中缝大核(NRM)是下行5-羟色胺(5-HT)能痛抑制系统的起点

富有去甲肾上腺素(NA)能神经末梢。实验证明:NRM内微电泳NA可抑制NRM神经元放电

NRM内微量注射α受体阻断剂(酚妥拉明)可以加强镇痛

提示NRM内的NA能神经末梢可通过抑制NRM-脊髓神经元起对抗镇痛的作用。但关于这类NA能末梢的来源虽有报道

尚未最后定论。鉴This study was carried out in awake curarized rats under artificial re- spiration. Experiments showed that excitation of neurons of A5 area (whe- re noradrenergic neurons concentrate) by local microinjection of sodium glu- tamate inhibited unit discharge of nucleus raphe magnus

while excitation of locus coeruleus by electro-stimulation or microinjection of sodiumlut amgate had no significant effect on unit discharge of nucleus raphe magnus.