Yamaoka Gotaro, Horiuchi Hideki, Morino Tadao, Miura Hiromasa, Ogata Tadanori
Spine Center, Ehime University Hospital, Tohon, Ehime 791-0295, Japan.
J Orthop Sci. 2013 Jan;18(1):130-6. doi: 10.1007/s00776-012-0302-0. Epub 2012 Sep 21.
Adenosine is an endogenous neuromodulator in both the peripheral and central nervous systems. Adenosine inhibits pain signals by hyperpolarizing neuronal membrane.
To clarify the effects of adenosine on pain signals, we tested intrathecal adenosine injection in two neuropathic pains (spinal cord compression and chronic constriction of sciatic nerve) and postoperative pain (plantar incision).
In all three kinds of pain models, significant shortening of withdrawal latencies to thermal stimulation were detected from 24 h to 1 week after the surgery. Significant improvements of pain sensation were observed in all three models after intrathecal injection of Cl-adenosine 24 h after surgery. At 72 h after surgery, intrathecal Cl-adenosine injection inhibited hyperalgesia in the two neuropathic pain models but not in the postoperative pain model. Adenosine A1R messenger RNA (mRNA) expression significantly decreased in the plantar incision model. Adenosine A1R protein levels also decreased compared with the other two models and normal control.
These results suggest that adenosine effectively inhibits pain signals in neuropathic pain but is less effective in postoperative pain because of the decrease in adenosine A1 receptors.
腺苷是外周和中枢神经系统中的一种内源性神经调节剂。腺苷通过使神经元膜超极化来抑制疼痛信号。
为阐明腺苷对疼痛信号的影响，我们在两种神经性疼痛（脊髓压迫和坐骨神经慢性缩窄）及术后疼痛（足底切口）模型中测试了鞘内注射腺苷。
在所有三种疼痛模型中，术后24小时至1周期间均检测到对热刺激的缩足潜伏期显著缩短。术后24小时鞘内注射氯腺苷后，在所有三种模型中均观察到痛觉有显著改善。术后72小时，鞘内注射氯腺苷在两种神经性疼痛模型中抑制了痛觉过敏，但在术后疼痛模型中未起作用。在足底切口模型中，腺苷A1R信使核糖核酸（mRNA）表达显著降低。与其他两种模型及正常对照相比，腺苷A1R蛋白水平也降低。
这些结果表明，腺苷在神经性疼痛中能有效抑制疼痛信号，但在术后疼痛中效果较差，这是由于腺苷A1受体减少所致。
