解偶联蛋白2基因表达对游离脂肪酸升高所致β细胞功能障碍的影响

目的观察血浆游离脂肪酸（FFA）水平短期升高对β细胞胰岛素分泌功能的影响，探讨线粒体氧化应激在其中的作用及机制。方法将24只8周龄体重160-170g雄性SD大鼠采用随机数字表法分为脂肪乳输注组（FFA组，12只）和生理盐水输注组（NS组，12只）。分别输注48h，检测以下指标：（1）采静脉血检测胰岛素和FFA水平；（2）静脉葡萄糖耐量实验，评价活体胰岛β细胞分泌功能；（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）实时荧光定量聚合酶链反应（PCR）方法检测胰岛细胞胰岛素受体底物1和2（IRS-1、IRS-2）和解偶联蛋白-2（UCP-2）mRNA表达的变化。两组间差异比较采用独立样本t检验。结果FFA组血胰岛素水平较NS组增高（25．2±2．3）比（18．6±1．7）mU／L，t=7．9，P〈0．05]，FFA水平也显著高于Ns组（1．39±0．18）比（0．64±0．10）mmol／L，t=12．8，P〈0．05]。FFA刺激后，FFA组活体和离体的胰岛β细胞分泌功能均较NS组增强活体分别为（137±24）、（80±16）mU／L，t=6．8，P〈0．05；离体分别为（272±4）、（227±4）mU／L，t=28．6，P〈0．05]。与NS组相比，FFA组胰岛细胞IRS-1mRNA表达增加了29．3％4-2．6％（t=2．2，P〈0．05），IRS-2mRNA及UCP-2mRNA表达分别增加了345．1％±4．7％、228．4％±4．2％（t=3．4、3．0，均P〈0．05）。结论血浆FFA水平短期升高对β细胞胰岛素分泌有刺激作用，但同时激活线粒体氧化应激，使UCP-2表达相应增加。

Influence of uncoupling protein 2 gene expression to the dysfunction of beta cells caused by increased free fatty acid

Objective To study the changes and mechanisms of the function of islet β cells after short term lipid infusion and its relation to mitochondrial oxidative stress. Methods Twenty four SD rats （weight 160-170 g,8-week old） were randomly divided into 2 groups with random number table： free fat acid（ FFA ） group and normal saline （NS） group, which were infused with fat emulsion or saline respectively. Catheters were implanted under pentobarbital anesthesia in the right atrium via the jugular vein and the left carotid artery. A technique for a 48 h infusion in unrestrained rats was used for fat emulsion and heparin or saline infusion. The infusion period started on day 2 after surgery. After 48 h infusion, fasting serum insulin（INS） , venous free fat acid were determined. The intravenous glucose tolerance test and islet cell perifusion were conducted to evaluate the function of islet β cell. The rats in the two groups were sacrificed, and the pancreatic islets were isolated and collected. The expression of insulin receptor substrate-1 （ IRS-1 ） ,insulin receptor substrate-2 （ IRS-2 ） , uncoupling protein-2 （ UCP2 ） gene in islets were detected by real-time polymerase chain reaction （PCR）. Student＇s t test was used for data analysis. Results The serum FFA and insulin concentration of blood in FFA group were higher than those in NS group （ insulin （ 25.2 ± 2.3） vs （18.6 ± 1.7）mU/L,t =7.9,P 〈0.05,FFA （1.39 ±0. 18） vs（0.64 ±0. 10） mmoL/L,t = 12. 8, P 〈0. 05）. The glucose stimulated insulin secretion increased in the FFA group than in NS group （（ 137 ± 24） vs （80±16） mU/Linvivo,t=6.8,P〈0.05;（272±4） vs （227±4） mU/Linvitro,t=28.6,P〈 0.05 ）. The gene expression of IRS-1 in islets was significantly increased by 29.3% ± 2.6% （ t = 2. 2, P 〈 0. 05） ,and the mRNA expression of IRS-2,UCP-2 increased by 345.1% ±4. 7% and 228.4% ±4. 2% inFFA group than those in NS group （ t = 3.4,3.0, all P 〈 0.05 ）. Conclusion Lipid infusion in short-term increases the secretion of insulin but it can also increase the gene expression of UCP-2, which can damage islet βcells.