Du Huan-Ji, Kitahata Luke M, Thalhammer Johann G, Zimmermann Manfred
II. Physiologisches Institut, Universität Heidelberg, Im Neuenheimer Feld 326, D - 6900 HeidelbergF.R.G.
Pain. 1984 Jul;19(3):249-257. doi: 10.1016/0304-3959(84)90003-4.
The descending inhibitions produced by morphine microinjection and electrical stimulation in the nucleus raphe magnus (NRM) on dorsal horn neurons excited by noxious heating of the skin and/or electrical stimulation of hind limb nerves were examined in the cat. The responses to A-volleys were inhibited to 60.1% (mean, n = 9), those to C-volleys to 64.8% of control (mean, n = 6) and responses to skin heating to 25.3% (mean, n = 8) by electrical NRM stimulation. Morphine (e.g., 10 or 20 micrograms) microinjected into the NRM markedly reduced the responses elicited by afferent C-fiber stimulation (mean 55.6%, n = 8) and the responses to noxious skin heating (mean 38.1%, n = 8), while responses to A-volleys in hind limb nerves were less attenuated (mean 73.6%, n = 8). The effects of morphine were partially or completely blocked by microinjection (10 micrograms) of naloxone into the NRM. It is concluded that morphine microinjection into the NRM generates descending inhibition on the transmission of nociceptive information in the dorsal horn of the spinal cord. This may partly explain the mechanisms of morphine analgesia.
在猫身上研究了向中缝大核（NRM）微量注射吗啡和电刺激所产生的下行抑制作用，该抑制作用作用于因皮肤有害热刺激和/或后肢神经电刺激而兴奋的脊髓背角神经元。通过NRM电刺激，对A波群的反应被抑制至对照的60.1%（平均值，n = 9），对C波群的反应被抑制至对照的64.8%（平均值，n = 6），对皮肤热刺激的反应被抑制至25.3%（平均值，n = 8）。向NRM微量注射吗啡（例如10或20微克）可显著降低传入C纤维刺激所引发的反应（平均值55.6%，n = 8）以及对有害皮肤热刺激的反应（平均值38.1%，n = 8），而后肢神经A波群的反应减弱程度较小（平均值73.6%，n = 8）。向NRM微量注射纳洛酮（10微克）可部分或完全阻断吗啡的作用。得出的结论是，向NRM微量注射吗啡会对脊髓背角伤害性信息的传递产生下行抑制。这可能部分解释了吗啡镇痛的机制。
