脂联素球状结构域对胰岛素抵抗模型脂肪细胞及胰岛素信号转导的影响

将3T3-L1前脂肪细胞诱导分化为成熟的脂肪细胞,用软脂酸制备脂肪细胞胰岛素抵抗模型,不同浓度的脂联素球状结构域(globular domain of adiponectin,gAd)干预已经产生胰岛素抵抗的3T3-L1脂肪细胞,葡萄糖氧化酶法检测培养液中葡萄糖的消耗量,实时荧光定量PCR法检测胰岛素受体底物(IRS)-1、磷脂酰肌醇3激酶(PI3K)、蛋白激酶B(PKB)基因水平的变化,Western印迹检测IRS-1酪氨酸磷酸化水平.结果显示,与对照组相比,各实验组葡萄糖消耗量均显著增加(P＜0.01),且随着gAd浓度的增加,葡萄糖消耗量也逐渐增加;500 ng/ml gAd组及1 000 ng/ml gAd组IRS-1、PI3K、PKB的mRNA表达均比对照组显著增加(P＜0.05);同时,gAd可增加3T3-L1脂肪细胞胰岛素抵抗模型IRS-1酪氨酸磷酸化水平,且呈浓度依赖性.提示gAd能够促进3T3-L1脂肪细胞胰岛素抵抗模型葡萄糖的摄取,其机制可能与促进脂肪细胞胰岛素信号转导、改善胰岛素抵抗有关.     

补体C1q／肿瘤坏死因子相关蛋白3对3T3-L1脂肪细胞脂肪因子表达的影响

目的：观察脂肪因子补体C1q/肿瘤坏死因子（TNF）相关蛋白3（CTRP3）对3T3-L1脂肪细胞脂联素（APN）、瘦素（LPT）、内脏脂肪素（VFT）及爱帕琳肽（APL）等脂肪因子表达的调节效应,以及胰岛素抵抗对该调节效应的影响。方法以软脂酸诱导胰岛素抵抗的3 T3-L1脂肪细胞模型,分别以10、50、250μg/L CTRP3干预正常3T3-L1脂肪细胞12以及250μg/L CTRP3干预胰岛素抵抗的3T3-L1脂肪细胞12 h。分别通过酶联免疫吸附法（ ELISA）及实时定量-聚合酶链反应（ RT-PCR）法检测脂肪因子蛋白分泌量及基因表达水平。组间差异采用方差分析,两组间进一步比较采用SNK-q检验。结果250μg/L CTRP3干预正常组APN、LPT、VFT及APL蛋白分泌量较正常对照组分别增加了63.3％、42.9％、57.1％及56.0％（ q＝8.605、8.526、8.284、8.573,均 P＜0.05）;10及50μg/L干预组上述脂肪因子蛋白分泌量呈增加趋势,但除50μg/L CTRP3干预组APL蛋白分泌量较对照组显著增加外[（6.2＆#177;1.1）比（5.0＆#177;0.9）μg/L, q＝4.593,P＜0.05],其余均差异无统计学意义（均P＞0.05）;其基因表达变化趋势与此类似,并且在干预浓度为50μg/L时APN、LPT、VFT及APL mRNA表达水平较正常对照组分别增加22.0％、13.0％、20.0％及33.0％（ q＝6.150、3.987、5.653、9.031,均P＜0.05）。与CTRP3（250μg/L）干预正常脂肪细胞相比,CTRP3（250μg/L）干预胰岛素抵抗脂肪细胞APN、LPT、VFT及APL蛋白分泌量分别降低了28.6％、21.0％、24.5％及17.9％（ q＝6.341、5.969、5.592、4.287,均 P ＜0.05）,基因表达降低了21.6％、17.2％、15.6％及18.9％（q ＝9.225、7.668、7.066、8.210,均P＜0.05）。结论 CTRP3浓度依赖性地增加3T3-L1脂肪细胞APN、LPT、VFT及APL的表达,胰岛素抵抗降低该调节效应。     

软脂酸制备3T3-L1脂肪细胞胰岛素抵抗模型的方法

目的 用软脂酸(PA)诱导3T3-L1脂肪细胞,探讨用PA制备3T3-L1脂肪细胞胰岛素抵抗(IR)模型的方法.方法 将3T3-L1前脂肪细胞诱导分化为成熟的脂肪细胞,用油红O染色法鉴定细胞.用不同浓度的PA(0 mmol/L、0.25 mmol/L、0.5mmol/L、1.0 mmol/L)干预3T3-L1脂肪细胞24 h,收集各组细胞培养液,用葡萄糖氧化酶法测定各组细胞培养液葡萄糖的含量,观察PA对3T3-L1脂肪细胞糖摄取的影响.结果 0.25 mmol/L PA就可明显抑制成熟的3T3-L1脂肪细胞葡萄糖的摄取(P＜0.01),且呈浓度依赖性.与对照组相比,0.25 mmol/L PA组、0.5 mmol/L PA组、1.0 mmol/L PA组葡萄糖摄取率分别下降5.25％、10.29％、14.54％.结论 在胰岛素刺激下,0.25 mmol/L PA作用于3T3-L1脂肪细胞24 h就可诱导细胞产生IR,且随着浓度的增加其效果逐渐增强.     

性激素对3T3-L1脂肪细胞Visfatin表达的影响

目的 观察雌二醇、睾酮和孕酮对3T3-L1脂肪细胞Visfatin mRNA和蛋白表达的影响.方法 10-8mol/L～ 10-6 mol/L 雌二醇、睾酮或孕酮作用于3T3-L1成熟脂肪细胞和前脂肪细胞,孵育过夜后收集细胞,分别采用RT-PCR和Westem blot检测Visfatin mRNA和蛋白的表达情况.结果 在3T3-L1成熟脂肪细胞,与对照组相比,雌二醇和睾酮分别使Visfatin mRNA表达增加24％(1.74±0.31比1.40 ±0.18,P＜0.05)和28％(1.65±0.90比1.29±0.69,P＜0.05);而孕酮不影响成熟脂肪细胞Visfatin mRNA表达.雌二醇轻度增加成熟脂肪细胞Visfatin蛋白表达,但无统计学差异;10-6 mol/L睾酮使成熟脂肪细胞Visfatin蛋白表达增加134％(0.61±0.40比0.26±0.05,P＜0.05).与雌二醇和睾酮不同,孕酮使成熟脂肪细胞Visfatin蛋白表达下调32％(0.19±0.02比0.28±0.02,P＜0.05).在前脂肪细胞,与对照组相比,10-7 mol/L和10-6mol/L雌二醇使Visfatin mRNA表达增加70％(1.04±0.38比0.61±0.16,P＜0.01)和123％(1.36±0.41比0.61±0.16,P＜0.01);睾酮使Visfatin mRNA表达增加76％(1.02±0.24比0.58±0.36,P＜0.05);孕酮使前脂肪细胞Visfatin mRNA表达增加2.6倍(1.53±1.01比0.42 ±0.14,P＜0.05).结论 性激素通过促进或抑制脂肪细胞Visfatin基因或蛋白的表达,参与调节上述激素引起的脂肪细胞胰岛素抵抗的病理生理过程.     

游离脂肪酸刺激核因子NF-kBp65核转位诱导3T3-L1脂肪细胞胰岛素抵抗的分子机制

目的:研究游离脂肪酸对3T3-L1脂肪细胞核因子NF-kBp65表达及转位的影响,探讨游离脂肪酸诱导胰岛素抵抗的分子机制.方法:诱导成熟的3T3-L1脂肪细胞与0.3,0.5,1.0 mmol/L的软脂酸(PA)培养6-24h,用葡萄糖氧化酶法检测培液中的葡萄糖消耗量,以2-脱氧-[~3H]-D-葡萄糖摄入法观察葡萄糖的转运率,用Western blot检测总NF-kBp65蛋白及核NF-kBp65蛋白的表达,用激光扫描共聚焦(CLSM)对NF-kBp65进行定位显示.0.3-1.0 mmol/L软脂酸作用6-24 h后,3T3-L1脂肪细胞的葡萄糖消耗明显减少(3.03±0.34,2.71±0.36,2.64±0.25 mmol/L),呈时间剂量依赖效应,其作用不需要胰岛素的存在;0.3-1.0 mmol/L软脂酸作用6-24 h显著减少3T3-L1脂肪细胞胰岛素刺激的葡萄糖转运率(64%,33%,32%),呈时间剂量依赖效应;核NF-kBp65蛋白表达明显增加,CLSM显示NF- kBp65核转位增加,但软脂酸对3T3-L1脂肪细胞总NF-kBp65蛋白的表达无明显影响.结论:游离脂肪酸可以诱导胰岛素抵抗,其分子机制可能与FFAs刺激NF-kB的活化转位调节相关基因的表达有关.     

高尿酸诱导3T3-L1脂肪细胞胰岛素抵抗及其机制的研究

目的探究高尿酸血症(HUA)对3T3-L1脂肪细胞IR的影响,并且探讨其分子机制。方法 3T3-L1脂肪细胞先经不同浓度UA单独预处理或与N-乙酰-L-半胱氨酸(NAC)共同预处理后再接受胰岛素刺激,采用CCK-8法检测3T3-L1脂肪细胞活力,采用葡萄糖氧化酶法检测葡萄糖消耗量,采用Western blot检测IRS-1和Akt蛋白磷酸化水平及GluT4蛋白水平。结果 HUA可抑制胰岛素诱导的葡萄糖消耗、Akt磷酸化(Thr308)和IRS-1去磷酸化(Ser307),以及GluT4蛋白表达(P0.05),这些作用可被NAC可阻断(P0.05)。结论 HUA可抑制胰岛素激活的IRS-1/Akt信号通路和GluT4蛋白表达,导致3T3-L1脂肪细胞发生IR。     

黄连素对胰岛素抵抗3T3- L1脂肪细胞脂联素、瘦素、TNF-α和IL-6的影响

目的探讨黄连素对胰岛素抵抗(IR)3T3-L1脂肪细胞脂联素、瘦素、肿瘤坏死因子-α(TNF-α)和白细胞介素6(IL-6)蛋白表达的影响,分析黄连素改善IR的分子机制。方法将3T3-L1脂肪细胞随机分为对照组、IR组、黄连素组,应用地塞米松诱导细胞IR,黄连素组同时加入黄连素。采用葡萄糖氧化酶法测定3组细胞上清液葡萄糖消耗量,观察黄连素对脂肪细胞葡萄糖摄取的影响;应用免疫印迹试验测定脂肪细胞脂联素、瘦素蛋白水平变化;应用酶联免疫吸附实验检测脂肪细胞TNF-α和IL-6蛋白水平变化。结果与对照组比较,IR组脂联素蛋白表达水平明显下降(P<0.05),瘦素、TNF-α和IL-6蛋白表达水平升高;经黄连素干预后,脂联素蛋白表达水平有一定升高,瘦素、TNF-α和IL-6蛋白表达水平降低,与对照组比较差异有统计学意义(P<0.05)。结论黄连素可能通过增加脂联素蛋白分泌,减少瘦素、TNF-α和IL-6蛋白水平而改善IR。     

游离脂肪酸刺激核因子NF-κBp65核转位诱导3T3-L1脂肪细胞胰岛素抵抗的分子机制

目的:研究游离脂肪酸对3T3-L1脂肪细胞核因子NF-κBp65表达及转位的影响,探讨游离脂肪酸诱导胰岛素抵抗的分子机制.方法:诱导成熟的3T3-L1脂肪细胞与0.3,0.5,1.0 mmol/L的软脂酸(PA)培养6-24 h,用葡萄糖氧化酶法检测培液中的葡萄糖消耗量,以2-脱氧-[3H]-D-葡萄糖摄入法观察葡萄糖的转运率,用Western blot检测总NF-κBp65蛋白及核NF-κBp65蛋白的表达,用激光扫描共聚焦(CLSM)对NF-κBp65进行定位显示.结果:0.3-1.0 mmol/L软脂酸作用6-24 h后,3T3-L1脂肪细胞的葡萄糖消耗明显减少(3.03±0.34,2.71±0.36,2.64±0.25 mmol/L),呈时间剂量依赖效应,其作用不需要胰岛素的存在;0.3-1.0 mmol/L软脂酸作用6-24 h显著减少3T3-L1脂肪细胞胰岛素刺激的葡萄糖转运率(64%,33%,32%),呈时间剂量依赖效应;核NF-κBp65蛋白表达明显增加,CLSM显示NF-κBp65核转位增加,但软脂酸对3T3-L1脂肪细胞总NF-κBp65蛋白的表达无明显影响.结论:游离脂肪酸可以诱导胰岛素抵抗,其分子机制可能与FFAs刺激NF-κB的活化转位调节相关基因的表达有关.     

小檗碱对3T3-L1胰岛素抵抗细胞模型PI-3K p85蛋白表达的影响

目的:研究小檗碱对3T3-L1胰岛素抵抗细胞模型PI-3K p85蛋白表达的影响,探讨小檗碱改善胰岛素抵抗的分子机制.方法:分别以0.5 mmol/L软脂酸与25 mmol/L葡萄糖加0.6 nmmol/L胰岛素诱导3T3-L1脂肪细胞产生胰岛素抵抗,予以小檗碱进行干预,同时以阿司匹林作为阳性对照,以2-脱氧-[3H]-D-葡萄糖摄入法观察葡萄糖的转运率,用Western blot检测PI-3K p85蛋白的表达.结果:0.5 mmol/L软脂酸作用24 h或25 mmol/L葡萄糖加0.6 nmmol/L胰岛素作用18 h分别使3T3-L1脂肪细胞胰岛素刺激的葡萄糖转运抑制67%和60%,Westem blot显示PI-3K p85蛋白表达减少,与正常对照组比较有统计学意义(P<0.01);同时加入小檗碱则可逆转上述效应使P1-3K p85蛋白表达增加,与模型组比较有明显差异(P<0.01),并且PI-3K p85蛋白的表达与小檗碱的剂量和作用时间呈依赖关系.结论:小檗碱可以明显改善游离脂肪酸和高糖诱导的胰岛素抵抗,其分子机制可能与小檗碱提高PI-3K p85蛋白的表达有关.     

苦酸通调方对HepG2细胞胰岛素抵抗模型中IRS-1、PI3K、Akt蛋白表达的影响

目的观察苦酸通调方对HepG2细胞胰岛素抵抗(IR)模型中内胰岛素受体底物(IRS)-1、磷脂酰肌醇3激酶(PI3K)、蛋白激酶B(Akt)信号分子的影响并探讨相关机制。方法通过0.25 mmol/L棕榈酸联合30 mmol/L高糖孵育24 h诱导HepG2 IR细胞模型,予以不同浓度的苦酸通调方(50,100,200μg/ml)。葡萄糖试剂盒检测细胞培养液上清葡萄糖含量,肝糖原试剂盒测定HepG2细胞内肝糖原含量,蛋白免疫印迹法(Western印迹)检测细胞内IRS-1、PI3K、Akt的蛋白表达。结果与模型组相比,苦酸通调方干预后,呈剂量依赖性增加IR HepG2细胞的葡萄糖消耗量及细胞内肝糖原含量(P<0.05),上调IRS-1、PI3K、Akt蛋白磷酸活化水平(P<0.05)。结论苦酸通调方改善2型糖尿病IR作用可能与影响IRS-1、PI3K、Akt蛋白表达相关。     

GLP-1 amplifies insulin signaling by up-regulation of IRbeta, IRS-1 and Glut4 in 3T3-L1 adipocytes

Glucagon-like peptide-1 (7–36) amide (GLP-1) is an insulin secretagogue. Recently, many studies have shown GLP-1 can improve insulin resistance in peripheral tissues. In the present study, we investigated glucose uptake in 3T3-L1 adipocytes in either basal or insulin resistant state and dissected insulin signaling pathway in order to elucidate the molecular mechanisms of GLP-1 mediated improvement of insulin resistance. We found GLP-1 and its long lasting analogue, exendin 4 up-regulated basal IR, IRS-1 and Glut 4 expressions although they did not increase basal glucose uptake alone. However, GLP-1 and exendin-4 increased insulin mediated glucose uptake in intact and TNF-α treated 3T3-L1 adipocytes by up-regulation of phophorylated IRβ, IRS-1, Akt and GSK-3β. These results indicate that GLP-1 and its analogue exendin-4 can amplify insulin signaling in 3T3-L1 adipocytes by up-regulation of some crucial insulin signaling molecules. Hong Gao and Xinjun Wang equally contributed to this work.     

胰岛素、葡萄糖对3T3-L1脂肪细胞脂肪水孔蛋白表达的调节

利用半定量RT PCR技术及Western印迹法研究胰岛素、葡萄糖对成熟脂肪细胞脂肪水孔蛋白 (AQPap)基因表达的影响。结果表明 ,胰岛素对AQPap的表达具有抑制作用 ;而高浓度葡萄糖则对AQPap的表达具有促进作用     

葡萄糖和胰岛素对3T3-L1脂肪细胞内脏脂肪素mRNA表达的影响

目的研究不同浓度葡萄糖和胰岛素对3T3-L1脂肪细胞中内脏脂肪素（Visfatin）mRNA表达的影响。方法通过real—time RT-PCR方法检测不同浓度葡萄糖和胰岛素培养下3T3-L1脂肪细胞Visfatin mRNA的表达。结果葡萄糖增加了3T3-L1脂肪细胞Visfatin mRNA的表达;胰岛素降低其表达。结论葡萄糖和胰岛素对3T3-L1脂肪细胞中Visfatin mRNA的表达有凋控作用。     

Alterations in insulin signalling pathway induced by prolonged insulin treatment of 3T3-L1 adipocytes

Summary Insulin-induced glucose transport stimulation, which results from the translocation of glucose transporter 4 (GLUT 4)-containing vesicles, is completely blocked after prolonged insulin treatment of 3T3-L1 adipocytes. Since GLUT 4 expression was reduced by only 30%, we looked at the insulin signalling pathway in this insulin-resistant model. Insulin-induced tyrosine phosphorylation of the major insulin receptor substrate IRS 1 was reduced by 50±7%, while its expression was decreased by 70±4%. When cells were treated with wortmannin (a PI3-kinase inhibitor) together with insulin, the expression of IRS 1 diminished to a much lower extent. Associated with the decrease in IRS 1 expression and phosphorylation, the activation by insulin of antiphosphotyrosine immunoprecipitable PI3-kinase activity and of p44^mapk and p42^mapk activities was altered. However, the expression of these proteins was normal and p44^mapk activity remained responsive to the tumour promoter TPA. Those results indicate that prolonged insulin treatment of 3T3-L1 adipocytes induces an insulin-resistant state with a reduced ability of insulin to stimulate the PI3-kinase and the MAP-kinases and a blockade of glucose transporter translocation.Abbreviations GLUT Glucose transporter - TPA tumour promoter - MAPK mitogen-activated protein kinase - IRS insulin receptor substrate - SH2 src homology 2 - GRB GRB: Growth factor Receptor bound protein - PVDF polyvinyliden difluoride - HDM/LDM high density/low density microsomes - MBP myelin basic protein - DMEM Dulbecco's modified Eagle's medium - PMSF phenylmethanesulphonyl fluoride - PI3-kinase phosphatidylinositol 3-kinase     

胰岛素对人肝细胞L02水通道蛋白9表达的影响及其调控通路

Objective To explore the effects of insulin on the expression and the regulatory pathway of AQP9 in normal human liver cells. Methods Normal human liver cells L02 were cultured and treated with PI3K inhibitor LY294002, AKT inhibitor A-443654, MAPK inhibitors SB2030580 and insulin at different concentrations respectively. The AQP9 mRNA and protein expressions were detected with semi-quantitative RT-PCR andWestern blot respectively. Results The insulin (100nmol/L～500nmol/L) treatment decreased the expression of AQP9 in normal human liver cells (P < 0.05) concentration dependency, and the expression of AQP9 began to reduce from 3 hours of insulin stimulation (P < 0.05), especially at insulin treatment for 12 hours (P < 0.05); Incubated with the selective inhibitor of PI3K(LY294002) and AKT(A-443654), the inhibitory effects of insulin on AQP9 expression decreased (P < 0.05); but it did not change significantly by blocking the MAPK signaling pathway. Conclusion The insulin treatment inhibited the expression of AQP9 and the PI3K/akt signal transduction pathwsy was involved in the mechanism.     

胰岛素对人肝细胞L02水通道蛋白9表达的影响及其调控通路

Objective To explore the effects of insulin on the expression and the regulatory pathway of AQP9 in normal human liver cells. Methods Normal human liver cells L02 were cultured and treated with PI3K inhibitor LY294002, AKT inhibitor A-443654, MAPK inhibitors SB2030580 and insulin at different concentrations respectively. The AQP9 mRNA and protein expressions were detected with semi-quantitative RT-PCR andWestern blot respectively. Results The insulin (100nmol/L～500nmol/L) treatment decreased the expression of AQP9 in normal human liver cells (P < 0.05) concentration dependency, and the expression of AQP9 began to reduce from 3 hours of insulin stimulation (P < 0.05), especially at insulin treatment for 12 hours (P < 0.05); Incubated with the selective inhibitor of PI3K(LY294002) and AKT(A-443654), the inhibitory effects of insulin on AQP9 expression decreased (P < 0.05); but it did not change significantly by blocking the MAPK signaling pathway. Conclusion The insulin treatment inhibited the expression of AQP9 and the PI3K/akt signal transduction pathwsy was involved in the mechanism.     

Determinants of daily insulin use in Type 1 diabetes

OBJECTIVE: Insulin need for a given degree of glucose control varies markedly among individuals. We examined which factors determine daily insulin use in patients with Type 1 diabetes. METHODS: A cross-sectional study was performed in 416 patients. Clinical parameters, medication use, physical activity, smoking, alcohol consumption, and laboratory parameters were determined. RESULTS: Body mass index and waist circumference were positively related to daily insulin use (2.3 U/kg/m(2), 95% CI=1.9-2.7 and 0.8 U/cm, 95% CI=0.6-0.9, adjusted for age and sex). Age, female sex, and duration of diabetes were inversely related to daily insulin dose. There was an increase of 3.6 U of insulin per mmol/l triglycerides (95% CI=1.04-6.2) and a decrease of 5.9 U of insulin per mmol/l high-density lipoprotein cholesterol (95% CI=-10.0 to -1.8), adjusted for age, sex, and weight. For blood pressure-lowering drugs, the strongest relation was found for thiazide diuretics (difference of 7.1 U insulin/day, 95% CI=0.2-14.2, adjusted for age, sex, and weight). The use of an insulin pump and physical activity were related to lower daily insulin need: -8.7 U/day (95% CI=-11.8 to -5.5) and -1.7 U/day per activity score unit (95% CI=-3.2 to -0.2), respectively, adjusted for age, sex, and weight. Smoking was related to an increased need of 5.3 U/day (95% CI=1.5-9.0), adjusted for age, sex, and weight. CONCLUSIONS: Our results show that components of the metabolic syndrome are positively related to daily insulin use. Also, decreased physical activity, smoking, and the use of blood pressure-lowering drugs, which influence insulin sensitivity, are associated with an increased insulin need. These findings suggest that the presence of insulin resistance in Type 1 diabetes or "double diabetes" plays a key role in determining daily insulin need.     

Epigallocatechin-3-O-gallate (EGCG) attenuates FFAs-induced peripheral insulin resistance through AMPK pathway and insulin signaling pathway in vivo

We aimed to investigate the effects and possible mechanisms of Epigallocatechin-3-O-gallate (EGCG) on free fatty acids (FFAs)-induced peripheral insulin resistance in vivo. Overnight-fasted Wistar rats were subjected to 48-h intravenous infusion of either saline or Intralipid plus heparin (IH) with or without different doses of EGCG co-injection. Hyperinsulinemic-euglycemic clamp was performed in awake rats to assess peripheral insulin sensitivity. Co-injection with EGCG significantly prevented FFAs-induced peripheral insulin resistance, decreased plasma markers of oxidative stress: malondialdehyde (MDA) and 8-isoprostaglandin, and increased antioxidant enzymes: superoxide dismutases (SOD) and Glutathione peroxidase (GPx). Furthermore, EGCG treatment reversed IH-induced: (1) decrease in Thr172 phosphorylation of AMP activated protein kinase (AMPK); (2) increase in protein kinase Cθ(PKCθ) membrane translocation and Ser307 phosphorylation of insulin receptor substrate-1 (IRS-1); (3) decrease in Ser473 phosphorylation of Akt and Glucose transporter 4 (GLUT4) translocation in skeletal muscle and adipose tissue. Our data suggest that EGCG treatment ameliorated FFAs-induced peripheral insulin resistance in vivo, and this might be through decreasing oxidative stress and PKCθ membrane translocation, activating the AMPK pathway and improving insulin signaling pathway in vivo. This study suggests the therapeutic value of EGCG in protecting from insulin resistance caused by elevated FFAs.