中文摘要：

目的探讨内脂素（visfatin）基因过表达对高脂诱导的胰岛素抵抗（IR）大鼠胰岛素敏感性及其信号系统的影响。方法构建大鼠内脂素基因重组真核表达质粒pcDNA3.1（＋）-visfatin。20只雄性SD大鼠分为3组。对照组（NC组,n=5）：注射0.3mg空载体pcDNA3.1（＋）,普通饲料组（NT组,n=7）和高脂组（HT,n=8）大鼠注射0.3mg重组质粒pcDNA3.1（＋）-visfatin。在实验前（基础值）、第1次钳夹后即刻、质粒处理后3d和第2次钳夹后即刻,分别自各组大鼠颈静脉取血,分离血浆,采用Westernbloting测定血浆内脂素蛋白表达。在转染前和转染后3d采用两次高胰岛素-正葡萄糖钳夹技术评价大鼠胰岛素敏感性的变化,并测定大鼠空腹血浆胰岛素（FIns）、血糖（BG）、血浆游离脂肪酸（FFA）、甘油三酯（TG）、胆固醇（TC）、高密度脂蛋白胆固醇（HDL-C）、低密度脂蛋白胆固醇（LDL-C）以及葡萄糖输注率（GIR）等指标。采用斑点印迹法检测胰岛素受体底物-1（IRS-1）酪氨酸磷酸化,采用RT-PCR法测定过氧化物酶体增生激活受体γ（PPARγ）mRNA表达水平的变化。结果内脂素质粒注射3d后及第2次钳夹术后,NT和HT组血浆内脂素水平较注射前均升高（P〈0.01）。质粒注射后3d,NT、HT组大鼠TC和HDL-C均较注射前明显降低（P〈0.05）。钳夹术中,NT和HT组大鼠GIR较注射前明显升高（P〈0.01）。NT和HT组大鼠肝脏和肌肉组织中IRS-1酪氨酸磷酸化水平和肝脏中PPARγmRNA水平也较NC组均明显升高（P〈0.05和P〈0.01）。NT组脂肪组织中PPARγmRNA水平较NC组明显增高（P〈0.01）。结论内脂素可能通过上调PPARγmRNA水平和IRS-1酪氨酸磷酸化水平使机体胰岛素敏感性增加。

英文摘要：

Objective To investigate the effects of vislatin gene overexpression on insulin sensitivity and its signaling system in the insulin-resistant rats induced by high fat diet. Methods The control plasmid pcDNA3, 1（＋） and the recombinant overexpression visfatin plasmid PeDNA3. 1-visfatin were transfected into controls （NC group, n= 5）, normal diet rats （NT group, n=7） and high-fat diet rats （HT group, n= 8）, respectively. The plasma samples were collected for baseline values to determine the expression level of visfatin protein in vivo with Western blotting. The insulin sensitivity of rats was detected before and 3 days after plasmid transfection. The fasting insulin （Fins）, blood glucose （BG）, free fatty acids （FFA）, triglyceride （TG）, total cholesterol （TC）, high density lipoprotein cholesterol （HDL-C）, lovedensity lipoprotein cholesterol （LDL-C） and glucose infusion rate （GIR） were also determined. The mRNA expression of peroxisome proliferative activation receptor γ （PPARγ） was examined by RT PCR, and the extent of insulin receptor substrate-1 （IRS-1） tyrosine phosphorylation was detected by dot blot assays. Results The plasma visfatin levels were significantly increased （ P〈0. 01）, and TC and HDL-C were significantly decreased in NT and HT groups （P〈0. 05） 3 days after visfatin plasmid injection and after the second clamping. The Fins levels also decreased in NT group （ P〈0. 05）. The GIR was significantly increased in NT and HT groups, and the extent of IRS-1 tyrosine phosphorylation in response to insulin in liver and muscle tissues were significantly increased compared with NC group （P〈0. 01） 3 days after plasmid injection. The mRNA expression of PPARγ in liver tissue was significantly up-regulated in NT and HT groups compared with NC group （P〈0. 05 and P〈0.01）. In adipose tissues, the PPARγmRNA expression was also significantly up-regulated in NT group compared with NC group （P〈0. 01 ）. Conclusion Visfatin may