P2Y12 receptors in spinal microglia are required for neuropathic pain after peripheral nerve injury
P2Y12 receptors in spinal microglia are required for neuropathic pain after peripheral nerve injury
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DOI：
10.1523/jneurosci.0323-08.2008
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发表时间：
2008-05-07
影响因子：
5.3
通讯作者：
Inoue, Kazuhide
中科院分区：
文献类型：
--
作者：
Tozaki-Saitoh, Hidetoshi;Tsuda, Makoto;Inoue, Kazuhide
细胞外核苷酸被认为是小胶质细胞用来感知不良生理条件（如神经元损伤）的信号分子。它们通过嘌呤受体起作用，特别是G蛋白偶联的P2Y受体P2Y（12）R。新出现的证据表明，响应神经损伤的激活的脊髓小胶质细胞是导致高度衰弱的慢性疼痛状态（即神经性疼痛）的关键细胞中介。然而，小胶质细胞P2Y（12）Rs在神经病理性疼痛中的作用仍然未知。在这里，我们表明，P2Y（12）R mRNA的表达水平显着增加，在脊髓同侧的神经损伤，这种表达是高度限制离子结合钙适配器分子1阳性小胶质细胞。在神经损伤后，还观察到同侧脊髓中P2Y（12）R蛋白的免疫荧光增加，并且P2Y（12）R阳性细胞用小胶质细胞标记物OX-42双标记。通过鞘内注射其拮抗剂AR-C69931MX阻断脊髓P2Y（12）R可防止触觉异常性疼痛（对无害刺激的疼痛超敏反应）的发生，这是神经性疼痛综合征的标志。此外，缺乏P2ry（12）（P2ry（12）（-/-））的小鼠在神经损伤后显示出受损的触觉异常性疼痛，而基础机械敏感性没有任何变化。此外，对神经损伤大鼠单次鞘内注射AR-C69931MX或口服氯吡格雷（临床上使用的P2Y（12）R阻滞剂）可显著缓解现有的触觉异常性疼痛。总之，我们的研究结果表明，脊髓小胶质细胞中P2Y（12）R的激活可能是神经性疼痛发病机制中的关键事件，并表明阻断小胶质细胞P2Y（12）R可能是治疗神经性疼痛的可行治疗策略。
Extracellular nucleotides have been implicated as signaling molecules used by microglia to sense adverse physiological conditions, such as neuronal damage. They act through purinoceptors, especially the G-protein-coupled P2Y receptor P2Y(12)R. Emerging evidence has indicated that activated spinal microglia responding to nerve injury are key cellular intermediaries in the resulting highly debilitating chronic pain state, namely neuropathic pain. However, the role of microglial P2Y(12)Rs in neuropathic pain remains unknown. Here, we show that the level of P2Y(12)R mRNA expression was markedly increased in the spinal cord ipsilateral to the nerve injury and that this expression was highly restricted to ionized binding calcium adapter molecule 1-positive microglia. An increase in the immunofluorescence of P2Y(12)R protein in the ipsilateral spinal cord was also observed after nerve injury, and P2Y(12)R-positive cells were double labeled with the microglial marker OX-42. Blocking spinal P2Y(12)R by the intrathecal administration of its antagonist AR-C69931MX prevented the development of tactile allodynia ( pain hypersensitivity to innocuous stimuli), a hallmark of neuropathic pain syndrome. Furthermore, mice lacking P2ry(12) (P2ry(12)(-/-)) displayed impaired tactile allodynia after nerve injury without any change in basal mechanical sensitivity. Moreover, a single intrathecal administration of AR-C69931MX or oral administration of clopidogrel (a P2Y(12)R blocker clinically in use) to nerve-injured rats produced a striking alleviation of existing tactile allodynia. Together, our findings indicate that activation of P2Y(12)Rs in spinal microglia may be a critical event in the pathogenesis of neuropathic pain and suggest that blocking microglial P2Y(12)R might be a viable therapeutic strategy for treating neuropathic pain.