电针对心肌缺血小鼠心肌组织交感神经相关物质的影响

Effects of electroacupuncture on sympathetic nerve-related substance in myocardial tissue in mice with myocardial ischemia

目的:观察电针对心肌缺血模型小鼠心肌组织交感神经相关物质的影响,探讨其作用机制。方法:将30只成年雄性C57BL/6小鼠随机分为假手术组、模型组和电针组,每组10只。模型组和电针组采用冠状动脉左前降支结扎法建立心肌缺血模型。假手术组不进行冠状动脉左前降支结扎,其余步骤同模型组。电针组电针"内关"穴,疏密波,频率2 Hz/100 Hz,电流强度2 mA,每天1次,每次20 min,共治疗5 d;假手术组和模型组仅抓取、固定,不予电针治疗。记录Ⅱ导联心电图并计算△ST值进行模型评价;采用TTC染色评价小鼠心肌梗死面积;免疫组化评价小鼠心肌组织阳性神经纤维密度;Western blot检测小鼠心肌组织神经调节蛋白-1(NRG-1)、酪氨酸羟化酶(TH)、生长相关蛋白-43(GAP-43)的蛋白表达水平。结果:Ⅱ导联心电图显示,与假手术组相比,模型组和电针组S-T段显著抬高(均P<0.01),提示缺血模型成功建立;TTC染色结果显示,与假手术组相比,模型组心肌梗死面积显著增加(P<0.01),与模型组相比,电针组心肌梗死面积显著减小(P<0.01);免疫组化结果显示,与假手术组相比,模型组小鼠心肌TH阳性神经纤维密度显著增加(P<0.01),与模型组相比,电针组心肌组织TH阳性神经纤维密度显著减小(P<0.05);Western blot结果显示,与假手术组相比,模型组TH、NRG-1、GAP-43的蛋白表达水平显著升高(均P<0.01),与模型组相比,电针组心肌组织中TH、GAP-43蛋白表达显著降低(均P<0.01),NRG-1蛋白表达显著升高(P<0.05)。结论:电针可能通过增加心肌缺血小鼠心肌组织中NRG-1蛋白表达水平,降低TH、GAP-43蛋白表达水平,抑制梗死后交感神经过度兴奋,实现心肌保护效应。

Objective To observe the effects of electroacupuncture(EA)on sympathetic nerve-related substance in myocardial tissue in mice with myocardial ischemia(MI),and to explore its possible mechanism.Methods Thirty adult male C57 BL/6 mice were randomly divided into a sham operation group,a model group and an EA group,10 mice in each one.The model of MI was established in the model group and EA group by ligating the left anterior descending branch of coronary artery.The mice in the sham operation group were not treated with ligating at left anterior descending branch of coronary artery,but the remaining procedure was similar with the model group.The mice in the EA group were treated with EA at"Neiguan"(PC 6)with 2 Hz/100 Hz of frequency and 2 mA of intensity,20 min per treatment,once a day for totally 5 days.No EA was given for model group and sham operation group.The electrocardiogram was recorded and△ST value was calculated to evaluate the model.TTC staining was applied to evaluate the infarct size.Immunohistochemical(IHC)method was applied to evaluate the positive nerve fiber density in myocardial tissue.Western blot method was applied to test the protein expression levels of neuregulin-1(NRG-1),tyrosine hydroxylase(TH),growth associated protein-43(GAP-43).Results The electrocardiogram(lead II)results indicated compared with the sham operation group,the S-T segments in the model group and EA group were increased obviously(both P<0.01),indicating the MI model was established successfully.The TTC staining results indicated compared with sham operation group,the infarction size was significantly increased in the model group(P<0.01);compared with the model group,the infarction size in the EA group was significantly reduced(P<0.01).The IHC results indicated compared with the sham operation group,the positive nerve fiber density in myocardial was increased in the model group(P<0.01);compared with the model group,the positive nerve fiber density in myocardial was reduced in the EA group(P<0.05).The Western blot results indicated compared with the sham operation group,the expression levels of TH,NRG-1 and GAP-43 were significantly increased in the model group(P<0.01);compared with the model group,the expression level of TH and GAP-43 were significantly reduced(P<0.01)and that of NRG-1 was increased in the EA group(P<0.05).Conclusion EA could increase the expression of NRG-1 and reduce the expression of TH and GAP-43 in myocardial tissues in MI mice,which could suppress sympathetic nerve hyperexcitability after infarction to achieve myocardial protection effect.