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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。
This study aimed to observe the changes of myocardial activity of thioredoxin (Trx) system in type 2 diabetic rats with myocardial injury and to explore its mechanism. Adult Sprague Dawley rats were randomly divided into 2 groups: diabetic group were given high-sugar, high-fat diet, and intraperitoneal injection of streptozocin (STZ) caused type 2 diabetic rats; control group fed normal diet, intraperitoneal injection of lemon Acid buffer. The levels of serum insulin, creatine kinase MB (CK-MB) and cardiac troponin I (cTnI) were measured at different time points after STZ injection. The levels of myocardial Trx Trx reductase (TR) activity and caspase-3 activity were determined by real time PCR and Western blot. The mRNA and protein expressions of Trx1, Trx2, TR1, TR2 and TXNIP in myocardium were determined by real time PCR and Western blot . The results showed that in the first week after STZ injection, type 2 diabetic rat model was successfully established; myocardial injury was induced in the second week after injection of STZ, and caspase-3 activity was increased in the fourth week. The activity of Trx and TR in cardiac muscle of diabetic rats decreased significantly at the second week after STZ injection and decreased progressively with the course of disease. The mRNA levels of Trx1, Trx2, TR1 and TR2 in diabetic rats were all increased after 4 weeks Significantly decreased at week 12 and significantly increased at week 12; Western blot results showed that the expression of Trx, TR and TXNIP in myocardium of diabetic rats increased significantly at the 12th week after injection of STZ. The above results show that Trx and TR activity is inhibited in myocardial injury of type 2 diabetic rats, while the mRNA expression of Trx and TR is repressed after compensatory increase, TXNIP expression is significantly increased, Trx system protein expression were significantly increased, suggesting The main reason for the decreased activity of Trx system may be the increase of inhibitory protein expression and chemical modification.