中枢神经递质之一去甲肾上腺素(NE)在电针镇痛中的作用早已被重视。有报道表明中枢NE拮抗针刺镇痛

主要根据是针刺镇痛时脑内NE含量减少

毁损NE胞体密集分布的蓝斑及其上行途径

或用双硫醒等抑制NE合成以降低脑的NE含量时

均可增强针刺镇痛;相反

当脑室内注射NE激动剂或注射NE前体使脑内NE含量增高时

则可减弱针刺镇痛。由This paper is designed for investigating the role of descending adrenergic inhibitory pathway in acupuncture analgesia by using iontophoretic technique. Experiments were carried out on adult cats. In most dorsal horn neurons (86%) at lumbar level

the nociceptive responses (Aδ or C response) to saphenous nerve stimulation or nature noxious stimulation were depressed by bilateral electro-acupunture applied on "zusanli". when phentolamine was administred iontophoretically one minute prior to and concurrent with acupuncture

the inhibitory effect of acupuncture was strengthened in some neurons or weakened in others. In general

acupuncture effect was slightly attenuated (n=15

P>0.05). However

the nociceptive response was reduced by iontophoretic phentolamine in all seven neurons. All these results suggest that the adrenergic descending pathway may be involved in acupuncture analgesia

but noradrenaline in spinal cord may also exert its inhibitory effect on the nociceptive transmitting neuron idnirectly in addition to its postsynaptic inhibition. As for the inhibitory effect on nociceptive response by iontophoretic phentolamine

it is supposed that noradrenaline may tonically antagonize some inhibitory effect exerted by other descending inhibitory pathway. The mechanism in detail remains to be further studied.