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  

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

作　　者：王冰[1] 李宏亮[1] 杨文英[1] 萧建中[1] 杜瑞琴[1] 白秀平[1] 楼大钧[1] 潘琳[2] 

机构地区：[1]卫生部中日友好医院内分泌科,北京100029 [2]卫生部中日友好医院临床医学研究所内科实验室,北京100029

出　　处：《中华医学杂志》2008年第9期630-634,共5页National Medical Journal of China

基　　金：国家自然科学基金资助项目（30640081）

摘　　要：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-1mRNA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。Objective To study the effects of high fat diet on the functions of islet β 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 β 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. O1 ）. （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 · min^-1 · kg^-1 , significantly lower r than that of the NC group [ （ 13.6 ± 1.7） mg · min^-1 · 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.

关 键 词：氧化应激 胰岛Β细胞 解偶联蛋白2 

分 类 号：R686[医药卫生—骨科学]