Bian D, Ossipov M H, Zhong C, Malan T P, Porreca F
Department of Pharmacology, University of Arizona Health Sciences Center, Tucson 85724, USA.
Neurosci Lett. 1998 Jan 30;241(2-3):79-82. doi: 10.1016/s0304-3940(98)00051-2.
Spinal nerve ligation produces signs of neuropathic pain in rats. Different neuronal pathways may underlie the abnormal sensory responses to thermal and tactile stimuli. Here, the possibility that local circuitry in the spinal cord and/or spinal-supraspinal loops might be involved in tactile allodynia and thermal hyperalgesia of the hindpaws was investigated by transecting the spinal cord of sham-operated or L5/L6 nerve ligated rats. Spinal transection completely abolished tactile allodynia in ligated rats. Thermal nocifensive responses were present after transection in ligated and sham-operated rats. Thermal hyperalgesia of the hindpaws was not evident in spinal transected, ligated rats. Tail-withdrawal responses to tactile probing were very robust after spinal transection in both groups, demonstrating loss of descending inhibition. These observations suggest that thermal hyperalgesia of the paw seen after nerve injury involves both spinal and supraspinal circuits, while tactile allodynia depends on a supraspinal loop. This difference may reflect afferent inputs associated with different fiber types.
脊髓神经结扎会使大鼠出现神经性疼痛的症状。不同的神经元通路可能是对热刺激和触觉刺激异常感觉反应的基础。在此，通过切断假手术或L5/L6神经结扎大鼠的脊髓，研究脊髓局部回路和/或脊髓-脊髓上环路可能参与后爪触觉异常性疼痛和热痛觉过敏的可能性。脊髓横断完全消除了结扎大鼠的触觉异常性疼痛。在横断后，结扎和假手术大鼠均出现热防御反应。脊髓横断的结扎大鼠后爪的热痛觉过敏不明显。两组大鼠脊髓横断后对触觉探查的甩尾反应都非常强烈，表明下行抑制丧失。这些观察结果表明，神经损伤后出现的爪部热痛觉过敏涉及脊髓和脊髓上回路，而触觉异常性疼痛则依赖于脊髓上环路。这种差异可能反映了与不同纤维类型相关的传入输入。
