Tal M, Bennett G J
Neurobiology and Anesthesiology Branch, National Institute of Dental Research, National Institutes of Health, Bethesda, MD 20892.
Neurosci Lett. 1993 Mar 5;151(1):107-10. doi: 10.1016/0304-3940(93)90058-s.
Dextrorphan (DEX), a non-competitive NMDA receptor antagonist, was given intraperitoneally and intrathecally (i.t.) to rats with an experimental painful peripheral mononeuropathy. The neuropathy was created by placing loosely constrictive ligatures around the sciatic nerve, and the pain threshold was studied with the paw-flick method. The effects of DEX on the neuropathic heat-evoked hyperalgesia that follows this nerve injury were determined during the period of peak symptom severity. DEX given i.p. relieved heat-evoked hyperalgesia in a dose-dependent manner without producing motor impairment. The highest doses tested (12.5 and 25 mg/kg) produced a large but incomplete block (about 50%). DEX had no effect on the responsiveness of the paw on the control side. i.t. injection of 20 micrograms DEX completely blocked heat-hyperalgesia when tested 1 h later; again, the effect was achieved without motor impairment and without any change on the control side. These results suggest that DEX may be useful in the treatment of human neuropathic pain.
右啡烷（DEX）是一种非竞争性N-甲基-D-天冬氨酸（NMDA）受体拮抗剂，通过腹腔注射和鞘内注射给予患有实验性疼痛性外周单神经病的大鼠。通过在坐骨神经周围放置宽松的缩窄结扎线来制造神经病，并采用甩尾法研究疼痛阈值。在症状严重程度达到峰值期间，确定DEX对这种神经损伤后神经性热诱发痛觉过敏的影响。腹腔注射DEX以剂量依赖性方式减轻热诱发的痛觉过敏，且不产生运动障碍。测试的最高剂量（12.5和25mg/kg）产生了较大但不完全的阻断作用（约50%）。DEX对对照侧爪子的反应性没有影响。鞘内注射20微克DEX在1小时后测试时完全阻断了热痛觉过敏；同样，该效果在没有运动障碍且对照侧没有任何变化的情况下实现。这些结果表明，DEX可能对治疗人类神经性疼痛有用。
