殖相关蛋白。结果:在链脲佐菌素(STZ)诱导小鼠模型中,小鼠诱导后1~4个月,血清KLF15 mRNA表达量水平被抑制。用10、20、40 mmol/L葡萄糖诱导HepG2细胞24 h后,细胞内KLF15 mRNA表达量水平随葡萄糖浓度升高而减少(均P<0.05)。小鼠组织中,KLF15、葡萄糖转运蛋白4(GLUT4)、胰岛素受体底物1(IRS1)在空白组表达最高,其次分别为1、2、4个月组;NLRP3在空白组表达最低,1、2、4个月组依次升高(均P<0.05)。在体外模型中,si-NLRP3质粒可以降低NLRP3表达量;抑制NLRP3表达可以减少干扰素-γ(INF-γ)、肿瘤坏死因子-α(TNF-α)、白细胞介素-6(IL-6)和IL-1β表达,同时增加IRS1、GLUT4表达量;NLRP3过表达质粒可以促进NLRP3表达量,过表达NLRP3可以促进INF-γ、TNF-α、IL-6和IL-1β表达,同时减少IRS1、GLUT4表达量;上调KLF15可以抑制NLRP3蛋白表达,抑制KLF15可以促进NLRP3蛋白表达(均P<0.05)。结论:KLF15表达量与2型糖尿病(T2DM)胰岛素抵抗有关,KLF15低表达量可能会增加胰岛素抵抗。KLF15可能通过抑制NLRP3表达量减少T2DM胰岛素的炎症水平,抑制胰岛素抵抗。KLF15可能为胰岛素抵抗的T2DM的潜在治疗和诊断靶点,为以后的相关研究提供实验依据。

葡萄糖转运蛋白1在肿瘤细胞代谢重编程中的作用

近年来,随着对肿瘤生物学研究的不断深入,人们对复杂的肿瘤代谢重编程更新、更全面的认识。葡萄糖转运蛋白1(glucose transport protein-1,GLUT-1)在不同肿瘤细胞的质膜上有不同程度的过度表达,过表达的GLUT-1会使肿瘤细胞摄入更多的葡萄糖以重编程细胞的代谢模式,。同时,对肿瘤微环境的改变有着重要的影响。并且,在肿瘤中GLUT-1的调节是近年来关注的重点,目前,已报道的上游调控因子主要有PTEN基因编码的蛋白质(phosphatase and tension homolog deleted on chromosome ten,PTEN)、缺氧诱导因子(hypoxia inducible factor,HIF),GLUT-1还会通过影响p53和细胞致瘤基因(cellular-myelocytomatosis viral oncogene,c-Myc)通路等在肿瘤的发生与发展中发挥着重要的作用。本文主要综述GLUT-1的结构与功能、在肿瘤代谢重编程中通过转运不同底物对肿瘤的影响、GLUT-1的调节和目前针对GLUT-1的治疗等。同时,阐述了GLUT-1与肿瘤代谢重编程的研究现状,分析了当前存在的问题,旨在为抗肿瘤机制研究以及恶性肿瘤靶向治疗研究提供参考。

SGLT2抑制剂与GLP-1受体激动剂对2型糖尿病患者心血管影响的研究

2型糖尿病(T2DM)患者容易并发微血管和大血管病变,是心血管疾病发生的独立危险因素。钠-葡萄糖协同转运蛋白2(SGLT2)抑制剂与胰高血糖素(GLP)-1受体激动剂都已明确对T2DM患者心血管有益处,但是又有不同的优缺点,本文就这两种药物对T2DM患者心血管的影响作一综述。

Glucose supplementation improves intestinal amino acid transport and muscle amino acid pool in pigs during chronic cold exposure

Mammals in northern regions chronically suffer from low temperatures during autumn-winter seasons.The aim of this study was to investigate the response of intestinal amino acid transport and the amino acid pool in muscle to chronic cold exposure via Min pig models(cold adaptation)and Yorkshire pig models(non-cold adaptation).Furthermore,this study explored the beneficial effects of glucose supplementation on small intestinal amino acid transport and amino acid pool in muscle of cold-exposed Yorkshire pigs.Min pigs(Exp.1)and Yorkshire pigs(Exp.2)were divided into a control group(17℃,n=6)and chronic cold exposure group(7℃,n=6),respectively.Twelve Yorkshire pigs(Exp.3)were divided into a cold control group and cold glucose supplementation group(8℃).The results showed that chronic cold exposure inhibited peptide transporter protein 1(PepT1)and excitatory amino acid transporter 3(EAAT3)expression in ileal mucosa and cationic amino acid transporter-1(CAT-1)in the jejunal mucosa of Yorkshire pigs(P<0.05).In contrast,CAT-1,PepT1 and EAAT3 expression was enhanced in the duodenal mucosa of Min pigs(P<0.05).Branched amino acids(BCAA)in the muscle of Yorkshire pigs were consumed by chronic cold exposure,accompanied by increased muscle RING-finger protein-1(MuRF1)and muscle atrophy F-box(atrogin-1)expression(P<0.05).More importantly,reduced concentrations of dystrophin were detected in the muscle of Yorkshire pigs(P<0.05).However,glycine concentration in the muscle of Min pigs was raised(P<0.05).In the absence of interaction between chronic cold exposure and glucose supplementation,glucose supplementation improved CAT-1 expression in the jejunal mucosa and PepT1 expression in the ileal mucosa of cold-exposed Yorkshire pigs(P<0.05).It also improved BCAA and inhibited MuRF1 and atrogin-1 expression in muscle(P<0.05).Moreover,dystrophin concentration was improved by glucose supplementation(P<0.05).In summary,chronic cold exposure inhibits amino acid absorption in the small intestine,depletes BCAA and promotes protein degradation in muscle.Glucose supplementation ameliorates the negative effects of chronic cold exposure on amino acid transport and the amino acid pool in muscle.

高强度间歇运动改善骨骼肌损伤和提高大鼠运动能力的机制

背景:高强度间歇运动增强机体适应性,提高运动表现,其潜在机制可能与骨骼肌内腺苷酸活化蛋白激酶(AMP-activated protein kinase,AMPK)的磷酸化水平有关。目的:明确高强度间歇运动减轻力竭运动诱导的骨骼肌损伤与提高运动能力的作用,并阐明此过程中AMPK介导葡萄糖转运蛋白4的变化与作用机制。方法:取45只雄性SD大鼠,采用随机数字表法分为对照组、力竭运动组、高强度间歇+力竭运动组,每组15只。对照组大鼠不进行任何干预;力竭运动组大鼠以25-28 m/min的速度在跑台上运动至力竭;高强度间歇+力竭运动组进行3 d的高强度间歇运动训练(每天以28 m/min的速度在跑台上运动4次,每次10 min,穿插10 min休息),高强度间歇运动结束后24 h复制力竭运动模型;记录大鼠运动距离。力竭运动后,检测各组大鼠血浆肌酸激酶、超氧化物歧化酶水平,TUNEL染色与Western Blot检测腓肠肌细胞凋亡情况,Western Blot检测腓肠肌组织内AMPK磷酸化水平,免疫荧光染色与Western Blot检测腓肠肌组织内葡萄糖转运蛋白4表达与易位情况。结果与结论:①高强度间歇+力竭运动组大鼠的运动距离大于力竭运动组(P<0.05);与对照组比较,力竭运动组肌酸激酶、超氧化物歧化酶水平升高(P<0.05);与力竭运动组比较,高强度间歇+力竭运动组肌酸激酶、超氧化物歧化酶水平降低(P<0.05);②TUNEL染色与Western Blot检测显示,力竭运动组腓肠肌细胞凋亡率大于对照组(P<0.05),高强度间歇+力竭运动组腓肠肌细胞凋亡率小于竭运动组(P<0.05),3组间凋亡相关蛋白Bax和Bcl-2表达无差异(P>0.05);③Western Blot检测显示,与对照组比较,力竭运动组AMPK和p-AMPK蛋白表达升高(P<0.05);与力竭运动组比较,高强度间歇+力竭运动组AMPK蛋白表达降低(P<0.05),p-AMPK蛋白表达升高(P<0.05);④免疫荧光染色与Western Blot检测显示,与对照组相比,力竭运动组骨骼肌纤维的细胞膜葡萄糖转运蛋白4表达增多,高强度间歇+力竭运动组骨骼肌纤维的质膜葡萄糖转运蛋白4表达增多;⑤结果显示,高强度间歇运动减轻力竭运动引起的肌纤维损伤,通过提高运动中AMPK磷酸化的水平与效率,促进骨骼肌中葡萄糖转运蛋白4的表达与易位,提高大鼠运动能力。

Nuciferine relieves type 2 diabetes mellitus via enhancing GLUT4 expression and translocation

Nuciferine contained in lotus leaves have been confirmed to have the effect of ameliorating hyperlipemia and hyperglycemia.A laser scanning confocal microscope was used to track the translocation of glucose transporter 4(GLUT4)in L6 cells and the changes in intracellular Ca^(2+)levels in real time,and related protease inhibitors combined with western blotting were used to explore the mechanism of nuciferine.Meanwhile,KK-Ay mice,the spontaneous type 2 diabetic mice,were used to evaluate the in vivo activity of nuciferine.In this study,the in vitro studies indicated that nuciferine-induced GLUT4 translocation was regulated by G protein-PLC-PKC and AMPK pathways and nuciferine-enhanced intracellular Ca^(2+)was mediated by G protein-PLC-IP3-IP3R pathway,the increase in intracellular Ca^(2+)caused by nuciferine was not directly related to GLUT4 translocation,but both promote glucose uptake.The in vivo results suggested that nuciferine ameliorated weight gain induced by high-fat diet,abnormal lipid metabolism and the symptoms of insulin resistance in KK-Ay diabetic mice.Western blot results suggested that nuciferine increased AMPK and PKC phosphorylation levels in skeletal muscle and liver,and enhanced GLUT4 expression in skeletal muscle.Taken together,this research showed that nuciferine has the non-negligible potential in the treatment of type 2 diabetes mellitus.

糖耐康改善KKAy小鼠Toll样受体4通路及葡萄糖转运子4的作用机制研究

目的:观察中药糖耐康对KKAy小鼠血糖、体质量及Toll样受体4(TLR4)通路中白细胞介素6(IL-6)、核因子κB激酶β抑制物(IKKβ)及葡萄糖转运蛋白4(GluT4)影响,分析其改善2型糖尿病的可能作用机制。方法:选取无特定病原体(SPF)级自发性2型糖尿病动物KKAy小鼠及C57BL/6J小鼠,给予高脂饲料喂养,连续8周给药,评价血糖及体质量。并采用半定量酶联免疫吸附测定(ELISA)检测血浆中IL-6及GluT4的水平。蛋白质印迹法检测肝组织TLR4蛋白表达、肌肉组织IKKβ蛋白表达水平。结果:中药糖耐康高剂量组,能够显著降低血糖水平(P<0.05),具有一定抑制体质量增长的趋势。同时能够下调IL-6水平,上调GluT4的水平(P<0.01,P<0.05),抑制TLR4及IKKβ蛋白表达(P<0.01,P<0.05)。结论:糖耐康可能通过下调脂多糖(LPS)介导的TLR4通路中关键炎症介质的水平,减轻低度炎症反应,在一定程度上抑制炎症级联效应,同时提高胰岛素信号转导受体后途径中GluT4的转位及活性水平,共同达到改善胰岛素抵抗状态的作用。