OBJECTIVE: To observe the effect of electroacupuncture (EA) at \"Neiguan\"(PC6) on cardiac function, cardiac morphology and transient receptor potential channel (TRPC) protein expressions in myocardial tissue of mice with myocardial hypertrophy, so as to explore its mechanisms underlying improvement of myocardial hypertrophy.
METHODS: Forty-five male C57BL/6 mice were randomly divided into control, model and EA groups (15 mice/group). The myocardial hypertrophy model was established by subcutaneous injection of isoproterenol hydrochloride (15 mg·kg-1·d-1) for 14 days. The mice of the control group received subcutaneous injection of same amount of normal saline. The mice of the EA group received EA stimulation (frequency of 2 Hz, intensity of 1 mA) of bilateral PC6 for 20 min each time, once a day for 14 consecutive days. After the intervention, the body weight, tibia length and heart weight were measured. The left ventricular ejection fraction (EF), fractional shortening index (FS), left ventricular end-systolic volume (LVEV), left ventricular end-systolic internal diameter (LVID) and left ventricular posterior wall thickness (LVPW) were measured by using echocardiography for evaluating the cardiac function. The mean number and surface area of myocardial cells was detected by wheat germ agglutinin (WGA) staining, and changes of the cardiac morphology were observed under light microscopy after HE staining. The expression levels of TRPC1, TRPC3, TRPC4 and TRPC6 (TRPC1/3/4/6) in the myocardial tissue were detected by real-time quantitative PCR (qPCR) and Western blot, separately.
RESULTS: Compared with the control group, the heart-body weight ratio(P<0.05) and heart-weight-to-tibia-length ratio (P<0.01), LVEV and LVID levels, the relative surface area, left ventricular area ratio, and the expression levels of cardiac TRPC1/3/4/6 were significantly increased (P<0.01, P<0.05), while the EF, FS, LVPW, number of cardiomyocytes, and the left ventricular posterior wall ratio were obviously decreased (P<0.01, P<0.05) in the model group. In comparison with the model group, the heart/body weight ratio, heart-weight-to-tibia-length ratio, LVEV and LVID levels, relative surface area, left ventricular area ratio, and the expression levels of cardiac TRPC1/3/4/6 were significantly decreased (P<0.01, P<0.05), while the EF, FS, LVPW, number of cardiomyocytes and left ventricular posterior wall ratio were significantly increased (P<0.01, P<0.05) in the EA group. H.E. staining showed disordered arrangement of cardiomyocytes and obvious myocardial interstitial inflammatory cell infiltration in the model group, and evident reduction of degree of cardiac fibrosis and interstitial edema in the EA group.
CONCLUSIONS: EA of PC6 can improve the cardiac function and cardiac morphology in mice with myocardial hypertrophy, which may be related to its functions in down-regulating the expression of transient receptor potential channels.
目的: 观察电针“内关”对心肌肥厚小鼠心功能、心脏形态和心肌组织中瞬时受体电位通道(TRPCs)蛋白表达的影响,探讨电针治疗心肌肥厚的作用机制。方法: C57BL/6小鼠随机分为空白组、模型组和电针组,每组15只。皮下注射盐酸异丙肾上腺素(15 mg·kg-1·d-1)制备心肌肥厚模型。电针组电针双侧“内关”,每次20 min,每日1次,连续14 d。测量小鼠体质量、胫骨长度和心脏质量;超声心动图测量小鼠心室射血分数(EF)、短轴缩短指数(FS)、收缩末期左心室容积(LVEV)、收缩末期左心室内径(LVID)和收缩末期左心室后壁厚度(LVPW)以评价心功能;WGA染色法检测小鼠心肌相对细胞个数和相对细胞平均表面积;HE染色法观察心肌细胞形态变化;qPCR及Western blot法检测心肌组织中TRPC1、TRPC3、TRPC4、TRPC6的mRNA和蛋白表达水平。结果: 与空白组比较,模型组小鼠心体比和心胫比均增加(P<0.05,P<0.01),EF、FS、LVPW降低(P<0.01),LVEV、LVID升高(P<0.01),心肌相对细胞个数减少(P<0.05),心肌相对细胞表面积增加(P<0.01),左心室面积比值升高(P<0.05),左心室后壁比值降低(P<0.05),心肌细胞排列紊乱,心肌间质炎性细胞浸润明显,心肌组织TRPC1、TRPC3、TRPC4、TRPC6 mRNA和蛋白表达明显升高(P<0.01)。与模型组相比,电针组小鼠心体比和心胫比均减小(P<0.01),EF、FS、LVPW升高(P<0.01),LVEV、LVID降低(P<0.01),心肌相对细胞个数增加(P<0.05),相对细胞表面积减小(P<0.05),左心室面积比值降低(P<0.05),左心室后壁比值升高(P<0.05),心肌病理损伤程度减轻,心肌组织TRPC1、TRPC3、TRPC4、TRPC6 mRNA和蛋白表达降低(P<0.01,P<0.05)。结论: 电针“内关”能够改善心肌肥厚小鼠的心脏形态和功能,其机制可能与下调TRPCs有关。.