靶向损毁心交感神经元预防心肌梗死后室性心律失常和心脏性猝死的实验研究

Sympathetic activation is an important factor for induction of ventricular arrhythmias and sudden cardiac death after myocardial infarction. Targeted ablation of cardiac sympathetic neurons is a preganglionic denervation,which suggests that there would be no reinnervation and postdenervation supersensitivity.Importantly, it doesn't affect afferent pathways. Previous studies demonstrated that targeted ablation of cardiac sympathetic neurons can inhibit cardiac sympathetic activity and reduce sympatheic innervation density.Our preliminary experiment found that targeted ablation of cardiac sympathetic neurons significantly inhibited stellate ganglion activity and reduced sympathetic nerve remodeling after myocardial infarction . In this project, we propose for the first time that targeted ablation of cardiac sympathetic neurons may prevent ventricular arrhythmias and sudden cardiac death after myocardial infarction. We will creat dog models of myocardial infarction and sudden cardiac death after myocardial infarction, and determine the effects of targeted ablation of cardiac sympathetic neurons on ventricular and atrial electrophysiological properties as well as the effects on sinoatrial node and atrioventricular node functions. Furthermore, we will investigate its underlying mechanisms through in vivo and in vitro electrophysiological tests, histomorphological examination and molecular biological methods. This project will clarify the efficacy and safety of targeted ablation of cardiac sympathetic neurons for preventing ventricular arrhythmias and sudden cardiac death after myocardial infarction, and may provide a new therapeutic strategy for preventing ventricular arrhythmias and sudden cardiac death after myocardial infarction.

交感神经激活是诱发心肌梗死后室性心律失常和心脏性猝死的重要因素。靶向损毁心交感神经元是一种结前去神经方法，不损伤传入纤维通路，不会发生神经纤维再生和去神经化后超敏反应。初步研究显示，靶向损毁心交感神经元可降低交感神经活性，减少心室交感神经纤维密度。我们的预实验发现，靶向损毁心交感神经元显著抑制星状神经节活性，降低心肌梗死后交感神经重构。本项目首次提出靶向损毁心交感神经元预防心肌梗死后室性心律失常和心脏性猝死的新思路。我们将构建犬心肌梗死及心肌梗死后心脏性猝死动物模型，观察靶向损毁心交感神经元对心室和心房电生理性质及窦房结和房室结功能的影响，并通过在体电生理研究、细胞电生理研究、组织形态学研究和分子生物学研究等技术探讨其作用机制，明确其预防心肌梗死后室性心律失常和心脏性猝死的有效性和安全性，为预防心肌梗死后室性心律失常和心脏性猝死提供新策略。

心肌梗死（MI）后出现的恶性室性心律失常是心脏性猝死（SCD）的主要原因之一，自主神经再平衡策略可以减少MI后SCD的发生。本研究中，左侧星状神经节（LSG）内注射霍乱毒素B亚单位-肥皂草素轭合物（CTB-SAP），选择性消融交感节前神经元以减少交感节后神经元数目，实现靶向损毁心交感神经元（TACSN）的作用。.主要研究内容.将38只成年雄性犬随机分为假手术组（n=8只）、MI组（n=15只）及MI-TACSN组（n=15只）。经微导管于冠状动脉前降支内注射明胶海绵栓塞剂构建MI模型。MI后1周，LSG内注射CTB-SAP以实现TACSN。MI术后5周，分析各组犬LSG神经活性和功能。测定心室各部位有效不应期、动作电位时程（APD）、APD回复曲线、APD交替阈值。测量左室射血分数（LVEF）、左室短轴缩短率（LVFS）、左室收缩末压（LVESP）和左室舒张末压（LVEDP）。利用醋酸甲酚紫染色计数LSG内神经元。测定梗死周边区酪氨酸羟化酶（TH）、生长相关蛋白-43（GAP43）阳性神经纤维，并分析Collagen I和Collagen III蛋白表达水平，评估血清去甲肾上腺素（NE）、心房钠尿肽（ANP）及脑钠肽（BNP）水平。.重要结果和关键数据 .1）TACSN可以减少LSG内神经元数目（31.3±10.9 vs. 156.3±12.0 /mm2, P < 0.05），并显著抑制MI后全身性和LSG交感神经的异常激活（NE：233.1±19.1 vs. 296.7±17.1ng/L, P < 0.05）。.2）TACSN显著改善MI后心脏神经重构（TH: 0.6±0.2 vs. 1.1±0.3%, P < 0.05；GAP43: 0.5±0.1 vs. 1.0±0.3%, P < 0.05）和电重构（ERP离散度：0.04±0.02 vs. 0.08±0.03, P＜0.05）。.3）TACSN显著抑制MI后心脏结构重构（collagen I：0.46±0.06 vs. 0.68±0.05, P < 0.05）并改善心脏功能（LVEF：51.13±3.91 vs. 40.88±2.41%, P < 0.05）。.科学意义.TACSN可显著改善MI后心室电生理性质和心脏神经重构，并改善不良的心脏结构重构，延缓心力衰竭发展进程。