Involvement of ATP and its receptors on nociception in rat model of masseter muscle pain
Involvement of ATP and its receptors on nociception in rat model of masseter muscle pain
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DOI：
10.1016/j.pain.2007.04.006
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发表时间：
2008-01-01
期刊：
影响因子：
7.4
通讯作者：
Sugiura, Yasuo
中科院分区：
文献类型：
--
作者：
Shinoda, Masamichi;Ozaki, Norlyuki;Sugiura, Yasuo
咬肌疼痛被认为是颞下颌关节紊乱病的突出症状，其确切机制尚不清楚，尽管临床上已知肌肉过度收缩会导致咬肌压痛。P2 X（3）受体（P2 X（3）Rs）在感觉神经元的痛觉信号传导中起重要作用。我们在一个新建立的大鼠咬肌痛模型中确定了P2 X（3）R在压力痛和机械性痛觉过敏中的作用。咬肌的疼痛通过压力疼痛阈值（PPT）来评估，压力疼痛阈值（PPT）被定义为引起头部退缩所需的压力的量。在幼稚动物中，吗啡全身治疗与PPT增加相关。在咬肌中施用P2 XR激动剂或拮抗剂后检查PPT的变化。咬肌注射α，β-meATP（P2 X（1，3，2/3）R特异性激动剂）诱导的行为反应显著大于其载体。这种增强的反应被α，β-meATP与PPADS（P2 X（1，2，3，5，1/5，2/3）R特异性拮抗剂）的共同应用完全阻断。电刺激引起咬肌过度收缩。施加咬肌示出了显着减少的PPT，表明肌肉的机械痛觉过敏的诱导。此外，PPADS的管理，以发挥咬肌产生了一个完整的恢复减少PPT。免疫组化显示，三叉神经节过度收缩时，支配咬肌的P2 X（3）R阳性神经元数量增加。提示P2 X3 R在咬肌过度收缩引起的压迫痛和机械性痛觉过敏中起重要作用。(c)2007年国际疼痛研究协会。Elsevier B. V.出版，保留所有权利。
The exact mechanism of the masseter muscle pain recognized as a prominent symptom in temporomandibular disorders remains unclear, although it is clinically known that excessive muscular contraction causes tenderness in masseter muscles. It has been demonstrated that P2X(3) receptors (P2X(3)Rs) in sensory neurons play a role in pain signaling from the periphery. We determined the role of P2X(3)R on pressure pain and mechanical hyperalgesia in a newly developed rat model of masseter muscle pain. The pain in the masseter muscle was assessed by the pressure pain threshold (PPT), which was defined as the amount of pressure required to induce head flinching. In naive animals, systemic treatment with morphine was associated-with increase of PPTs. Changes in PPTs were examined after administration of P2XR agonists or antagonists into the masseter muscle. The masseter muscle injection of alpha,beta-meATP (P2X(1,3,2/3)R-specific agonist) induced a significantly greater behavioral response than its vehicle. This enhanced response was completely blocked by the co-application of alpha,beta-meATP with PPADS (P2X(1,2,3,5,1/5,2/3)R-specific antagonist). Excessive contraction in masseter muscle was produced by electrical stimulation. The exerted masseter muscles showed a significant reduction in PPTs indicating the induction of mechanical hyperalgesia of the muscle. Moreover, administration of PPADS to the exerted masseter muscles produced a complete recovery of reducing PPT. Immunohistochemically, the number of P2X(3)R-positive neurons innervating the masseter muscles increased in the excessively contracted condition in trigeminal ganglia. Our results suggested that P2X3R plays an important role in pressure pain and mechanical hyperalgesia in masseter muscle caused by excessive muscular contraction. (c) 2007 International Association for the Study of Pain. Published by Elsevier B.V. All rights reserved.