电针大鼠耳穴“心”等对孤束核升压反射相关神经元电活动的影响

目的:通过观察电针作用于不同穴位对麻醉大鼠不同状态下平均动脉压(MAP)及孤束核(NTS)与升压反射相关神经元放电的影响,证明NTS神经元在针刺和升压反射信号整合中的作用。方法:在麻醉大鼠生理状态下及颈静脉注射脱羟肾上腺素(PE)引起升压反射的状态下,观察电针耳穴"心"及体穴"内关""足三里"对MAP的影响,同时用电生理学单细胞记录的方法记录和鉴别NTS与升压反射相关神经元细胞外放电活动,同步观察上述两种状态下针刺对单细胞放电的影响。结果:颈静脉注射PE引起升压反射,NTS神经元活动对升压反射的反应以兴奋为主。麻醉大鼠生理状态下和PE引起升压平台期时,电针耳穴"心"和体穴"足三里"能降低大鼠的MAP(P<0.001,P<0.05),"内关"无明显作用。电针3个穴位均能增加大鼠生理状态和升压平台期状态NTS升压反射相关神经元的放电活动,在两种血压状态下电针耳穴"心"和体穴"足三里"引起神经元放电增加的百分比均大于"内关"(P<0.05)。结论:NTS内存在升压反射相关神经元,这类神经元被耳穴"心"及体穴"足三里"激活的百分比与"内关"相比更为显著,与针刺耳穴"心"及体穴"足三里"引起的降压效应反应相一致,说明在NTS内针刺和加压反射信号发生整合。

Effect of electroacupuncture on electrical activities of pressor reflex related neurons in the nucleus of tractus solitarii (NTS) in rats

Objective To observe the effect of electroacupuncture(EA)of auricular point "Xin"(Heart),"Neiguan"(PC 6) and "Zusanli"(ST 36) on electrical activities of the pressor reflex-related neurons in the nucleus of the solitary tract(NTS)in rats.Methods A total of 47 SD rats were used in the present study.Extracellular electrical activities of neurons in the NTS(AP:1.0 mm,Left and right:0-1.0 mm,depth:0.3-0.8 mm)were recorded by using glass microelectrodes(10-15 MΩ).Carotid arterial pressure changes were monitored and recorded by using a pressure transducer.EA(2 mA,10 Hz,duration: 500 ms)was randomly applied to the left auricular point "Xin","Neiguan"(PC 6)and "Zusanli"(ST 36) for 30 s,respectively.Elevation of arterial pressure was induced by intravenous injection of Phenylephrine(PE,6-12 μg/kg,2 μg/mL).Results Of the 67 NTS neurons,15 were activated by intravenous injection of PE(which were called as pressor reflex-related neurons).Following EA of the auricular point "Xin" and ST 36,the mean arterial pressure(MAP) levels in normal rats and PE-induced MAP increase rats were lowered significantly(P<0.001,P<0.05).Concomitantly,the firing rates of pressor reflex-related NTS neurons were increased considerably by EA stimulation of auricular point "Xin" and ST 36,but not by EA of PC 6.EA of PC 6 had no apparent influence on MAP in normal rats and in PE-induced MAP increase rats(P>0.05).Conclusion Electroacupuncture stimulation of auricular point "Xin" and "Zusanli"(ST 36) can lower MAP in normal rats and PE-induced MAP elevation rats,and enhance pressor reflex induced increase of firing rates of NTS neurons,suggesting an interaction between signals from electroacupuncture sti-mulation of "Xin" and "Zusanli"(ST 36) and from cardiovascular activities in the NTS neurons.