大鼠心包腔内注射辣椒素诱发c-Fos在孤束核内的表达及迷走神经切断对其表达的影响

c-Fos expression in nucleus tractus solitarius after intrapericardiac injection of capsaicin and the effects of vagus transection in rats

目的探讨心包内注射辣椒素诱发的c-Fos在孤束核(nucleus tractus solitarius,NTS)内的表达,以阐明NTS内的亚核及迷走传入神经在心脏伤害性感受信息传递中的作用。方法 30只雄性SD大鼠随机分为空白对照组、假手术组、溶媒注射组、辣椒素注射组和迷走神经切断组、迷走神经切断加辣椒素注射组;心包内注射的同时,记录心脏伤害性刺激诱发的背斜方肌肌电(EMG)活动,2h后灌注取材,ABC免疫组织化学法染色后拍照,计数NTS内c-Fos阳性神经元数目,进行统计分析。结果溶媒注射组背斜方肌无EMG活动,辣椒素组均有EMG活动(P<0.05);心包腔内注射辣椒素后,NTS内c-Fos表达较空白、假手术和溶媒组明显增多(P<0.05);与迷走神经切断组和辣椒素组比较,迷走神经切断后,心包内注射辣椒素组诱发的背斜方肌EMG活动以及NTS内c-Fos表达明显下降(P<0.05)。结论本研究利用细胞化学方法证明NTS内的联合亚核、背内侧亚核以及腹外侧亚核以及迷走传入神经在心脏伤害性感受的传递中有重要意义。

Objective To explore intra-pericardium capsaicin induced c-Fos expression in nucleus tractus solitaries （NTS） and the effect of vagus transection on capsaicin induced c-Fos expression and cardiac-somatic reflex.Methods Totally 30 male SD rats were randomly divided into blank,sham,vehicle injection,capsaicin injection,vagus transection,and vagus transection plus capsaicin injection groups.Cardiac nociception induced myoelectricity （EMG） activities were recorded while intra-pericardium injection was processed.The brain was removed 2 h after the injection and c-Fos expression was tested by ABC immunohistochemical staining method.Then the number of c-Fos immunopositive neurons in NTS was counted and analyzed statistically.Results ① EMG activities were found in capsaicin group but not in vehcile group.Compared with blank,sham and vehicle groups,intra-pericardium capsaicin induced c-Fos expression in NTS was obviously increased （P＜0.05）; ② Compared with capsaicin group and intact vagus group,intra-pericardium capsaicin induced EMG activities and c-Fos expression in NTS were decreased in vagus transection group （P＜0.05）.Conclusion Commissural nucleus,dorsomedial subnucleus and dorsolateral subnucleus in NTS are involved in cardiac nociception processing,and vagus afferents play an important role in cardiac nociception transmission.