LITAF基因对脂肪酸诱导HPA-v细胞胰岛素抵抗的影响

目的:通过RNA干扰技术特异性抑制LITAF基因,观察HPA-v人前脂肪细胞胰岛素信号通路的变化情况.方法:将HPA-v人前脂肪细胞和THP-1源巨噬细胞共培养,分为3组,分别为阴性对照组(Scramble组)、siRNA组和正常对照组(NC组),通过qRT-PCR,Western blot法检测LITAF,IRS-2,p-PKC,PI3-K及GLUT2的表达.结果:在软脂酸的刺激下Scramble组LITAF的表达较高于LITAF siRNA和IVC组;IRS-2,p-PKC,PI3-K及GLUT2在LITAF RNAi组较NC组和Scramble组明显提高(P＜0.05).结论:LITAF参与了软脂酸引起的脂肪细胞胰岛素抵抗,而脂肪酸作用于巨噬细胞的受体TLR4同样也是LITAF通路的细胞膜受体,软脂酸减弱了对胰岛素信号通路分子的抑制作用,因此LITAF参与胰岛素抵抗对糖尿病的发病起了至关重要的作用.     

visfatin对体外脂肪细胞胰岛素受体底物和PI3K表达的影响

目的：从胰岛素经典信号传导通路磷脂酰肌醇-3-激酶（PI3K）角度探讨内脏脂肪素（visfatin）与2型糖尿病（T2DM）胰岛素抵抗（IR）的关系。方法：复苏、传代和诱导分化人源T2DM前脂肪细胞,构建 visfatin过表达载体,进行载体转化、培养和提取;以4个不同表达梯度（0.0、1.0、2.5和5.0 μg）转染传代脂肪细胞,以0.0 μg组为对照组,其余3组为观察组;Q-PCR法检测visfatin 、胰岛素受体底物1（IRS-1）、胰岛素受体底物2（IRS-2）和 PI3K（P85α） mRNA表达水平,Western blotting法检测visfatin、IRS-1、IRS-2和PI3K（P85α） 蛋白表达水平及IRS-1和IRS-2酪氨酸磷酸化水平,[³H]-2-脱氧-D-葡萄糖摄取法测定细胞葡萄糖摄取率的变化。结果：各组 visfatin mRNA及蛋白表达水平随转染浓度梯度升高而升高（P<0.01）,所构建visfatin过表达载体有效。随visfatin表达增加,各组IRS-1和PI3K（P85α） mRNA和蛋白表达水平以及IRS-1磷酸化程度均明显升高（P< 0.01）,但IRS-2 mRNA和蛋白表达水平未出现明显变化（P>0.05）。脂肪细胞的葡萄糖摄取率随visfatin表达增加而升高（P<0.05）。结论：体外脂肪细胞visfatin过表达可增加IRS-1和PI3K的表达水平。     

芪蛭降糖胶囊对糖尿病大鼠胰岛素抵抗的作用及其机制

目的：探讨芪蛭降糖胶囊(QJ)对糖尿病大鼠胰岛素抵抗(IR)的作用,阐明其药物作用的分子药理机制。方法：100只Wistar大鼠采用高脂饮食联合注射链脲佐菌素（STZ）的方法复制2型糖尿病大鼠模型。将建模成功大鼠随机分为模型组（DM）,参芪降糖颗粒阳性对照组（SQ）,芪蛭降糖胶囊低（QJL）、中 (QJM)和高剂量组(QJH),同时设立正常对照组（NC）。芪蛭降糖胶囊低、中和高剂量组药物浓度分别为0.34、0.68和1.35 g?kg-1;参芪降糖颗粒药物浓度为0.27 g?kg-1。大鼠建模成功后,给予相应浓度药物干预治疗8周。经药物干预后,应用血糖检测仪及全自动生化分析仪测定大鼠空腹血糖（FBG）、空腹胰岛素（FINS）、胰岛素抵抗指数（IRI）和脂质代谢相关生化指标,Real Time PCR法测定肝脏组织中胰岛素受体底物1（IRS-1）、磷脂酰肌醇-3激酶（PI3K）和葡萄糖转运体4（GLUT4）基因的mRNA表达水平,ELISA法测定血清肿瘤坏死因子α（TNF-α）和脂联素（ADPN）水平。结果：与正常对照组比较,模型组大鼠FBG、FINS和IRI显著升高（P<0.05或P<0.01）;血清总胆固醇（TC）、甘油三酯（TG）和低密度脂蛋白（LDL）水平显著升高（P<0.05）,血清高密度脂蛋白（HDL）水平显著降低（P<0.05）;肝脏组织中IRS-1、PI3K和GLUT4基因的mRNA表达水平显著下降（P<0.05）,血清TNF-α水平显著升高（P<0.05）,血清ADPN水平显著降低（P<0.05）。与模型组比较,芪蛭降糖胶囊低、中、高剂量组及参芪降糖颗粒阳性对照组大鼠FBG和IRI显著降低（P<0.01）;芪蛭降糖胶囊中、高剂量组及参芪降糖颗粒阳性对照组FINS显著降低（P<0.05）;芪蛭降糖胶囊中剂量组及参芪降糖颗粒阳性对照组血清TC、TG和LDL水平显著降低（P<0.05或P<0.01）,HDL水平显著升高（P< 0.05）;肝脏组织中IRS-1、PI3K和GLUT4基因的mRNA表达水平显著上调（P<0.05）;芪蛭降糖胶囊中、高剂量组及参芪降糖颗粒阳性对照组血清TNF-α水平显著降低（P<0.05）,血清ADPN水平显著升高（P<0.05）。结论：芪蛭降糖胶囊具有改善糖尿病大鼠IR的作用,其作用机制与改善糖脂代谢、影响胰岛素信号传导通路有关。     

Chronic Hyperinsulinism Induced Down—regulation of Insulin Post—Receptor Signaling Transduction in Hep G2 Cells

Insulin initiates its biological effects first bybinding to its cellular receptor,thereby activatingthe tyrosine kinase in theβ- subunit of the insulinreceptor ( IRβ) .This leads to tyrosine phosphory-lation of several insulin receptor protein substrates( IRS) ,especially IRS- 1 [1,2 ] .Phosphorylated IRS-1 plays a critical role in divergence of the insulinsignal.Phosphorylated IRS- 1 associates with SH2domain proteins,such as the p85 subunit of phos-phatidylinositol 3- kinase ( PI 3-…     

游离脂肪酸引起肝细胞胰岛素抵抗及其机制的研究

目的研究游离脂肪酸（FFA）诱导人肝癌细胞（HepG2）引起胰岛素抵抗及其分子机制.方法应用含0.25 mmol/L的软脂酸（PA组）或100 nmol/L胰岛素（Ins组）与不含软脂酸和胰岛素（正常组）的DMEM培养基培养HepG2细胞24 h,正常组和PA组中又分加与不加磷酯酰肌醇3激酶（PI3K）抑制剂Wort-mannin两个亚组,100 nmol/L胰岛素刺激后分别测定培养液中的葡萄糖浓度、细胞内的糖原含量、磷酸烯醇式丙酮酸羧激酶（PEPCK）活性及胰岛素受体底物2（IRS-2）的蛋白水平.结果PA组和Ins组培养液中葡萄糖含量显著高于正常组（P＜0.01）,而细胞内糖原含量显著减少（P＜0.01）;PA组胰岛素刺激的PEPCK活性显著高于正常组（P＜0.01）,IRS-2蛋白水平显著低于正常组（P＜0.01）.无论应用Wortmannin处理与否,PA组中的PEPCK活性及IRS-2蛋白水平差异无显著性（P＞0.05）,而正常组中PEPCK活性及IRS-2蛋白水平的差异有显著性（P＜0.01）.结论加0.25 mmol/L的软脂酸培养24 h后,肝细胞可能由于胰岛素信号转导障碍产生胰岛素抵抗;胰岛素抵抗的形成可能与IRS-2及PI3K相关分子缺陷有关.     

ELK1调控PI3K/Akt信号通路促进骨肉瘤细胞增殖及其机制研究

目的 探讨E26转录因子1(ELK1)调控PI3K/Akt信号通路对骨肉瘤细胞增殖能力的影响及其发挥作用的可能机制。方法 Western blotting检测ELK1在骨肉瘤细胞系U2OS、MG-63、HOS及正常成骨细胞hFOB11.9中的相对表达量;选择相对表达量最高的骨肉瘤细胞系进行ELK1 siRNA转染,分为si-NC组、si-ELK1-1组和si-ELK1-2组;MTS检测各组细胞增殖率;平板克隆实验检测各组细胞克隆形成能力;Western blotting检测各组细胞中PI3K/Akt信号通路关键蛋白pPI3K和pAKT的相对表达量;采用PI3K/Akt信号通路激活剂SC79与ELK1 siRNA同时处理骨肉瘤细胞后MTS法检测各组细胞增殖率,平板克隆实验检测各组细胞克隆形成能力。结果 与正常成骨细胞比较,ELK1在骨肉瘤细胞系中的相对表达量均升高（P <0.05）,在U2OS细胞中的相对表达量最高（P <0.05）;U2OS细胞转染ELK1 siRNA,Western blotting结果显示,与si-NC组比较,si-ELK1-1组、si-ELK1-2组U...     

黄芪多糖对2型糖尿病大鼠肾组织胰岛素信号转导的影响

目的:研究黄芪多糖(APS)对 2 型糖尿病大鼠肾组织胰岛素信号分子表达的影响。方法:Wistar大鼠随机分成正常对照组(Control组)、链脲佐菌素(STZ)糖尿病组(DM组)和糖尿病黄芪多糖治疗组(DM+APS组),5周后观察动物一般情况,处死动物取血测血糖、血清胰岛素水平,用免疫组化的方法检测肾组织中胰岛素受体(InsR)、胰岛素受体底物 1(IRS 1)、磷脂酰肌醇3 激酶(PI3K)表达水平。结果:DM组体重水平高于 Control组和DM+APS组,差别有显著性(P<0.01);DM组和DM+APS组血糖水平均高于 Control组(P<0.01),DM+APS组血糖水平低于DM组(P<0.01);各组间血胰岛素水平差别无显著性(P> 0. 05); DM组肾组织 InsR、IRS 1、PI3K的表达水平均低于Control组和DM+APS组(P<0.05)。结论:黄芪多糖可降低 2 型糖尿病大鼠血糖水平,其机制可能与提高糖尿病大鼠肾组织中 InsR、IRS 1、PI3K水平,增加组织对胰岛素的敏感性,改善胰岛素信号转导有关。     

大黄素介导IRS-2/PI3K/Akt通路干预大鼠非酒精性脂肪性肝炎的实验研究

目的探讨大黄素通过介导IRS-2/PI3 K/Akt通路对非酒精性脂肪性肝炎(NASH)的影响。方法随机选取25只雄性大鼠给予高脂饲料喂养12周制备NASH模型,12周后取5只大鼠进行检测,确定NASH模型制备成功,剩余20只大鼠数字表法随机分为模型组(10只)和大黄素组(10只),另取同龄10只雄性未造模大鼠作为正常对照组。大黄素组大鼠给予20 mg/kg的大黄素灌胃,正常对照组和模型组给予等量生理盐水,连续给予8周。对大鼠肝脏进行称重,计算肝指数;检测空腹血糖和空腹胰岛素,计算胰岛素抵抗指数(HOMA-IR),检测血生化指标。对肝组织进行HE染色,检测肝组织中IRS-2、p-IRS-2、PI3K、p-PI3K、Akt、p-Akt蛋白相对表达量。结果模型组大鼠肝指数、空腹血糖、空腹胰岛素、HOMA-IR、ALT、AST、TG、TC和LDL-C水平较正常对照组增高,HDL-C水平较正常对照组降低(P<0.01);大黄素组大鼠肝指数、空腹血糖、空腹胰岛素、HOMA-IR、ALT、AST、TG、TC和LDL-C水平较模型组降低,HDL-C水平较模型组增高(P<0.05)病理检测发现,模型组出现大量脂肪变性,存在炎性细胞浸润和细胞气球样变性,大黄素组病灶明显较模型组减轻。模型组大鼠IRS-2、p-IRS-2、PI3K、p-PI3K、Akt、p-Akt蛋白相对表达量较正常对照组降低(P<0.05),大黄素组大鼠IRS-2、p-IRS-2、PI3K、p-PI3K、Akt、p-Akt蛋白相对表达量较模型组增高(P<0.05)。结论大黄素可以提高IRS-2/PI3K/Akt通路的活性,改善高脂诱导的NASH大鼠肝脏脂肪沉积及胰岛素抵抗。     

氯沙坦改善3T3-L1脂肪细胞胰岛素抵抗的机制研究

目的探讨氯沙坦改善3T3-L1脂肪细胞胰岛素抵抗的主要作用机制。方法以地塞米松诱导3T3-L1脂肪细胞,建立胰岛素抵抗细胞模型,根据细胞模型添加干预药物的不同分为模型对照组（不添加任何药物）、氯沙坦组（分别给予1、10、100μmol/L氯沙坦干预48 h）和wortmannin＋氯沙坦组,wortmannin＋氯沙坦组以100 nmol/L的磷脂酰肌醇3激酶（PI3K）特异性抑制剂wortmannin预处理20 min后再加入100μmol/L氯沙坦干预48 h。观察脂肪细胞体积的变化,采用葡萄糖氧化酶法检测细胞培养上清液中葡萄糖的浓度,采用Western blotting分析脂肪细胞中PI3K和胰岛素受体底物1（IRS-1）的表达以及IRS-1丝氨酸磷酸化水平。结果与模型对照组比较,氯沙坦组脂肪细胞体积明显缩小（P〈0.01）,细胞培养上清液中葡萄糖的浓度显著降低（P〈0.01）,PI3K和IRS-1表达明显上升（P〈0.01）,IRS-1丝氨酸磷酸化水平显著下降（P〈0.01）但可被wortmannin阻断。结论氯沙坦可使3T3-L1脂肪细胞胰岛素抵抗模型的细胞体积缩小,并增加细胞对葡萄糖的利用,其机制可能与PI3K信号通路有关。     

Effect of Electro-acupuncture on Expression of IRS-1/PI3K/GLUT4 Pathway in Ovarian Granulosa Cells of Infertile Patients with Polycystic Ovary Syndrome-Insulin Resistance of Phlegm-Dampness Syndrome

Objective: To evaluate the effect of electro-acupuncture (EA) in infertile patients with phlegm dampness polycystic ovary syndrome-insulin resistance (PCOS-IR). Methods: Seventy-six PCOS-IR patients who underwnet in vitro fertilization and embryo transfer (IVF-ET) were equally assigned to two groups according to a random digital table: the EA group and the control group, with 38 cases in each group. Before undergoing IVF, the two groups were treated with EA or pseudo-acupuncture, respectively, for 3 menstrual cycles. The intervention was 25 min twice a week until the day of oocyte collection. The selected acupoints were Zhongwan (RN 12), Tianshu (ST 25), Daheng (SP 15), Daimai (GB 26), Qihai (CV 6), Guanyuan (CV 4), and bilateral points including Xuehai (SP 10), Fenglong (ST 40), Zusanli (ST 36), and Yinlingquan (SP 9). Evaluation of phlegm-dampness syndrome score and IR score were carried out before and after treatment. Additionally, the number of oocytes retrieved, transplantable embryo rate, high-quality embryo rate, clinical pregnancy rate and live birth rate were compared between the two groups. Real-time polymerase chain reaction analysis was used to monitor the mRNA expression of the insulin receptor substrate (IRS-1), phosphatidylinositiol 3-kinase (PI3K) and glucose transport factor 4 (GLUT4) in ovarian granulosa cells. Results: EA treatment reduced the phlegm-dampness syndrome score as well as the IR scores compared with the control group (P<0.05). No significant differences in the number of oocytes retrieved and clinical pregnancy rate between the two groups (P>0.05). Moreover, the transplantable embryo rate [49.0% (284/580) vs. 41.9% (273/652)], high-quality embryo rate [36.6% (104/284) vs. 27.8% (76/273)], and live birth rate [50% (19/38) vs. 26.3% (10/38)] in the EA group were significantly higher than in the control group (P<0.05). Gene expression analyses revealed significantly elevated IRS-1, PI3K and GLUT4 mRNA in ovarian granulosa cells of the EA group compared with the control group (P<0.05). Conclusions: EA may ameliorate the effects of phlegm-dampness syndrome and ovarian IR in PCOS-IR patients. Mechanistically, this effect might be through an upregulation of the IRS-1/PI3K/GLUT4 signaling pathway, which may result in improved oocyte quality and embryonic development potential. (Registration No. ChiCTR1800015453)     

Genistein reverses free fatty acid-induced insulin resistance in HepG2 hepatocytes through targeting JNK

This study investigated the effects and molecular mechanisms of genistein in improving insulin resistance induced by free fatty acids (FFAs) in HepG2 hepatocytes. A model of insulin resistance in HepG2 cells was established by adding palmitic acid (0.5 mmol/L) to the culture medium and the cells were treated by genistein. Glucose consumption of HepG2 cells was determined by glucose oxidase method. The levels of c-jun N-terminal kinase (JNK) phosphorylation, insulin receptor substrate-1 (IRS-1) Ser307 phosphorylation, JNK, IRS-1, phosphatidylinositol-3-kinase p85 (PI-3K p85) and glucose transporter 1 (GLUT1) proteins were detected by Western blotting. The results showed that after the treatment with palmitic acid for 24 h, the insulin-stimulated glucose transport in HepG2 cells was inhibited, and the glucose consumption was substantially reduced. Meanwhile, the expressions of IRS-1, PI-3K p85 protein and GLUT1 were obviously reduced, while the levels of JNK phosphorylation and IRS-1 Ser307 phosphorylation and the expression of JNK protein were significantly increased, as compared with cells of normal control. However, the aforementioned indices, which indicated the existence of insulin resistance, were reversed by genistein at 1-4 μmol/L in a dose-dependent manner. It was concluded that insulin resistance induced by FFAs in HepG2 hepatocytes could be improved by genistein. Genistein might reverse FFAs-induced insulin resistance in HepG2 cells by targeting JNK.     

解偶联蛋白2基因表达与胰岛β细胞分泌功能的关系及机制

目的 观察长期高脂饮食对大鼠胰岛β细胞胰岛素分泌功能的影响,探讨解偶联蛋白2(UCP2)及相关的氧化应激在其中的作用及机制.方法 8周龄SD大鼠随机分为正常饲料组(NC组,20只)和高脂饲料组(HF组,20只).饲养20周检测以下指标:(1)血浆硝基酪氨酸,丙二醛(MDA)和还原型谷胱甘肽(GSH)水平;(2)正常血糖高胰岛素钳夹试验,评价外周组织胰岛素抵抗程度;(3)胰岛细胞表面灌注试验,评价离体胰岛β细胞动态分泌功能;(4)实时荧光定量PCR方法比较两组大鼠胰岛细胞胰岛素受体底物-1(IRS-1)、胰岛素受体底物-2(IRS-2)以及UCP2mRNA表达的变化.(5)免疫组织化学染色及图像分析检测IRS-1,IRS-2在两组大鼠胰岛中的表达.结果 (1)HF组血浆硝基酪氨酸(0.17±0.01)μmol/L和MDA(22±5)nmol/L水平高于NC组(0.14±0.02)μmol/L,(13±3)nmol/L,(P均＜0.05),GSH水平(103±9)mg/ml明显低于NC组(142±9)mg/l,(P＜0.01);(2)HF组葡萄糖输注率(GIR)较Nc组明显降低(P＜0.01);HF组葡萄糖刺激的胰岛素分泌(GSIS)功能明显下降(P＜0.01);(3)HF组胰岛细胞IRS-1及IRS-2mRNA表达分别降低42.3%、28.1%,UCP2表达增高32.5%(P均＜0.05).(4)HF组胰岛IRS-1和IRS-2的表达较对照组分别降低26.3%(P＜0.05)和11.2%(P＞0.05).(5)UCP2与胰岛细胞IRS-1 mRNA表达呈负相关(r=-0.621,P＜0.05);且与IRS-2mRNA表达也呈负相关(r=-0.416,P＜0.05).结论 长期高脂饲养能导致大鼠胰岛细胞胰岛素信号分子表达下降,β细胞胰岛素分泌功能受损,具体机制推测与UCP2相关的氧化应激增强有关.     

黄芪甲苷对糖尿病大鼠肝损伤保护作用及其机制研究

目的 探讨黄芪甲苷(AS-Ⅳ)对糖尿病大鼠肝脏损伤的保护作用及其可能机制.方法 采用腹腔注射链脲佐菌素诱导建立糖尿病大鼠模型.将造模成功的糖尿病大鼠随机分为对照组、模型组、罗格列酮组(1.25 mg/kg)、AS-Ⅳ组(20、40、80 mg/kg).连续灌胃给药6周,于给药前测空腹血糖,处死,取肝脏,称肝湿重,计算肝脏指数;采用ELISA法测定各组大鼠血清中丙氨酸氨基转移酶(ALT)、天门冬氨酸氨基转移酶(AST)活性;试剂盒检测肝脏组织中谷胱甘肽过氧化物酶(GSH-Px)、总超氧化物歧化酶(T-SOD)和丙二醛(MDA)含量变化;HE染色观察肝组织病理形态学变化;免疫组化法检测肝脏组织中胰岛素受体底物2(IRS-2)的表达;Western blot法检测磷脂酰肌醇-3-激酶(PI3K)、磷酸化蛋白激酶B(p-AKT)和葡萄糖转运蛋白4(GLUT4)的表达水平.结果 与对照组相比,模型组大鼠肝脏指数、空腹血糖、空腹血清胰岛素、血清AST、ALT、三酰甘油、总胆固醇、高密度脂蛋白水平、肝脏组织中MDA含量均明显升高(P＜0.01),T-SOD与GSH-Px降低(P＜0.01),肝病理损伤明显,同时肝组织中IRS-2、PI3K、p-AKT、GLUT4蛋白表达减少.与模型组相比,AS-Ⅳ(20、40、80 mg/kg)组能明显改善上述指标的变化,使肝组织损伤减轻,并增加IRS-2、PI3K、p-AKT、GLUT4蛋白表达.结论 AS-Ⅳ对糖尿病大鼠肝损伤有保护作用,其机制可能与抗氧化、上调肝脏PI3 K/AKT信号通路有关.     

杞丹方对糖尿病小鼠降血糖作用及机制研究

  目的  研究杞丹方对糖尿病小鼠降血糖作用并探讨相关机制。  方法  取SPF级ICR雄性小鼠, 禁食16 h后腹腔注射四氧嘧啶120 mg·kg-1, 5 d后禁食12 h测血糖, 血糖值在10~25 mmol·L-1为糖尿病造模成功。将造模成功的ICR雄性糖尿病小鼠, 分为模型组, 二甲双胍组, 杞丹方低、中、高剂量组(0.34、0.67、1.34 g·kg-1·d-1), 正常ICR雄性小鼠为空白组, 给药30 d。每10 d记录体质量和空腹血糖(FBG)1次, 30 d后进行葡萄糖耐量试验(OGTT); ELISA法检测血清胰岛素水平并摘取胰腺、肝脏组织, 进行HE染色, 观察其病理改变; 采用Western blot和qPCR检测肝脏组织IRS-1、PI3K、AKT和GLUT4的表达水平。  结果  与模型组相比, 杞丹方中、高剂量组小鼠FBG水平、糖耐量显著降低(P < 0.01),血清胰岛素水平显著升高(P < 0.01)。杞丹方各剂量组胰腺和肝脏组织结构有明显改善, 胰岛形态得到一定程度恢复, 少见肝脏组织异常与血管充血。杞丹方高剂量组能显著上调肝脏组织中的p-IRS-1/IRS-1、p-PI3K/PI3K、p-AKT/AKT和GLUT4蛋白表达水平(P < 0.01);显著上调肝脏组织中的IRS-1、PI3Kp85α、AKT1和GLUT4 mRNA水平(P < 0.01)。  结论  杞丹方对糖尿病小鼠具有降血糖作用, 其作用机制是通过调控IRS-1/PI3K/AKT信号通路来实现的。      

Relationship between islet beta cell dysfunction and gene expression of uncoupling protein-2 and possible mechanism thereof

OBJECTIVE: To study the effects of high fat diet on the functions of islet beta cells and the role of uncoupling protein-2 (UCP2) therein and possible mechanism. METHODS: Forty SD rats were randomly divided into two equal groups: high-fat-(HF) diet group, fed with HF diet for 20 weeks, and normal diet control (NC) group, fed with normal diet. At the end of the twentieth week blood samples were collected from the heart to determine the serum fasting blood glucose (FBG) and fasting insulin (FINS), and plasma nitrotyrosine, malondialdehyde (MDA), and glutamylcysteinylglycine (GSH), indicators of oxidative stress. Glucose infusion rate (GIR) was measured using euglycemic hyperinsulinemic clamp test to evaluate the peripheral insulin resistance. Pancreatic islets were isolated and collected. Islet perfusion was conducted to evaluate the insulin secretion in the islet beta cells. Real-time PCR was used to detect the expression of insulin receptor substrate-1 (IRS-1), IRS-2, and uncoupling protein 2 (UCP2) genes in the islet. Immunohistochemistry was used to detect the protein expression of IRS-1 and IRS-2. RESULTS: (1) The concentrations of plasma nitrotyrosine and MDA of the HF group were both significantly higher than those of the NC group (both P < 0.05). However, the plasma GSH of the HF group was significantly lower than that of the NC group (P < 0.01). (2) The blood glucose of both groups became stable since 60 min after the experiment and the GIR of the HF group was (5.25 +/- 1.2) mg x min(-1) x kg(-1), significantly lower r than that of the NC group [(13.6 +/- 1l.7) mg x min(-1) x kg(-1), P < 0.01). (3) The peak of glucose-stimulated insulin secretion (GSIS) of the HF group was significantly lower than that of the NC group; and the GSIS peak increase In comparison with the NC group. (4) In comparison with the NC group, the mRNA expression levels of IRS-1 and IRS-2 genes of the HF group were significantly lower, by 42.3% and 28.1% respectively (both P < 0.05), and the expression of UCP2 was significantly higher, by 32.5% (P < 0.05). (5) Compared with the NC group, the protein expression levels of IRS-1 and IRS-2 in the islets of the HF group were lower, by 26.3% and 11.2% respectively, however not significantly (both P > 0.05). (6) There was a significantly negative correlation between the UCP2 and IRS-1/IRS-2 gene expression in islet beta cells in the HF group (r = -0.621 and r = -0.436, both P < 0.05). CONCLUSION: High-fat-diet impairs the expression of insulin signal transduction molecules and the function of islet beta cells that may be correlated with overexpression of UCP2. The basic insulin secretion of HF group was significantly higher than that of the NC group; but the glucose-stimulated insulin secretion (GSIS) peak decreased in comparison with the NC group. Compared with the NC group, the protein expression levels of IRS-1 and IRS-2 in the islets of the HF group were lower, by 26.3% (P < 0.05) and 11.2% (P > 0.05) respectively.     

Leptin Regulated Insulin Secretion via Stimulating IRS2-associated Phosphoinositide 3-kinase Activity in the isolated Rat Pancreatic Islets

Leptin,theproductofob gene,isa peptidehor-mone secreted by adipocytes thatacts in the hypotha-lamus and playsa centralrole in regulation of feedingbehavior and energy homeostasis[1] .It has recentlybeen confirmed that leptin receptor(OB- R) m RNAand protein were expressed in rat pancreaticβ- cells,indicating thatleptin may directly regulate insulin se-cretion.Several groups have addressed this question,but the results were controversial[2 ,3] .Up to now,the molecular mechanism by which lept…     

Effects of glucose and insulin on the H9c2 （2-1） cell proliferation may be mediated through regulating glucose transporter 4 expression

Background The change of glucose transporter 4 （GLUT4） expression could influence glucose uptake in the myocardial cells and then effect myocardial metabolism, which maybe one of the factor for the diabetes cardiovascular disease. This study aimed to explore the influence of glucose and insulin at different concentrations on H9c2 （2-1） cell proliferation and its GLUT4 expression in vitro, and evaluate the correlation between myocardial cells proliferation and GLUT4 expression. This might be helpful for understanding the relationship between glucose metabolism and cardiovascular disease. Methods According to glucose concentrations in culture medium, cultured H9c2 rat myocardial cells were divided into five groups： control group （NC, glucose concentration 5.0 mmol/L）, low glucose group （LG, glucose concentration 0.1 mmol/L）, high glucose group 1 （HG1, glucose concentration 10 mmol/L）, high glucose group 2 （HG2, glucose concentration 15 mmol/L）, high glucose group 3 （HG3, glucose concentration 20 mmol/L）. Then according to different insulin concentrations in culture medium, each group was further divided into two subgroups： normal insulin subgroup （INSc, insulin concentration 3.8 mU/L）, high insulin subgroup （INSh, insulin concentration 7.6 mU/L）. H9c2 （2-1） cells were cultured for 1, 2, 3 days, the proliferation of cells were assayed by cell counting Kit-8 assay, the expressions of GLUT4 mRNA and protein were detected with RT-PCR and Western Blotting technique, and the relation between myocardial cells proliferation and GLUT4 expression was evaluated.     

大剂量抗氧化剂对高脂饲养大鼠胰岛β细胞分泌功能的影响及机制

目的:探讨大剂量抗氧化剂-N-乙酰半胱氨酸(N-acetyl-l-cysteine,NAC)对高脂饲养大鼠胰岛β细胞分泌功能的影响及可能机制。方法:将59只8周龄SD大鼠随机分为正常饲料组(NC组)、高脂饲料组(HF组)和高脂 NAC组(NAC组)。饲养20周,(1)测血浆及胰腺组织丙二醛(MDA)和还原型谷胱甘肽(GSH)水平;(2)正常血糖高胰岛素钳夹实验,评价外周组织胰岛素抵抗程度;(3)胰岛细胞表面灌注实验,评价离体胰岛β细胞动态分泌功能;(4)实时荧光定量PCR方法比较各组大鼠胰岛素受体底物-1(IRS-1)、胰岛素受体底物-2(IRS-2)和葡萄糖转运子-2(Glut-2)mRNA表达的变化。结果:(1)HF组血浆及胰腺MDA水平明显高于NC组,GSH水平低于NC组,NAC可以改善以上变化;(2)HF组葡萄糖输注率(GIR)比NC组降低(P<0.01),用NAC后GIR明显改善(P<0.01);HF组葡萄糖刺激的胰岛素分泌(GSIS)功能下降,用NAC后可逆转上述变化;(3)HF组胰岛细胞IRS-1、IRS-2、Glut-2mRNA表达降低42.3%、28.1%、22.9%(P均<0.05);NAC组胰岛细胞IRS-1、IRS-2、Glut-2 mRNA表达与HF组相比增加40.2%、30.2%,19.1%(P均<0.05)。结论:大剂量抗氧化干预治疗能改善胰岛细胞胰岛素信号传导,逆转高脂饲养导致的大鼠胰岛细胞分泌功能紊乱,其机制可能与NAC纠正机体氧化及抗氧化失衡有关。     

胰岛素信号转导基因表达的改变与α细胞胰岛素抵抗的实验研究

目的探讨高脂喂养及大剂量链脲佐菌素(STZ)去β细胞处理的肥胖大鼠胰岛α细胞信号转导通路分子的表达情况及其可能机理。方法 30只 SD 大鼠分为高脂饲料喂养的肥胖(HF)组和普通饲料喂养的正常对照(NC)组。喂养20周后,(1)检测空腹血胰岛素(Ins)、胰高糖素(Glc)、游离脂肪酸(FFA)、甘油三酯(TG)水平。(2)正常血糖高胰岛素钳夹试验评价外周胰岛素抵抗程度(NC 组7只,HF 组7只)。(3)NC 组和 HF 组各8只,给予大剂量链脲佐菌素(STZ)去β细胞处理,即 NC-B 组,HF-B 组。使用胰岛素控制血糖,5d 后处死动物,分离胰岛细胞。(4)采用实时定量聚合酶链反应方法比较两组大鼠α细胞 Glc、胰岛素受体底物-1(IRS-1)、胰岛素受体底物-2(IRS-2)、磷酯酰肌醇3激酶(PI3K)的 mRNA 表达的情况。结果(1)HF 组葡萄糖输注率(GIR)明显低于NC 组(5.3 mg·min~(-1)·kg~(-1)±1.2 mg·min~(-1)·kg~(-1)vs 13.6 mg·min~(-1)·kg~(-1)±1.7 mg·min~(-1)·kg~(-1),P<0.01),HF 组血 FFA、Ins 及 Glc 水平显著高于 NC 组(FFA 508(394～622)μmol/L vs 325(240～410)μmol/L,Ins 23.7(14.0～33.4)mIU/L vs 11.5(3.6～19.4)mIU/L;Glc 345(298.6～391.4)pg/ml vs 256(226.4～285.6)pg/ml;P<0.05);(2)HF-B 组比 NC-B 组α细胞 Glc mRNA 的表达高34.2%±2.1%,IRS-2及 PI3K mRNA 分别低28.5%±1.8%、21.3%±1.6%(均 P<0.01),而IRS-1仅降低7.0%±1.2%(P>0.05)。(3)相关分析显示,HF 组血 FFA 水平与 GIR 呈负相关(r=-0.675,P<0.01);且与α细胞 IRS-2 mRNA 表达也呈负相关(r=-0.458,P<0.05)。结论高脂饮食诱导的去β细胞肥胖大鼠胰岛α细胞存在胰岛信号转导分子表达降低,且与血 FFA 水平升高有关。     

Ghrelin改善骨骼肌细胞胰岛素抵抗的机制研究

目的观察酰化ghrelin和非酰化ghrelin分别对胰岛素抵抗（insulinresistance,IR）骨骼肌细胞的胰岛素受体后信号通路关键因子P13Kp85α、Akt／PKB及GLUT4的影响。方法大鼠L6成肌细胞经棕榈酸诱导分化,建立IR模型成功后入选实验,分为酰化ghrelin组（AG组）、非酰化ghrelin组（UAG组）、P13K抑制剂（LY）＋酰化ghrelin组（LY＋AG组）、LY＋非酰化ghrelin组（LY＋UAG组）和对照组（IR—CO组）。各组经处理因素干预24h后,激光共聚焦和流式细胞术检测各组骨骼肌细胞在胰岛素刺激下对荧光葡萄糖的摄取能力,免疫印迹法检测骨骼肌组织的磷酸化／总P13Kp85α、磷酸化／总Akt、细胞膜／总GLUT4的蛋白表达,实时荧光定量PCR法检测骨骼肌组织P13Kp85α、Akt、GLUT4mRNA的表达。结果L6成肌细胞诱导分化及IR模型建立成功;AG组和UAG组的细胞在胰岛素刺激下的葡萄糖摄取分别是IR—CO组的1．25和1．28倍,磷酸形总P13Kp85α相对蛋白表达量分别是IR-CO组的1．78和1．89倍,磷酸化／总Akt、细胞膜／总GLUT4的蛋白表达是IR—CO组的1．84和1．80倍,细胞P13Kp85α、Akt／PKB、GLUT4的mRNA表达均较对照组显著升高,LY＋AG组和LY＋UAG组细胞的上述指标较单独使用酰化ghrelin或非酰化ghrelin作用时显著下降。结论酰化ghrelin和非酰化ghrelin均能改善骨骼肌细胞的IR,增加骨骼肌细胞在胰岛素刺激下的葡萄糖摄取;能够上调骨骼肌细胞的磷酸化P13Kp85α、磷酸化Akt／PKB、细胞膜GLUT4的相对蛋白表达和3者的mRNA表达,PI3K抑制剂LY294002能够抑制酰化和非酰化ghrelin的上述改善作用。