Semaphorin 3A对大鼠慢性心肌梗死周边区交感神经重构的影响

目的:探讨不同浓度Semaphorin 3A(Sema 3A)对大鼠心肌梗死慢性期梗死周边区交感神经重构及心室颤动阈值(室颤阈值)的影响。方法:80只大鼠随机分为两组。心梗组(20只):结扎冠状动脉前降支;Sema 3A组(60只):结扎冠状动脉前降支后于梗死周边区分别注入不同浓度的Sema 3A。8周后测定大鼠梗死周边区室颤阈值,免疫组化染色检测生长相关蛋白43(GAP43)和酪氨酸羟化酶(TH)阳性纤维密度。结果:室颤阈值在Sema 3A注射组中随药物浓度增加而升高,1.0mg/L浓度组相比心梗组有明显提高(P<0.05)。Sema 3A注射组GAP43和TH神经纤维密度与心梗组差异明显(P<0.05);且随药物浓度提高神经纤维密度呈下降趋势,在药物浓度达到1.0mg/L时表现显著(与1.0mg/L组相比P<0.05)。结论:不同浓度的Sema 3A对室颤阈值有不同的提升效应,而对大鼠心肌梗死后交感神经重构产生不同的抑制作用。

Effect of Semaphorin 3A on Sympathetic Nerve Remodeling in Infracted Border Zone of Rat Myocardium

Objective:To explore the impact of Semaphorin 3A (Sema 3A) with different concentrations on sympathetic nerve remodeling and electrical remodeling in myocardial infracted border zone of rats. Methods: Eighty healthy rats were randomly assigned into two groups as myocardicl infarction(MI) group (the left anterior descending coronary artery was ligated) and Sema 3A group (Sema 3A at various concentrations was respectively injected into myocardial infracted border zone of MI rats). Eight weeks after operation, ventricular fibrillation threshold (VFT) was measured at myocardial infracted border zone. Meanwhile, the distribution and densities of growth associated protein 43 (GAP43) and tyrosine hydroxylase (TH) positive nerves were also detected with immunohistochemical technique.Results: VFT of Sema 3A group raised with the increasing concentration of Sema 3A, and 1.0 mg/L Sema 3A group showed significant difference from MI group in VFT (P<0.05). The density of TH and GAP43 in 0.5 mg/L Sema 3A group had significant difference from that of MI group respectively (both P<0.05), and higher concentration Sema 3A groups had less density of TH positive nerves.Conclusion: Sema 3A at certain concentrations may elevate VFT and inhibit sympathetic remodeling.