低强度耳屏迷走神经刺激通过减轻心房内质网应激缓解长程起搏诱导的心房颤动

Transcutaneous Auricular Vagus Nerve Stimulation Relieves Long-Term Pacing-Induced Atrial Fibrillation by Reducing Atrial Endoplasmic Reticulum Stress

目的探讨低强度耳屏迷走神经刺激(ta-VNS)在长程起搏诱导的心房颤动(Af)犬模型中的作用及潜在机制。方法18只成年健康Beagle犬随机分为3组:假手术组、Af组和Af+ta-VNS组。所有犬均植入右心房快速起搏器,除假手术组不起搏外其余组给予600次/min参数起搏,持续4周。Af+ta-VNS组于4周后给予ta-VNS直至第8周末,其余组给予假刺激。所有实验犬分别于基线期、4周末、8周末采集静脉血检测血清乙酰胆碱、肾上腺素及去甲肾上腺素浓度;评估左/右心房内径和左室射血分数;检测心房有效不应期、Af易损窗、Af诱发率及Af平均持续时间等电生理指标。实验结束后取心房组织行TUNEL染色并检测GRP78、PERK、p-PERK、eIF2α、p-eIF2α、CHOP等内质网应激相关蛋白表达水平。结果血清学检测显示Af+ta-VNS组血清乙酰胆碱水平升高,肾上腺素及去甲肾上腺素水平降低(P<0.05)。在体电生理检测显示,ta-VNS可有效降低Af模型犬的Af易损窗、Af诱发率及Af持续时间并恢复心房有效不应期(P<0.05);同时ta-VNS可有效缩小左/右心房内径、降低心率并恢复射血分数(P<0.05)。分子生物学检测显示,Af+ta-VNS组可有效减少心房肌细胞凋亡,并降低GRP78、PERK、p-PERK、eIF2α、p-eIF2α、CHOP等内质网应激相关蛋白表达水平(P<0.05)。结论ta-VNS可通过抑制内质网应激及心肌细胞凋亡,减轻长程起搏诱导的心房重塑。

Objective To investigate the effect and potential mechanism of transcutaneous auricular vagus nerve stimulation(ta-VNS)on long-term pacing-induced atrial fibrillation(Af)in dog models.Methods Eighteen healthy adult Beagle dogs were randomly divided into three groups:sham-operated group,Af group and Af+ta-VNS group.All dogs were implanted with rapid pacemakers in the right atrium.Except the sham-operated group,the other groups were given 600 beats/min pacing for 4 weeks.The Af+ta-VNS group was given ta-VNS after 4 weeks until the end of 8th week,while the other groups were given sham stimulation.Venous blood was collected from all experimental dogs at the baseline period,the end of the 4th week and the end of the 8th week to detect the concentration of serum acetylcholine,epinephrine and norepinephrine.Left/right atrial diameters and left ventricular ejection fraction were evaluated.Electrophysiological indexes such as the atrial effective refractory period,vulnerable window of Af,induction rate of Af and average duration of Af were detected.At the end of the experiment,the atrial tissue was taken for TUNEL staining and the expression levels of endoplasmic reticulum stress(ERS)related proteins such as GRP78,PERK,p-PERK,eIF2α,p-eIF2αand CHOP were detected.Results Serological examination showed that the serum acetylcholine level increased and the serum epinephrine and norepinephrine levels decreased in Af+ta-VNS group(P<0.05).In vivo electrophysiological examination showed that ta-VNS could effectively reduce vulnerable window of Af,Af induction rate,duration of Af and restore atrial effective refractory period in dogs with Af(P<0.05).At the same time,ta-VNS can effectively reduce the left/right atrial diameter,reduce heart rate and restore ejection fraction(P<0.05).Molecular biological analysis showed that Af+ta-VNS could effectively reduce the apoptosis of atrial myocytes and the expression of GRP78,PERK,p-PERK,eIF2α,p-eIF2α,CHOP and other ERS related proteins(P<0.05).Conclusion ta-VNS can reduce long-term pacing-induced Af by inhibiting ERS and cardiomyocyte apoptosis.