血小板源生长因子在糖尿病大鼠心肌的表达及意义

目的探讨血小板源生长因子-B（PDGF-B）在糖尿病心肌病发病机制中的作用。方法8周龄雄性sD大鼠60只，随机分为对照组30只、糖尿病组30只。链脲佐菌素（STZ）一次性腹腔注射建立糖尿病模型，每2周测量血糖、体重。在病程4周、8周、12周分别从两组大鼠中随机选择6只，称量并计算心体比（H／B）和左室重量指数（LVMI）。电镜观察比较12周糖尿病组与对照组大鼠心肌超微结构，光镜观察比较两组冠脉病变。RT～PCR比较不同病程各组大鼠心肌PDGF—B、纤维连接蛋白（FN）、Ⅲ型胶原（Colm）的mRNA表达情况。结果STZ诱导糖尿病SD大鼠在病程12周糖尿病心肌病已形成。在病程4周、8周、12周，糖尿病组H／B、LVMI逐渐增加，心肌PDGF—B mRNA表达显著上调（P〈0．01），随着病程延长，呈逐渐增高趋势，与FN、Col Ⅲ表达进行性增高相平行。PDGF—B与FN、Col ⅢmRNA表达呈明显正相关（r=0．766，0．794，均P〈0．01）。结论糖尿病大鼠心肌PDGF—B表达上调与细胞外基质（ECM）的积聚密切相关，在糖尿病心肌病形成过程中起重要作用。

Expression of platelet-derived growth factor-B in the myocardium of diabetic rats

Objective To investigate the expression of platelet-derived growth factor-B （PDGF-B） in the myocardium of diabetic rats and to evaluate the role of PDGF-B in the pathogenesis of diabetic cardiomyopathy. Methods Sixty SD rats were randomized into two groups, the normal control group and diabetic group.Diabetes was induced by streptozotocin （STZ） intraperitoneal injection. Six rats were selected at random from the two groups respectively at 4,8,12 weeks of diabetic duration.The weights of body, whole heart and left ventricle were measured to calculate the ratio of heart weight to body weight （H/B） and the left ventricle mass index （LVMI）. The myocardial uhrastructure of the two groups at 12 weeks duration was observed by electron microscope, the coronary artery oritices were also observed by light microscope. The mRNA expression of PDGF-B,fibronectin （FN） ,collagen type Ⅲ （Col Ⅲ）were compared between the two groups of various duration by RT-PCR. Results In 12 weeks,STZ-induced diabetic SD rats showed conspicuous myocardial lesions. No abnormality was found along the coronary artery oritices. These results indicated the formation of diabetic cardiomyopathy. H/B and LVMI were raised in the diabetic group,which were aggravated with the developemet of diabetes. Notable upregulation of PDGF-B mRNA coincidented with an apparent increase of FN, Col Ⅲ expression in diabetic myocardium （P〈0.01 respectively）. These alterations were enhanced gradually along with longer diabetic duration. PDGF-B had a signif- icant positive correlation with FN and Col Ⅲ （r=0.766,0.794,P〈0.01 respectively）. Conclusion Upregnlation of PDGF-B is strongly correlated with the concomitant accumulation of extracellular matrix （ECM） component in the myocardium of diabetic rats. PDGF-B may marked contribute to the formation of diabetic cardiomyopathy.