Dougherty M P, Willis D W, Lenz A F
Departments of Neurosurgery and Neuroscience, Johns Hopkins University School of Medicine, Meyer 5-109, 600 N. Wolfe Street, Baltimore, MD 21287-7509, USA Department of Anatomy and Neuroscience, University of Texas Medical Branch, 301 University Blvd, Galveston, Texas 77555-1069, USA.
Pain. 1998 Aug;77(2):129-136. doi: 10.1016/S0304-3959(98)00079-7.
A secondary zone of cutaneous hyperalgesia in humans is characterized by increased pain to mechanical stimuli. In contrast, the perception of heat stimuli delivered to a secondary zone of hyperalgesia in humans often shows a paradoxical decrease in magnitude. A number of studies have shown that the responses of spinal cord neurons to cutaneous mechanical stimuli after peripheral injury model well the mechanical hyperalgesia. However, the responses of dorsal horn neurons to thermal stimuli after peripheral injury have not been as carefully studied. The present study examined the effects of intradermal capsaicin on the responses of spinal sensory projection neurons to cutaneous mechanical and thermal stimuli. Our observations indicate that the responses of identified sensory projection neurons to heat are transiently reduced at the same time that responses of these cells to mechanical stimuli are increased. These results confirm a role for sensory projection cells in signaling the sensory discriminative aspects of pain in humans and underscore the emerging complexity of dorsal horn circuitry and sensory processing.
人类皮肤痛觉过敏的次级区域的特征是对机械刺激的疼痛增加。相比之下，传递到人类痛觉过敏次级区域的热刺激的感知强度往往会出现反常降低。多项研究表明，外周损伤后脊髓神经元对皮肤机械刺激的反应很好地模拟了机械性痛觉过敏。然而，外周损伤后背角神经元对热刺激的反应尚未得到如此仔细的研究。本研究检测了皮内注射辣椒素对脊髓感觉投射神经元对皮肤机械和热刺激反应的影响。我们的观察结果表明，在这些细胞对机械刺激的反应增加的同时，已鉴定的感觉投射神经元对热的反应会暂时降低。这些结果证实了感觉投射细胞在传递人类疼痛的感觉辨别方面的作用，并强调了背角神经回路和感觉处理中日益复杂的情况。
