糖尿病大鼠心肌TGF-β1表达及细胞凋亡的实验研究

目的:研究糖尿病大鼠心肌转化生长因子β1(TGF-β₁)表达水平和细胞凋亡的变化，探讨糖尿病性心肌病的病理生理机制。方法：链脲菌素法复制不同病程的糖尿病模型。免疫组化方法测定TGF-β₁的表达。DNA断端末端标记法测定心肌细胞凋亡指数。结果：糖尿病大鼠心肌细胞TGF-β₁表达明显高于正常对照组（P<0.01）。TUNEL法测定心肌细胞的凋亡阳性细胞数量在糖尿病早期明显高于正常，晚期有所减少。结论：TGF-β₁在糖尿病的心肌中表达增加，且随病程发展而上升，可能是糖尿病心肌纤维化的重要促发因子。糖尿病心肌中细胞凋亡现象随病程延长而逐渐减弱，机制有待探讨。

Expression of TGF-β1 and apoptosis in myocardium of diabetic rats

AIM: To study the pathophysiological mechanism of cardiomyopathy, the expression of TGF-β₁ and apoptosis in myocardium of diabetic rats were investigated. METHODS:The diabetes models were established by single intravenous injection of streptozotocin (50 mg/kg) in rats. By the method of immunochemistry, the expression of TGF-β₁ in the cardiomyocytes was detected as the index to evaluate the degree of fibrosis. The method of TUNEL was used to measure the cardiomyocyte apoptosis as the index to explore its importance in process of diabetic cardiomyopathy. RESULTS:① The weight of diabetic rats was apparently lower than that in the rats before the diabetic model was built (P<0.01), and the increase in weight in diabetic rats within three month was less than that in normal group. ② Compared with control group, the concentration of blood glucose was continually elevated during the experiment. ③ The expression of TGF-β₁ in the diabetic cardiac muscle was much more than that in normal group (P<0.01). ④ The apoptosis of myocardium measured by the method of TUNEL was apparent in the diabetic groups than that in normal one (P<0.01). However, no significance was detected in the different courses of diabetic groups. CONCLUSIONS:The apoptosis might play an important role in leading the diabetic cardiomyopathy to heart failure. The expression of TGF-β₁ in the myocardium of diabetic rats was more than that in normal and had an increasing trend in the procession of diabetic cardiomyopathy. TGF-β₁ might be a significant factor in diabetic myocardium fibrosis. Apoptosis might play an important role in the initial stage of diabetes, which promotes the diabetic cardiomyopathy to heart failure.