糖尿病大鼠心肌纤维化的病理改变和超声背向散射积分参数评价

目的：观察糖尿病大鼠不同病程心肌纤维化的病理表现及TGF-β1，CTGF在糖尿病心肌病变中的水平，探讨IBS与心肌纤维化程度及心脏功能的关系。方法：腹腔注射链尿佐菌素（65mg／奴）建立sD大鼠糖尿病模型，于第4、12、2，4周测定测定常规心功能参数左室射血分数（LVEF）、左室后壁校正的IBS值（IBS％）、IBS周期性变异幅度（CWB）。Masson胶原染色观察纤维容积分数（CVF）及血管周围胶原面积（PVCA），心肌胶原蛋白Ⅰ（collagenⅠ）、转化生长因子β1（TGF-β1）和结缔组织生长因子（CTGF）免疫组织化学染色。心肌光镜与透射电镜观察，并与同龄正常大鼠进行比较。结果：①与对照组相比：糖尿病组的IBS％明显增高（P〈0．05），CVIB第4、12周时尚无明显变化（P〉0．05），第24周时明显减低（P〈0．05），EF值各组间无明显变化（P〉0．05）；糖尿病组心肌纤维化指标CVF、PVCA、CollagenⅠ及TGF-β1和CTGF的表达均明显增高（P〈0．05）；②IBS％与CVF、PVCA、CollagenⅠ、TGF-β1、CTGF表达呈正相关（P〈0．05）；TGF-β1和CTGF表达分别与CVF、PVCA、CollagenⅠ呈正相关（P〈0．05），TGF-β1和CTGF表达呈正相关。电镜发现糖尿病组心肌细胞肌丝稀疏，线粒体肿胀，间质胶原增生。结论：糖尿病大鼠存在明显的心肌纤维化，糖尿病心肌纤维化与TCF-β1、CTGF的表达增强有关。应用IBS技术可以检测到与纤维化指标（CVF、PVCA、CollagenⅠ、TGF-β1、CTGF）有关的IBS％增高。

The pathologic changes of myocardial fibrosis in diabetes mellitus rats and evaluation by integrated backscatter ultrasound parameters

Objective：To observe pathologic changes of myocardial fibrosis at different stages of diabetes mellitus rats and the level of TGF-β1, CTGF in the diabetic cardiomyopathy, to explore dynamic changes of integrated backscatter ultrasonic parameters in diabetic rats and the degree of myocardial fibrosis and cardiac function. Methods：The diabetes mellitus in healthy male Sprague-Dawley rats was induced by a single injection of streptozotocin （STZ, Sigma） into intraperitoneal at a dose of 65 mg/kg body weight. Left ventricular ejection fraction （LVEF）,myocardial calibrated IBS（IBS%）, the cyclic variation of IBS（CVIB） by IBS, were determined in rats of 4, 12 and 24 weeks after DM was induced. Masson trichrome staining were used in the study of total collagen area. The type 1- collagen, the transforming factor beta 1 （TGF-beta 1 ）, connective tissue growth factor（CTGF） protein expression was evaluated in heart, while the agematched normal rats served as control group. Myocardiopathological changes were observed with light microscope and transmission electron microscope. Results ： ① The IBS% of left ventricular posterior wall was significantly higher in diabetic rats than those in the control group （ P 〈0.05）, but the CVIB of 24-week diabetic rats was lower （ P 〈0.05）. The LVEF had no great alteration in six groups （ P 〉 0.05）. Compared with the collagen volume fraction（CVF）, perivascular collagen area （PVCA）, and the expression of the type Ⅰ collagen, TGF-β1, CTGF in heart were increased in diabetic rats （ P 〈 0.05） ; ② The correlation between IBS% and tIPC, CVF, PVCA, collagen 1- , TGF-β1, CTGF were significant（ P 〈 0.05）. The expression of TGF-β1 and CleF with the CVF, PVCA, collagen Ⅰ- were positive correlation respectively （ P 〈 0.05）. Also the correlation between TGF-β1 and CTGF were significant （ P 〈 0.05）. Myofilament rarefaction, mitrochondrial swelling, interstitial collagen hyperplasia in diabetic rats were observed by electron microscope. Conclusion：There is an obvious cardiac fibrosis in diabetic rats. Myocardial fibrosis in diabetic rats may be relaed with overexpression of TGF-β1 and CTGF. The IBS% of left ventricular posterior wall, which has been demonstrated to reflect the degree of myocardial fibrosis （CVF, collagen Ⅰ, TGF-β1, CTGF）.