强电针穴位对背角神经元镇痛效应广泛性的中枢机制

实验用雄性大鼠，玻璃微电极细胞外记录Ｔ１２－Ｌ１脊髓背角会聚神经元对后爪伤害性刺激的反应，观察到低强度（２Ｖ）电针作用于与痛源接近的“足三里”穴对背角神经元的伤害性反应有明显的抑制作用，而远隔穴位“下关”穴则无效。而当采用超过Ｃ类纤维阈值１８Ｖ电针时，则远隔穴位“下关”也有明显的镇痛作用。表现为强电针穴位镇痛作用的广泛性。而损毁ＮＲＭ后，强电针（１８Ｖ）远节段“下关”穴的镇痛作用消失，而近节段“足

CENTRAL MECHANISM OF AN EXTENSIVE ANALGESIC EFFECT DUE TO STRONG ELECTROACUPUNCTURE OF ACUPOINT ON SPINAL DORSAL HORN NEURONS

Experiments were performed on male rats. The responses of dorsal horn convergent neurons in spinal cord (T12-L1 ) to noxious stimulation of hind paw were recorded extracellularly with glass microelectrode. When low intensity (2 V) electroacupuncture (EA) was used, the nociceptive responses of convergent neurons were inhibited by EA at "Zusanlin"near noxious stimulation area, but not at "Xiaguan" far from the area. When intensity (18 V) high than the threshold of C fibers EA was applied at the far acupoint "Xiaguan",obvious analgesic effects on convergent neurons were also produced, showing an extensive analgesic effect of strong EA at acupoint. This extensive analgesic effect was abdicated by lesion of nucleus raphe magnus (NRM), but still persisted to some extent by EA at the same segment acupoint "Zusanli" with 18 V or 2 Vintensity.The results suggest that,the extensive analgesia of strong EA at far segment acupoint may be mainly mediated by noxious stimulation through NRM, a negative feedback mechanism modulating pain of supraspinal cord. The analgesia due to 2 V EA at the same segment acupoint may be mainly produced by gate control in spinal cord,but also to some extend by supraspinal cord mechanism.