胰岛素对高糖状态下血管内皮细胞凋亡、eNOS、bcl-xL、bax表达的影响

高浓度葡萄糖使人脐静脉内皮细胞（HUVEC）凋亡增加，bel—xL和内皮型一氧化氮合酶（eNOS）表达减少；加入生理浓度或高浓度Ins后，HUVEC凋亡显著减少，bcl-xL、bax和eNOS表达增加；HUVEC凋亡与eNOS、bcl-xL、bax表达均呈负相关（r=0．85，r=-0．81）。表明胰岛素可以抑制高糖引起的HUVEC凋亡，该作用可能与bcl-xL、bax和eNOS表达增加有关。     

胰岛素介导的内皮依赖性血管舒张功能与高血糖关系的实验研究

目的：研究不同浓度胰岛素，葡萄糖对培养血管内皮细胞一氧化氮（NO）产生的影响，探讨糖尿病时内皮依赖性血管舒张异常的作用机制。方法：用放免法测定内皮细胞cGMP水平来反映NO的量，半定量RT－PCR检测NO合酶（eNOS)mRNA水平。结果：胰岛素（0.18-6.0nmol/L)，葡萄糖（20mmol/L,40mmol/L)能增加内皮细胞cGMP产量，并呈浓度和时间依赖性；高浓度葡萄糖上调eNOS mRNA水平，而胰岛素对其无影响，在高浓度葡萄糖下，胰岛素（6.0nmol/L)刺激NO的生成作用明显降低。结论：胰岛素介导的内皮依赖性血管扩张与胰岛素刺激内皮细胞NO合成有关；血管内皮对胰岛素的敏感性减低是胰岛素抵抗的一部分；高浓度葡萄糖可能会抑制胰岛素介导的内皮依赖性血管舒张。     

罗格列酮对高胰岛素培养的内皮细胞一氧化氮的影响及其机制研究

目的观察罗格列酮（RGZ）对高胰岛素培养的人脐静脉内皮细胞（HUVEC）NO浓度和内皮型一氧化氮合酶（eNOS）、磷酯酰肌醇3激酶（P13K）和蛋白激酶B（PKB）表达的影响,探讨RGZ改善高胰岛素状态下内皮功能障碍的信号转导机制。方法高浓度胰岛素培养HUVEC72h,并用不同浓度的RGZ进行干预。检测NO浓度,PI3K mRNA的表达,PKB、eNOS总蛋白和PKB丝氨酸473（PKB-Ser473）、eNOS丝氨酸1177（eNOS-Ser1177）的磷酸化表达。结果高浓度胰岛素培养HUVEC能呈剂帚和时间依赖性地降低N0的浓度,抑制内皮细胞P13KmRNA表达和PKB-Ser473、eNOS-Ser1177的磷酸化。用RGZ干预能硅著升高高胰岛素培养的内皮细胞NO的浓度和PKB、eNOS的磷酸化,增强PI3KmRNA表达;eNOS和P13K阻断剂均能阻断RGZ对高胰岛素培养的内皮细胞中NO浓度的升高,PI3K阻断剂还能阻断RGZ对高胰岛素培养内皮细胞PKB、eNOS的磷酸化。结论高胰岛素能下调P13K／PKB／eNOs信号通路而抑制内皮细胞NO的产生,RGZ能通过上调PI3K／PKB通路而增强高胰岛素培养的内皮细胞eNOS的活性和NO的产生。     

罗格列酮对2型糖尿病大鼠主动脉内皮依赖性血管舒张功能的影响

目的观察2型糖尿病（T2DM）大鼠胸主动脉内皮依赖性血管舒张功能和一氧化氮（NO）、一氧化氮合酶（eNOS）的变化及罗格列酮（RSG）治疗对其内皮功能的影响。方法SD大鼠经高糖高脂喂养6周后予小剂量链脲佐菌素腹腔注射建立T2DM大鼠模型，糖尿病大鼠又分为对照（DM）组和RSG治疗组，RSG组用RSG干预8周，另选正常大鼠为正常对照（NC）组。实验终止时用正常葡萄糖高胰岛素钳夹技术的葡萄糖输注率（GIR）评价胰岛素抵抗，观察大鼠离体主动脉内皮依赖性血管舒张反应和主动脉NO、eNOS的变化。结果T2DM大鼠GIR、胸主动脉内皮依赖性血管舒张反应、主动脉NO含量及eNOS阳性表达较NC组显著降低（P〈0、01），RSG治疗后上述指标均显著升高（P〈0．05）。结论T2DM大鼠存在内皮依赖性血管舒张功能紊乱，RSG治疗可改善内皮功能，增强NO水平和eNOS的活性。     

高糖对大鼠脂肪细胞胰岛素信号蛋白磷酸化的影响

目的 探讨高浓度葡萄糖（高糖）对原代培养大鼠脂肪细胞的葡萄糖转运活动、胰岛素信号蛋白磷酸化及表达的影响。方法 分离的大鼠脂肪细胞在5，10，15和25mmol/L葡萄糖中孵育24h，然后测定：糖转运活动；胰岛素受体（IR）、胰岛素受体底物（IRS）1、2及蛋白激酶B（PKB）的磷酸化；IRS1，IRS2，肌醇磷脂－3－激酶85亚单位（p85)和PKB的蛋白表达。结果 高糖抑制了这些细胞的葡萄糖转运活动，削弱了IR、IRS1的酪氨酸磷酸化及PKB的丝氨酸磷酸化；下调IRS1而上调IRS2蛋白表达。结论 高糖能抑制脂肪细胞的糖转运活动，诱导胰岛素抵抗。其作用机制与影响胰岛素信号蛋白多部位的磷酸化及蛋白表达有关。     

C肽对人脐静脉内皮细胞凋亡的影响及其与内皮型一氧化氮合酶表达的相关性分析

目的探讨C肽对高糖状态下人脐静脉内皮细胞(HUVEC)凋亡的影响,并对凋亡与内皮型一氧化氮合酶(eNOS)表达进行相关性分析。方法内皮细胞凋亡定性用磷脂酰丝氨酸外翻分析(AnnexinV法),凋亡定量采用细胞DNA片段酶联免疫吸附测定法(ELISA)。检测内皮细胞eNOS表达采用半定量逆转录聚合酶链反应(SQRTPCR)法。结果高浓度葡萄糖(33.3mmol/L)使HUVEC凋亡增加(P<0.01),eNOS表达减少,加入生理浓度(1.0nmol/L)或高浓度(50.0nmol/L)C肽后,凋亡显著减少(P<0.05),eNOS表达增加,HUVEC凋亡与eNOS表达相关(r=-0.845,P<0.01)。结论高糖可导致HUVEC凋亡增加;高浓度或生理浓度的C肽可抑制高糖引起的HUVEC凋亡;HUVEC凋亡与eNOS表达呈负相关。     

高浓度葡萄糖对乳鼠心肌细胞肿瘤坏死因子-α基因表达的影响

目的：观察高糖对不同状态下乳鼠心肌细胞肿瘤坏死因子-α（TNF—α）基因表达的影响,探讨TNF—α在糖尿病心肌病的非特异性炎症中的作用机制。方法：体外培养乳鼠心肌细胞,分别用不同浓度的葡萄糖（0、20、30、50mmol／L）干预正常心肌细胞、胰岛素抵抗心肌细胞,采用逆转录聚合酶链反应检测细胞TNF-α mRNA的表达水平,并在透射电镜下观察心肌细胞结构的变化。结果：（1）在50mmol／L葡萄糖作用下,正常心肌细胞TNF—α mRNA表达（0．58±0．03）明显高于20mmol／L（0．27±0．02）、30mmol／L（0．29±0．05）葡萄糖作用的正常心肌细胞,而后两组之间比较无统计学差异。（2）胰岛素抵抗心肌细胞在0、20、30、50mmol／L葡萄糖作用下,各组心肌细胞TNF-α mRNA表达均有显著性差异（P〈0．05）,并随着葡萄糖浓度的提高,TNF—α mRNA表达越高;在相同浓度葡萄糖作用下,胰岛素抵抗心肌细胞TNF—α mRNA表达明显高于正常心肌细胞。（3）在高浓度葡萄糖作用下,正常心肌细胞和胰岛素抵抗心肌细胞出现线粒体肿胀,髓样结构形成,胞内脂滴增多等细胞结构损伤性改变。结论：高糖作用下胰岛素抵抗心肌细胞TNF—α mRNA表达明显增加,引起胞内脂滴增多等细胞结构变化。     

高糖和高胰岛素对影响血管平滑肌细胞舒缩信号分子的作用

目的观察高糖和高胰岛素对几个调控血管平滑肌细胞(VSMC)舒缩功能信号分子的作用,探讨糖尿病并发高血压的分子机制。方法将培养的大鼠主动脉VSMC随机分成对照组、高糖组(葡萄糖浓度25 mmol/L)、高胰岛素组(胰岛素浓度50μU/ml)、高糖+高胰岛素组、生理浓度胰岛素组(胰岛素浓度10μU/ml)、高糖+生理浓度胰岛素组。蛋白免疫印迹法测定细胞诱导型一氧化氮合酶(iNOS)、内皮型一氧化氮合酶(eNOS)、小分子鸟苷酸蛋白A(RhoA)、Rho激酶-1(ROCK-1)蛋白表达,比率荧光倒置显微镜检测细胞内钙水平([Ca2+]i)。结果高糖组iNOS、eNOS表达减少,[Ca2+]i升高,RhoA、ROCK-1表达明显升高;高胰岛素组iNOSe、NOS表达明显升高,[Ca2+]i明显降低,RhoA、ROCK-1无明显改变;生理胰岛素组iNOSe、NOS表达明显升高,[Ca2+]i、RhoA、ROCK-1无明显改变;当同时给予胰岛素和葡萄糖刺激时,胰岛素可拮抗高糖对上述4种分子的蛋白表达及[Ca2+]i的增加。结论高糖损害VSMC正常收缩舒张功能,而胰岛素可拮抗高糖对VSMC收缩舒张功能的损害作用。     

葡萄糖对人血管内皮细胞多元醇通路的激活作用及其机理

观察葡萄糖对人血管内皮细胞多元醇通路的影响 ,并探讨其作用机理。体外培养人脐静脉内皮细胞 ,加不同浓度葡萄糖或作用不同时间 ,采用高效液相色谱仪、硝酸还原酶法、生物化学检测及逆转录聚合酶链反应等方法测定内皮细胞山梨醇、一氧化氮、醛糖还原酶活性及醛糖还原酶基因mRNA。结果发现 ,经高浓度葡萄糖处理的人脐静脉内皮细胞山梨醇浓度明显高于对照组 (P <0 .0 5) ,一氧化氮浓度明显低于对照组 (P <0 .0 5)。醛糖还原酶基因mRNA水平及其活性均呈浓度及时间依赖性 ,但是内皮细胞经 2 2mmol L葡萄糖作用 48h或 44mmol L葡萄糖作用 2 4h后 ,醛糖还原酶基因mRNA水平及其活性均不再升高 ,而呈下降趋势 (P <0 .0 5)。结果提示 ,高浓度葡萄糖能引起内皮细胞功能改变 ,其机制可能是高浓度葡萄糖能增强醛糖还原酶基因的转录并提高其活性 ,从而活化多元醇通路。     

不同浓度葡萄糖对猪胎胰β细胞发育的影响

采用不同浓度葡萄糖加入猪胎胰培养，观察其对猪胎胰β细胞发育的影响，结果显示：妊娠１０￣１２周之猪胎胰β细胞，在不同浓度的葡萄糖环境中（２．８￣１１．２ｍｍｏｌ／Ｌ），培养两周即可达到功能成熟，并以低糖环境（２．８ｍｍｏｌ／Ｌ）为最佳，其急、慢性胰岛素的分泌均优于高糖（１１．２ｍｍｏｌ／Ｌ）及无糖环境。     

The relationship between insulin resistance and polymorphisms of the endothelial nitric oxide synthase gene in patients with coronary artery disease

Nitric oxide (NO) regulates endothelial function and is believed to prevent atherogenesis. In endothelial cells, endothelial nitric oxide synthase (eNOS) is expressed constitutively, and regulates NO synthesis. A mutation of the eNOS gene has been associated with the development of coronary artery disease (CAD). The development of CAD is also influenced by insulin resistance, and recent studies suggest that NO might affect cellular insulin activity. We investigated the association between eNOS polymorphisms and insulin resistance in patients with CAD. We screened 45 patients with a history of myocardial infarction (MI), angina pectoris (AP), or coronary spasm. Genotypes were determined by polymerase chain reaction-restriction fragment-length polymorphism analysis. We examined two polymorphisms of the eNOS gene (The T(-786)-->C variant and the missense Glu298Asp variant). Insulin resistance was measured by determining the plasma immunoreactive insulin concentration at the 120 min time point (IRI 120) of a 75 g oral glucose tolerance test. The IRI 120 of the T(-786)-->C variant group was higher than that for the control group (p<0.05). This finding demonstrates that the T(-786)-->C mutation in the eNOS gene decreases insulin sensitivity.     

Association of (-)786T-C mutation of endothelial nitric oxide synthase gene with insulin resistance

AIMS/HYPOTHESIS: Endothelial derived nitric oxide synthase ( eNOS) gene polymorphisms affect eNOS activity and are associated with abnormal vasomotility and impaired local blood flow. A decrease in local blood flow has been reported to cause insulin resistance. The aim of this study was to examine a possible association of two eNOS polymorphisms, Glu298Asp (G894T) in exon 7 and (-)786T-C mutation with insulin resistance. METHODS: Genotypes of both Glu298Asp and (-)786T-C mutation were examined by the PCR-RFLP method. Plasma nitrate and nitrite concentrations were also measured. RESULTS: The allele frequencies of both polymorphisms showed no considerable differences in 233 non-diabetic subjects and 301 patients with Type II (non-insulin-dependent) diabetes mellitus. Non-diabetic subjects with the (-)786C allele had (p<0.05) higher fasting plasma insulin and homeostasis model assessment of insulin resistance than those with the (-)786T/ (-)786T genotype. Diabetic subjects with (-)786C allele showed higher HbA(1c) than those with the (-)786T/(-)786T genotype. A euglycaemic hyperinsulinemic clamp study done on 71 of the 301 patients showed a lower glucose infusion rate in diabetic patients with the (-)786C allele than those without it. In diabetic patients with the (-)786C allele, plasma nitrate and nitrite concentrations were lower than in subjects without it (p=0.026). No differences were observed between mutant carriers of Glu298Asp and non-carriers among both non-diabetic subjects and Type II diabetic patients. CONCLUSIONS/INTERPRETATION: The (-)786T-C mutation of the eNOS gene is associated with insulin resistance in both Japanese non-diabetic subjects and Type II diabetic patients.     

高糖诱导的大鼠肾小球系膜细胞中eNOS/NO的变化及调节机制研究

目的:探讨高糖条件下大鼠肾小球系膜细胞(GMCs)中内皮一氧化氮合酶一氧化氮(eNOS/NO)的变化及可能的调节机制.方法:将大鼠GMCs常规培养在含5.5 mmol/L葡萄糖的RPMIl640培养液中,用胰蛋白酶-乙二胺四乙酸(EDTA)混合消化酶传代.用RT、实时-PCR和Western blot测定GMCs中eN...     

The role of endothelial insulin signaling in the regulation of glucose metabolism

The skeletal muscle is one of the major target organs of insulin and plays an essential role in insulin-induced glucose uptake. Some evidence indicates that insulin delivery to skeletal muscle interstitium through the endothelial cells is the rate-limiting step in insulin-stimulated glucose uptake. Researchers have also found that this process is impaired by insulin resistance in type 2 diabetes and obesity. A recent study of ours demonstrated that insulin signaling in the endothelial cells plays a pivotal role in the regulation of glucose uptake by the skeletal muscle. Specifically, impaired insulin signaling in the endothelial cells, with reduction of insulin-induced eNOS phosphorylation, causes attenuation of the insulin-induced capillary recruitment and insulin delivery, which, in turn reduces glucose uptake by the skeletal muscle in high-fat diet-fed mice. Moreover, restoration of the insulin-induced eNOS phosphorylation in the endothelial cells completely reverses the reduction in the capillary recruitment and insulin delivery, and as a result, significantly restores glucose uptake by the skeletal muscle. In the present review, we describe the recent progress in research on the physiological and pathophysiological roles of endothelial insulin signaling in the regulation of insulin-induced glucose uptake by the skeletal muscle.     

Effects of resveratrol on NO secretion stimulated by insulin and its dependence on SIRT1 in high glucose cultured endothelial cells

To investigate the effects of resveratrol on the secretion of NO induced by insulin in high glucose cultured primary human umbilical vein endothelial cells (HUVEC). HUVEC were treated with 1 μmol/l resveratrol for 24 h before cultured in high glucose medium for 48 h, then all cells were stimulated by 100 nmol/l insulin for 30 min. Method based on nitric acid reductase was used to analyze the NO contents in the supernatant. Cells were collected to analyze the expression of eNOS, endothelin-1, E-selectin, and SIRT1. In order to investigate the dependence of resveratrol on SIRT1, the effects of resveratrol on cells treated by SIRT1 siRNA were also examined. Compared with control cells, high glucose decreased the secretion of NO induced by insulin. Resveratrol treatment increased the expression of SIRT1 and the secretion of NO. After interfering the expression of SIRT1 using SIRT1 siRNA, the effects of resveratrol on the NO secretion induced by insulin was impaired. Resveratrol also counteracted other pro-atherosclerotic effects of high glucose, including the up-regulating roles of high glucose on the expression of endothelin-1 mRNA and E-selectin mRNA, and the down-regulating roles of high glucose on the expression of eNOS mRNA and the basal NO secretion without the stimulating of insulin. Resveratrol can improve the NO stimulating function of insulin in high glucose cultured HUVEC in SIRT1-dependent manner. Thus, our results imply that resveratrol may have the preventive roles of atherosclerosis in diabetic patients.     

Activation of IKKbeta by glucose is necessary and sufficient to impair insulin signaling and nitric oxide production in endothelial cells

Hyperglycemic impairment of nitric oxide (NO) production by endothelial cells is implicated in the effect of diabetes to increase cardiovascular disease risk, but the molecular basis for this effect is unknown. In skeletal muscle, diabetes induces activation of inhibitor kappaB kinase (IKKbeta), a key cellular mediator of the response to inflammatory stimuli, and this impairs insulin signal transduction via the insulin receptor substrate-phosphatidylinositol 3-OH kinase (IRS-1/PI3-kinase) pathway. Since activation of endothelial nitric oxide synthase (eNOS) is dependent on IRS-1/PI3-kinase signaling, we hypothesized that activation of IKKbeta may contribute to the effect of glucose to impair NO production. Here, we show that exposure of bovine aortic endothelial cells to high glucose (25 mM) for 24 h impaired insulin-mediated tyrosine phosphorylation of IRS-1, serine phosphorylation of Akt, activation of eNOS, and production of NO. High glucose treatment also activated IKKbeta, and pretreatment with aspirin, a pharmacological inhibitor of IKKbeta, prevented both glucose-induced IKKbeta activation and the effect of high glucose to impair insulin-mediated NO production. These adverse responses to glucose were also blocked by selective inhibition of IKKbeta signaling via overexpression of a kinase-inactive form of the enzyme. Conversely, overexpression of wild-type IKKbeta recapitulated the deleterious effect of high glucose on insulin-mediated activation of eNOS. These data demonstrate that activation of IKKbeta plays a critical and novel role to mediate the deleterious effects of high glucose on endothelial cell function.     

Globular adiponectin improves high glucose-suppressed endothelial progenitor cell function through endothelial nitric oxide synthase dependent mechanisms

Plasma levels of adiponectin, an adipose-specific protein with putative anti-atherogenic properties, could be down-regulated in obese and diabetic subjects. Recent insights suggest that the injured endothelial monolayer is regenerated by circulating endothelial progenitor cells (EPCs), but high glucose reduces number and functions of EPCs. Here, we tested the hypothesis that globular adiponectin can improve high glucose-suppressed EPC functions by restoration of endothelial nitric oxide synthase (eNOS) activity. Late EPCs isolated from healthy subjects appeared with cobblestone shape at 2-4 weeks. EPCs were incubated with high glucose (25 mM) and treatment with globular adiponectin for functional study. Migration and tube formation assays were used to evaluate the vasculogenetic capacity of EPCs. The activities of eNOS, Akt and concentrations of nitric oxide (NO) were also determined. Administration of globular adiponectin at physiological concentrations promoted EPC migration and tube formation, and dose-dependently upregulated phosphorylation of eNOS, Akt and augmented NO production. Chronic incubation of EPCs in high-glucose medium significantly impaired EPC function and induced cellular senescence, but these suppression effects were reversed by treatment with globular adiponectin. Globular adiponectin reversed high glucose-impaired EPC functions through NO- and p38 MAPK-related mechanisms. In addition, nude mice that received EPCs treated with adiponectin in high glucose medium showed a significant improvement in blood flow than those received normal saline and EPCs incubated in high glucose conditions. The administration of globular adiponectin improved high glucose-impaired EPC functions in vasculogenesis by restoration of eNOS activity. These beneficial effects may provide some novel rational to the vascular protective properties of adiponectin.