迷走神经在生理性缺血训练改善心力衰竭大鼠心功能中的作用

关键词：心力衰竭  生理性缺血训练  迷走神经  心肌重构  乙酰胆碱M2受体

Keywords:heart failure  physiological ischemic training  vagus nerve  myocardial remodeling  acetylcholine M2 receptor

摘要：

      摘要 目的：探讨生理性缺血训练（PIT）改善心力衰竭（心衰）大鼠心功能过程中迷走神经的作用及其发挥效应的分子生物学机制。 方法：30只大鼠随机分为假手术组（SO组）、单纯心衰组（HF组）、生理性缺血训练组（PIT组）、乙酰胆碱M2受体拮抗剂组（M2R-组）及乙酰胆碱M2受体激动剂组（M2R+组），每组6只。SO组按照心衰大鼠模型建立步骤，将线穿过左冠状动脉前降支不结扎，不训练；HF组为心衰大鼠模型，不训练；PIT组在HF组基础上进行训练，每次缺血5min，再灌注5min，5次/天，5天/周，持续8周；M2R-组及M2R+组分别在PIT组基础上每天尾静脉注射乙酰胆碱M2受体特异性拮抗剂（0.5mg/kg， i.v.）及激动剂（0.2mg/kg， i.v.）。8周训练结束后，采用小动物二维超声系统检测心功能，Masson染色检测心肌梗死面积，qRT-PCR及Western Blot分别检测Bcl-2、Bax、MMP-9及TIMP-1的mRNA和蛋白表达水平，Ellman法检测乙酰胆碱酯酶活性，ELISA法检测去甲肾上腺素浓度。 结果：8周训练后，PIT及M2R+组的左室射血分数（LVEF）、Bcl-2、Bcl-2/Bax的值及TIMP-1显著高于HF组和M2R-组（P<0.05）；相反地，心肌梗死面积、Bax、MMP-9及MMP-9/TIMP-1的值则显著低于HF组和M2R-组（P<0.05）。PIT组、M2R-组及M2R+组乙酰胆碱酯酶活性显著高于HF组（P<0.01），前者三组组间无显著差异（P>0.05）。与SO组相比，其余各组去甲肾上腺素浓度显著升高（P<0.01），但各组组间均无显著差异（P>0.05）。乙酰胆碱酯酶活性与Bcl-2/Bax及LVEF，Bcl-2/Bax与LVEF呈正相关，乙酰胆碱酯酶活性与MMP-9/TIMP-1，MMP-9/TIMP-1与LVEF呈负相关（P<0.001）。 结论：PIT可以通过提高迷走神经活性，减少心肌凋亡，减轻心肌间质纤维化，从而抑制心肌重构，改善心衰大鼠的心功能，该保护过程由乙酰胆碱M2受体介导。

Abstract:

      Abstract Objective： To explore the role of vagus nerve in the process of physiological ischemic training（PIT） improving cardiac function in rats with heart failure and underlying molecular biological mechanism. Method： Thirty rats were randomized into sham operation (SO)， heart failure (HF)， physiological ischemic training (PIT)， acetylcholine M2 receptor antagonist (M2R-) and acetylcholine M2 receptor agonist (M2R+) group. In SO group，according to the heart failure model， the line was crossed through the anterior descending branch of the left coronary artery without ligation， no training. HF group was established as heart failure model，no training. PIT group was given training on the basis of HF group accompanied with ischemia for 5min and reperfusion for 5min each time， 5 times per day， 5 days per week， for 8 weeks. On the basis of PIT group，M2R- group and M2R+ group were given acetylcholine M2 receptor specific antagonist (0.5mg/kg， i.v.) and agonist (0.2mg/kg， i.v.) by tail vein injection every day respectively. After 8 weeks training， animal two-dimensional ultrasound system was used to detect cardiac function，myocardial infarction area was detected by Masson staining， mRNA and protein expression of Bcl-2， Bax， MMP-9 and TIMP-1 were detected by qRT-PCR and Western Blot respectively， acetylcholinesterase activity was detected by Ellman， and noradrenaline concentration was detected by ELISA. Result： After 8 weeks training， left ventricular ejection fraction (LVEF)， Bcl-2， Bcl-2/Bax and TIMP-1 in PIT and M2R+ groups were significantly higher than those in HF group and M2R- group (P<0.05). In contrast， the myocardial infarction area， Bax， MMP-9 and MMP-9/TIMP-1 were significantly lower than those in HF group and the M2R-group (P<0.05). The activity of acetylcholinesterase in PIT group， M2R- group and M2R+ group was significantly higher than those in HF group (P<0.01). However， there was no significant differences between the former three groups (P>0.05). The concentrations of norepinephrine were significantly higher in the other groups than in SO group (P<0.01). On the contrary， there was no significant differences between the other groups (P>0.05). The activity of acetylcholinesterase was positively correlated with Bcl-2/Bax and LVEF；Bcl-2/Bax was positively correlated with LVEF； the activity of acetylcholinesterase was negatively correlated with MMP-9/TIMP-1； MMP-9/ TIMP-1 was negatively correlated with LVEF (P<0.001). Conclusion： PIT can upregulate the activity of vagus nerve， reduce myocardial apoptosis， and alleviate myocardial interstitial fibrosis， thereby inhibiting myocardial remodeling and improving cardiac function in rats with heart failure. This protective process is mediated by acetylcholine M2 receptor.