摘要目的 探讨α7亚单位N型乙酰胆碱受体(α7nAChR)介导的胆碱能抗炎通路在低强度迷走神经刺激(LL-VNS)抑制心房颤动(房颤)中的作用.方法 18只健康比格犬按随机数字表法分为假手术组(n=6)、LL-VNS组(n=6)和MLA(α7nAChR竞争性拮抗剂)+LL-VNS组(n=6).所有犬右心房刺激(800次/min)6h,连续刺激3h后,假手术组给予心房神经节(GP)注射生理盐水、LL-VNS组给予GP注射生理盐水加LL-VNS、MLA+ LL-VNS组给予GP注射MLA加LL-VNS.所有犬每小时末监测心房及肺静脉有效不应期(ERP)和房颤诱发情况,分别于基线期、3h末、6h末采集静脉血检测白细胞介素-6(IL-6)、肿瘤坏死因子-α(TNF-α)和乙酰胆碱(ACh)水平,实验结束后取心房组织检测IL-6、TNF-α、ACh和核转录因子-κBp65(NF-κBp65)及转录激活子3(STAT3)蛋白表达情况.结果 右心房刺激3h后,3组犬心房及肺静脉ERP显著缩短,房颤诱发率和时间增加.3～6h,假手术组和MLA+ LL-VNS组心房及肺静脉ERP持续缩短,房颤诱发率和时间增加.LL-VNS组3h后ERP逐渐延长,实验终点房颤诱发率和时间与3h相比明显缩短(P＜0.05).6h后LL-VNS组和MLA+ LL-VNS组血清中炎性因子水平显著低于假手术组(pg/ml)[IL-6:(101 ±6)比(119±7),P＜0.05;(102 ±5)比(119±7),P＜0.05;TNF-α:(17.8±1.7)比(22.1±2.0),P＜0.05;(17.9±2.2)比(22.1±2.0),P＜0.05],血清ACh水平高于假手术组(μg/ml)[(151 ±13)比(123±10),P＜0.05;(145 ±5)比(123±10),P＜0.05].LL-VNS组心房组织炎性因子水平明显低于另两组,LL-VNS组和MLA+ LL-VNS组心房组织中ACh水平明显高于假手术组.LL-VNS组心房组织NF-κBp65蛋白水平明显低于假手术组和MLA+ LL-VNS组(P＜0.05),STAT3蛋白水平高于另两组(P＜0.05).结论 LL-VNS可抑制心房肌电重构及房颤的诱发和维持,其机制可能与α7nAChR介导的胆碱能抗炎通路有关.

abstractsObjective To investigate the effect of α7nAChR mediated cholinergic anti-inflammatory pathway on inhibition of atrial fibrillation by low-level vagus nerve stimulation (LL-VNS).Methods Eighteen beagles were randomized into control group (n =6),LL-VNS group (n =6) and methyllycaconitine (MLA) + LL-VNS group (n =6).All the beagles were subjected to rapid atrial pacing at 800 beats/min for 6 hours.And the effective refractory period (ERP) of atriums and pulmonary veins and induced atrial fibrillation (AF) were measured hourly during non-pacing.After cessation of pacing for 3 hours,the beagles in control group were injected with saline into four ganglionated plexis (GPs),the beagles in LL-VNS group were given LL-VNS and saline injected into four GPs,and the beagles in MLA + LL-VNS group were injected with MLA into four GPs combined with LL-VNS.And the levels of tumor necrosis factor-alpha (TNF-α),interleukin-6 (IL-6),and acetylcholine (ACh) in the plasma at baseline condition,3 h and 6 h were measured.At the end of this experiment,atrial tissues were collected to examine the levels of TNF-α,IL-6,ACh,NF-κBp65 and STAT3 proteins.Results During the right atrium pacing for the first 3 hours,the ERPs were gradually decreased while AF inducibility were gradually increased in all groups.At the end of this experiment,compared with the control group and MLA + LL-VNS group,the ERPs in LL-VNS group were increased,and the induced times and duration of AF were significantly decreased.The levels of TNF-α and IL-6 in plasma were all significantly decreased in LL-VNS group and MLA + LL-VNS group when compared with the control group(pg/ml) [IL-6:(101 ±6) vs (119 ±7),P ＜ 0.05;(102±5) vs (119 ±7),P＜0.05;TNF-α:(17.8 ± 1.7) vs (22.1 ±2.0),P＜0.05;(17.9 ± 2.2) vs (22.1 ±2.0),P ＜0.05].And the levels of ACh were higher than in the control group(Iμg/ml) [(151 ± 13) vs (123 ± 10),P ＜ 0.05;(145 ± 5) vs (123 ± 10),P ＜ 0.05].After cessation of pacing for 6 hours,compared with the control groupand MLA + LL-VNS group,the tissue levels of TNF-α and IL-6 were significantly decreased in LL-VNS group (P ＜ 0.05).The concentrations of NF-κBp65 proteins in atrial tissues were lower in the LL-VNS group (P ＜ 0.05),and the levels of STAT3 proteins in those tissues were higher in the LL-VNS group than in thein the two other groups (P ＜ 0.05).Conclusion LL-VNS could inhibit the atrial electrical remodeling and atrial fibrillation induction;cholinergic anti-inflammatory pathway mediated by α7nAChR may be the important mechanism in vagal nerve regulated AF.