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2 型糖尿病大鼠心肌损伤时心肌组织中硫氧还蛋白系统的变化

赵晓琴, 赵俊杰, 李晓宇, 张燕, 焦向英

山西医科大学生理教研室，山西医科大学细胞生理学省部共建教育部重点实验室，太原 030001； 山西体育职业学院， 太原 030006

摘要

本研究旨在观察2 型糖尿病大鼠心肌损伤时硫氧还蛋白(thioredoxin, Trx)系统在心肌组织中的活性变化，并探讨其机制。成年Sprague Dawley 大鼠随机分为2 组：糖尿病组给予高糖、高脂饮食，并且腹腔注射链唑霉素(streptozocin, STZ)造成大鼠2 型糖尿病模型；对照组普通饲料喂养，腹腔注射柠檬酸缓冲液。在注射STZ 后不同时间点，测定大鼠血糖浓度和血清胰岛素、肌酸激酶同工酶(creatine kinase MB, CK-MB)、心肌肌钙蛋白I (cardiac troponin I, cTnI)浓度，测定心肌Trx 活性、Trx 还原酶(thioredoxin reductase, TR)活性和caspase-3 活性，用real time PCR 和Western blot 测定心肌Trx1、Trx2、TR1、TR2 和Trx 相关蛋白(thioredoxin interacting protein, TXNIP)的mRNA 和蛋白表达。结果显示，注射STZ 后第1 周，2 型糖尿病大鼠模型建立成功；注射STZ 后第2 周即可诱发心肌损伤，第4 周上调caspase-3 活性。糖尿病组大鼠心肌Trx和TR 活性在注射STZ 后第2 周显著降低，并随病程呈进行性下降；糖尿病组大鼠心肌Trx1、Trx2、TR1、TR2 的mRNA水平均在注射STZ 后第4 周显著下降，而在第12 周时则明显升高；Western blot 结果显示糖尿病组大鼠心肌Trx、TR、TXNIP 蛋白表达在注射STZ 后第12 周时均显著升高。以上结果表明，2 型糖尿病大鼠心肌损伤时Trx 和TR 活性受抑，而Trx、TR 的mRNA 表达受到抑制后，代偿性增多，TXNIP 的表达明显上调，Trx 系统蛋白表达均明显上调，提示Trx 系统活性下降的主要原因可能是抑制性蛋白表达升高和化学修饰。

关键词： 2 型糖尿病; 心肌; 损伤; 硫氧还蛋白

分类号：R587.1

[The change of thioredoxin system in myocardial tissue of type 2 diabetic rats undergoing myocardial injury.] [Ariticle in Chinese]

ZHAO Xiao-Qin, ZHAO Jun-Jie, LI Xiao-Yu, ZHANG Yan, JIAO Xiang-Ying

Department of Physiology, Key Laboratory of Cellular Physiology, Shanxi Medical University, Taiyuan 030001, China； Shanxi Sport Vocational College, Taiyuan 030006, China

Abstract

The aim of the present study is to investigate the change of thioredoxin (Trx) system in myocardial tissue of type 2 diabeticrats after myocardial injury and the underlying mechanism. Adult Sprague Dawley rats were randomly divided into two groups: normalcontrol (NC) group and diabetes (DM) group. Rats in DM group were subjected to high-sugar, high-fat diet and streptozotocin (STZ)injection. Rats in NC group were only given normal diet and equal amount of citric acid buffer injection. At week 1, 2, 4, 12, 21 after STZinjection, plasma glucose concentration and the concentrations of insulin, creatine kinase MB (CK-MB), cardiac troponin I (cTnI) inserum were measured. Myocardial Trx and thioredoxin reductase (TR) activities, as well as caspase-3 activity, were determined byrespective assay methods. Protein and mRNA levels of Trx, TR, Trx interacting protein (TXNIP) were determined by Western blot andreal time PCR, respectively. The results showed that type 2 diabetic rat model was successfully established at week 1 after STZinjection, and myocardial injury was induced from week 2. Moreover, caspase-3 activity was significantly increased at week 4, 12 indiabetic rats. The activities of myocardial Trx and TR in diabetic rats was decreased from week 2, and continually aggravated as thedisease developed. Compared with those in NC group, the mRNA levels of Trx1, Trx2, TR1, TR2 in DM group decreased at week 4,and then increased in week 12. In DM group, the protein levels of Trx1, Trx2, TR1 and TR2 increased significantly at week 12. ThemRNA expressions of myocardial TXNIP in diabetic rats were significantly increased at week 4, 12, 24 and protein expression wasincreased at week 12. These results suggest diabetes can decrease myocardial Trx, TR activity, inducing myocardial cell apoptosis andheart injury. The inhibitory effect of diabetes is mainly associated with TXNIP up-regulation and Trx nitration.

Key words: diabetes mellitus, type 2; myocardial; injury; thioredoxin

收稿日期：2010-03-16　　录用日期：2010-05-17

通讯作者：焦向英　　E-mail: jiaoxy@gmail.com

引用本文：

赵晓琴, 赵俊杰, 李晓宇, 张燕, 焦向英. 2 型糖尿病大鼠心肌损伤时心肌组织中硫氧还蛋白系统的变化[J]. 生理学报 2010; 62 (3): 261-268.

ZHAO Xiao-Qin, ZHAO Jun-Jie, LI Xiao-Yu, ZHANG Yan, JIAO Xiang-Ying. [The change of thioredoxin system in myocardial tissue of type 2 diabetic rats undergoing myocardial injury.] [Ariticle in Chinese] . Acta Physiol Sin 2010; 62 (3): 261-268 (in Chinese with English abstract).