荞麦花叶总黄酮对2型糖尿病大鼠心肌纤维化的保护作用及其机制

目的：探讨荞麦花叶总黄酮（TFBFL）对2型糖尿病大鼠心肌损伤的保护作用，阐明其作用机制。方法：采用腹腔注射链脲佐菌素（STZ）加高脂饲料的方法建立2型糖尿病大鼠模型。造模成功的12只大鼠随机分为模型（DM）组（n=6）和TFBFL治疗组（n=6），同时设正常对照组（n=8），正常对照组和DM组大鼠给予10 mL·kg^-1·d^-1纯净水灌胃；TFBFL治疗组大鼠给予200 mL·kg^-1·d^-1 TFBFL灌胃。各组大鼠每天给药1次，连续8周。检测各组大鼠体质量（BW）、心脏质量指数（HWI）、血糖水平（FBG）及心功能指标心率（HR）、左室收缩压（LVSP）、左心室舒张期末压（LVEDP）和左室内压最大上升和下降速率（±dp/dt_max）]。电镜下观察各组大鼠心肌细胞超微结构，Masson染色观察各组大鼠心肌组织中的胶原水平，Western blotting法检测各组大鼠心肌组织中TGF-β1蛋白表达水平。结果：与正常对照组比较，DM组大鼠HWI、FBG和LVEDP明显升高（P < 0.05或P < 0.01），而BW、LVSP、HR和±dp/dt_max则明显降低（P < 0.05或P < 0.01）；与DM组比较，TFBFL组大鼠FBG和LVEDP水平明显降低（P < 0.01），而LVSP、HR和±dp/dt_max明显升高（P < 0.05或P < 0.01）。TFBFL组大鼠BW和HWI与DM组比较差异无统计学意义（P > 0.05）。电镜下观察和Masson染色检测，与DM组比较，TFBFL组大鼠心肌组织形态明显改善，胶原水平降低。Western blotting检测，与正常对照组比较，DM组大鼠心肌组织中TGF-β1蛋白表达水平明显升高（P < 0.05）；与DM组比较，TFBFL组大鼠心肌组织中TGF-β1蛋白表达水平明显降低（P < 0.05）。结论：TFBFL对2型糖尿病大鼠心肌纤维化具有保护作用，其机制与抑制心肌组织中TGF-β1表达有关联。

Protective effect of total flavones of buckwheat flowers and leaves on myocardial fibrosis of type 2 diabetic rats and its mechanism

Objective: To study the protective effect of the total flavones of buckwheat flowers and leaves (TFBFL)on the myocardial injury of the type 2 diabetic rats,and to clarify its mechanism.Methods:The diabetic rat models were established by intraperitoneally injecting streptozotocin (STZ)and taking high-fat diet.The model rats were divided into diabetic model (DM)group and TFBFL treatment (TFBFL)group,while normal control group was set up, 10 rats per group.The rats in TFBFL group were administered with 200 mL· kg-1 · d-1 TFBFL,while the rats in other two groups were given with normal water (10 mL·kg-1 ·d-1 )instead.The rats in various groups was administered once a day for 8 weeks.The body weight (BW),heart weight index (HWI), level of fasting blood glucose (FBG)and cardiac function indexes (HR,LVSP,LVEDP and ± dp/dtmax )of the rats in various groups were measured.The myocardial tissue morphology of the rats in various groups was evaluated by electron microscope and the collagen levels in myocardium tissue of the rats in various groups were observed by Masson staining.The expression levels of TGF-β1 protein in myocardium tissue of the rats in various groups were detected by Western blotting method.Results:Compared with normal control group,the HWI,FBG and LVEDP levels of the rats in DM group were increased (P <0.05 or P <0.01),and the BW, HR,LVSP and ±dp/dtmax level in DM group were decreased (P <0.05 or P <0.01).Compared with DM group,the FBG and LVEDP level in TFBFL group were decreased (P < 0.01 ),and the HR,LVSP and ± dp/dtmax level in TFBFL group were increased (P < 0.05 or P < 0.01 ); but the BW and HWI level in TFBFL group had no significant difference compared with DM group (P >0.05).The Masson staining results showed the morphology of myocardium tissue of the rats in TFBFL group was improved and the collagen level was decreased. The Western blotting results suggested that the TGF-β1 protein expression level in myocardium tissue of the rats in DM group was significantly increased compared with normal control group (P < 0.05),and the TGF-β1 protein expression level of the rats in TFBFL group was decreased compared with DM group (P <0.05).Conclusion:TFBFL exerts a certain protective effect on the myocardial fibrosis of diabetic rats through inhibiting the TGF-β1 expression in myocardium tissue.