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[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

Received: 2010-03-16　　Accepted: 2010-05-17

Corresponding author: 焦向英　　E-mail: jiaoxy@gmail.com

Citing This Article：

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).