糖原合成激酶3β在二氮嗪后处理糖尿病大鼠心肌缺血／再灌注损伤中的作用

The role of glycogen synthase kinase-3β in myocardial ischemia/reperfusion injury in diazoxide postconditioned diabetic rats

目的观察糖原合成激酶3B（glycogensynthasekinase-3β，GSK-3β）在二氮嗪（diazoxide，DZ）后处理糖尿病大鼠心肌缺血，再灌注损伤（ischemia／reperfusioninjury，I／RI）中的作用及机制。方法单次腹腔注射链脲佐菌素（streptozotocin，STZ）制备糖尿病大鼠模型，取造模成功的大鼠48只，复制在体心肌缺血／再灌注（ischemia／reperfusion，I，R）模型，按随机数字表法分为4组（每组12只）：假手术组（Sham组）、I／R组（I组）、DZ组（D组）、SB216763＋DZ组（S组）。连续监测血流动力学指标，比色法测血浆乳酸脱氢酶（1actatedehydrogenase，LDH）活性，2，3，5-氯化三苯基四氮唑（triphenyl tetrazolium chloride，TTC）染色分析心肌梗死面积，Westernblot测磷酸化GSK-3β（phosphorylatedGSK-3β，pGSK-3β）的表达。结果与I组及D组比较，S组心功能明显改善（／9〈0．05），血浆LDH[S组、I组、D组为（5335±502）、（7943±831）、（7176±521）U／L，P〈0．05]活性及心肌梗死面积[S组、I组、D组为（21．0±1．6）％、（30．8±3．8）％、（31．3±2．9）％，P〈0．05]均显著降低，pGSK-3β表达增加（P〈0．05）；I组与D组比较上述指标差异无统计学意义（P〉0．05）。结论DZ后处理对糖尿病大鼠心肌I／RI无保护作用，GSK-3β抑制剂干预后DZ后处理对糖尿病大鼠心肌I／RI的保护作用恢复。

Objective To observe the role and mechanism of glycogen synthase kinase-3β （GSK-3β） in myocardial ischemia/reperfusion injury （URI） by diazoxide （DZ） postconditioning in diabetic rats. Methods The diabetic rat model was established by single intraperitoneal injection of streptozotocin. After the model was duplicated successfully, in vivo myocardial ischemia/reperfusion （I/R） model was developed in 48 rats. Then the rats were randomly divided into 4 groups （n=12）： sham operation group （group Sham）, I/R group （group I ）, DZ group （group D）, SB216763 and DZ group （group S）. Hemodynamic parameters were monitored continuously. The plasma cardiac enzymes lactate dehydrogenase （LDH） and myocardial infarct size were measured by eolorimetric measurement and 2,3,5-triphenyhetrazolium chloride （T＇FC） staining, respectively. The protein expression of phosphorylated GSK-3β （pGSK-3β） in the heart was detected by Western blot. Results Compared with group I and group D, cardiac function was improved in group S（P〈0.05）. The levels of plasma LDH [group S vs group I vs group D： （5 335±502） U/L vs （7 943±831 ） U/L and （7 176±521 ） U/L, P〈0.05 ] and myocardial infarct size [group S vs group I vs group D： （21.0±1.6）% vs （ 30.8±3.8 ）% and （31.3±2.9）%, P〈0.05 ] significantly decreased. The expression of pGSK-3β was increased （P〈0.05）. There was no significant difference between group I and D （P〉0.05）. Conclusions DZ posteonditioning can＇t protect diabetic rat heart against I/ RI, but can exert the protective function after interfered with GSK-3β inhibitor.