Llewelyn M B, Azami J, Roberts M H
Neuropharmacology. 1986 Jul;25(7):727-35. doi: 10.1016/0028-3908(86)90088-2.
The microinjection of morphine into the nucleus raphe magnus (NRM) increased the tail-flick latency of rats but also increased the size of noxiously-evoked responses of dorsal horn neurones. Electrical stimulation of the raphe magnus reduced the response size of the same neurons to noxious stimulation. To control for the possibility that morphine had a membrane stabilising action upon cells in the raphe magnus, tetracaine was injected into the raphe magnus and found to reduce the size of noxiously-evoked responses of dorsal horn cells. Bilateral lesions of the dorsolateral funiculus reduced the effect on tail-flick latency of morphine injected into the raphe magnus, indicating that morphine was causing antinociception by an effect on descending systems. This effect of morphine was fundamentally different however from the effects of electrical stimulation. Antinociception may result from different mechanisms within the raphe magnus nucleus, affected by morphine and electrical stimulation.
向中缝大核（NRM）微量注射吗啡可增加大鼠的甩尾潜伏期，但也会增加背角神经元有害刺激诱发反应的幅度。中缝大核的电刺激可减小相同神经元对有害刺激的反应幅度。为了控制吗啡对中缝大核细胞具有膜稳定作用的可能性，将丁卡因注入中缝大核，发现其可减小背角细胞有害刺激诱发反应的幅度。双侧背外侧索损伤减弱了注入中缝大核的吗啡对甩尾潜伏期的影响，表明吗啡通过作用于下行系统产生抗伤害感受。然而，吗啡的这种作用与电刺激的作用根本不同。抗伤害感受可能源于中缝大核内受吗啡和电刺激影响的不同机制。
