Kinnman E, Nygårds E B, Hansson P
Department of Rehabilitation Medicine, Karolinska Institute/Hospital, Stockholm, Sweden.
Pain. 1997 Jan;69(1-2):79-85. doi: 10.1016/s0304-3959(96)03257-5.
While the sympathetic nervous system seems to be involved in some pain states, the mechanisms linking the sensory and sympathetic nervous system are unclear. In this study the possible involvement of peripheral alpha-adrenoreceptors in the development of capsaicin induced ongoing pain and mechanical hypersensitivity was examined in humans. Intradermal capsaicin injections in the volar aspect of the arm gave rise to ongoing burning pain and dysesthesia as well as mechanical hypersensitivity. Ongoing pain and pain evoked by von Frey filament stimulation was rated on a numerical rating scale after intradermal capsaicin injection. The area of skin in which von Frey filament stimulation evoked pain was measured. A subcutaneous injection of phentolamine (alpha-adrenoreceptor antagonist) on one side and saline on the other side prior to the capsaicin injection was done to evaluate the role of the peripheral alpha-adrenoreceptors in development of capsaicin induced sensory symptoms and signs. Significantly less ongoing and evoked pain developed on the phentolamine injected side compared to the saline side, the latter in the area adjacent to the capsaicin injection (primary zone) and well outside the area of flare (secondary zone). The area in which pain could be evoked on the phentolamine injected side was restricted to the area of flare and was significantly smaller than on the saline injected side. Mechanical stimulation gave rise to aftersensation and radiation of pain on the saline injected side in all subjects but only in one case on the phentolamine injected side. Peripheral alpha-adrenoreceptors thus seem to be involved in functional changes of primary afferents which contribute to ongoing pain and mechanical stimulus evoked pain.
虽然交感神经系统似乎与某些疼痛状态有关，但感觉神经系统和交感神经系统之间的联系机制尚不清楚。在本研究中，研究了外周α-肾上腺素能受体在辣椒素诱导的持续性疼痛和机械性超敏反应发展过程中的可能作用。在手臂掌侧进行皮内注射辣椒素会引发持续性灼痛、感觉异常以及机械性超敏反应。皮内注射辣椒素后，通过数字评分量表对持续性疼痛和von Frey细丝刺激诱发的疼痛进行评分。测量von Frey细丝刺激诱发疼痛的皮肤区域。在注射辣椒素之前，一侧皮下注射酚妥拉明（α-肾上腺素能受体拮抗剂），另一侧注射生理盐水，以评估外周α-肾上腺素能受体在辣椒素诱导的感觉症状和体征发展中的作用。与注射生理盐水的一侧相比，注射酚妥拉明的一侧出现的持续性疼痛和诱发疼痛明显较少，后者在与辣椒素注射相邻的区域（初级区）以及远超红斑区（次级区）。在注射酚妥拉明的一侧，能够诱发疼痛的区域仅限于红斑区，且明显小于注射生理盐水的一侧。在所有受试者中，机械刺激在注射生理盐水的一侧会引发疼痛后感觉和疼痛放射，但在注射酚妥拉明的一侧仅在一例中出现。因此，外周α-肾上腺素能受体似乎参与了初级传入神经的功能变化，这些变化导致了持续性疼痛和机械刺激诱发的疼痛。
