糖尿病大鼠缺血/再灌注心肌细胞凋亡及相关基因表达的研究

目的观察链脲佐菌素(STZ)诱导的糖尿病大鼠缺血/再灌注(I/R)模型心肌细胞凋亡及相关基因的表达。方法采用STZ(45 mg/kg)诱导大鼠糖尿病4周后制备心肌缺血30 min再灌注120 min模型,用2,3,5-氯化三苯基四氮唑染色法(TTC)测定心肌梗死面积,用TUNEI法检测细胞凋亡,用免疫组化方法检测凋亡相关基因的表达,透射电镜观察心肌组织超微结构的凋亡改变。结果与非糖尿病组相比,糖尿病组大鼠由I/R损伤引起的心肌梗死面积并没有增加,但是细胞凋亡指数增加(17%±3%比26%±3%,P<0.001)、Bcl-2表达降低(11.0%±3.8%比3.8%±2.5%,P<0.001)、Bax表达升高(26%±3%比36%±7%,P<0.001)、超微结构观察心肌凋亡损伤更为严重。结论糖尿病大鼠I/R心肌细胞凋亡增加,这可能与凋亡相关基因Bcl-2表达降低、Bax表达升高有关。

Study on ischemia-reperfusion induced apoptosis and relative apoptotic genes expression in cardiomyocyte of diabetic rats

Objective To observe the ischemia-reperfusion induced apoptosis and relative apoptotic genes expressions in cardiomyocyte of streptozotocin （STZ）-induced diabetic rats. Methods STZ-induced diabetic rats were subjected to 30 rain of myocardial ischemia following 120 min of reperfusion injury 4 weeks after the use of STZ 45 mg,/kg. Myocardial infarct size was measured using 2,3,5- Triphenyhetrazolium chloride （ TTC ）. Cardiomyocyte apoptosis was assessed using terminal deoxyribonueleotidyl transferase-mediated dUTP nick-end labeling （TUNEL） assay. The expressions of antiapoptotic gene （ Bcl-2 ） and proapoptotic gene （ Bax ） was determined by immunohistochemistry. The apoptotic change of myocardial ultrastructure was examined by electron microscope. Results Compared with non-diabetic rats, the myocardial infarct size of diabetic rats induced by ischemia-reperfusion didn＇t enlarge. However, myocardial AI was increased （ 17% ± 3% vs. 26% ±3% , P 〈 0. 001 ） , the expression of Bcl-2 was decreased （ 11.0% ± 3.8% vs. 3.8% ±2.5%,P〈0.001）, the expression of Bax was increased （26% ±3% vs. 36% ±7%,P〈0.001）, and the myocardial uhrastructure demonstrated that cardiomyocyte apoptosis was more serious. Conclusions Ischemia-reperfusion induced apoptosis of cardiomyocyte is increased in STZ-induced diabetic rats, which probably have related with decreasing the expression of Bcl-2 and ratio of Bcl-2/Bax.