Inflammation increases the excitability of masseter muscle afferents
Inflammation increases the excitability of masseter muscle afferents
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DOI：
10.1016/j.neuroscience.2006.03.049
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发表时间：
2006-01-01
期刊：
影响因子：
3.3
通讯作者：
Gold, M. S.
中科院分区：
文献类型：
--
作者：
Harriott, A. M.;Dessem, D.;Gold, M. S.
颞下颌疾病是与咀嚼肌和/或颞下颌关节的慢性口面部疼痛相关的主要健康问题。有证据表明，支配咀嚼肌的初级传入神经的变化可能导致颞下颌关节紊乱。然而，对于控制这些肌肉传入神经的兴奋性及其对炎症的反应的机制却很少有系统的研究。在本研究中，我们测试了以下假设：炎症增加了支配大鼠咬肌的感觉神经元的兴奋性，并且这些变化背后的离子机制是这些神经元所独有的。我们检查了肌内注射完全弗氏佐剂后炎症引起的三叉神经节肌肉神经元兴奋性的变化。完成弗氏佐剂注射三天后，使用全细胞膜片钳技术研究了急性解离、逆行标记的三叉神经节神经元。完全弗氏佐剂诱导的炎症与神经元兴奋性的增加相关，其特征在于流变碱的显着减少和通过去极化电流注射评估的刺激反应函数的斜率增加。兴奋性的增加与超极化后动作电位下降速率和动作电位持续时间的显着降低相关。兴奋性和动作电位波形的这些变化与激活电压依赖性和电压门控 K+ 电流的稳态可用性的显着变化以及稳态失活时电压门控 K+ 电流密度的显着降低相关。这些数据表明 K+ 通道亚型可能为治疗肌肉发炎引起的疼痛提供新的靶点。这些结果还支持这样的假设，即身体特定区域产生的疼痛的潜在机制是独特的，这表明即使没有必要，也可以通过特定的治疗干预来治疗源自身体不同部位的疼痛。 (c) 2006 年国际广播组织。由爱思唯尔有限公司出版。保留所有权利。
Temporomandibular disorder is a major health problem associated with chronic orofacial pain in the masticatory muscles and/or temporomandibular joint. Evidence suggests that changes in primary afferents innervating the muscles of mastication may contribute to temporomandibular disorder. However, there has been little systematic study of the mechanisms controlling the excitability of these muscle afferents, nor their response to inflammation. In the present study, we tested the hypotheses that inflammation increases the excitability of sensory neurons innervating the masseter muscle of the rat and that the ionic mechanisms underlying these changes are unique to these neurons. We examined inflammation-induced changes in the excitability of trigeminal ganglia muscle neurons following intramuscular injections of complete Freund's adjuvant. Three days after complete Freund's adjuvant injection acutely dissociated, retrogradely labeled trigeminal ganglia neurons were studied using whole cell patch clamp techniques. Complete Freund's adjuvant-induced inflammation was associated with an increase in neuronal excitability marked by a significant decrease in rheobase and increase in the slope of the stimulus response function assessed with depolarizing current injection. The increase in excitability was associated with significant decreases in the rate of action potential fall and the duration of the action potential after hyperpolarization. These changes in excitability and action potential waveform were associated with significant shifts in the voltage-dependence of activation and steady-state availability of voltage-gated K+ current as well as significant decreases in the density of voltage-gated K+ current subject to steady-state inactivation. These data suggest that K+ channel subtypes may provide novel targets for the treatment of pain arising from inflamed muscle. These results also support the hypothesis that the underlying mechanisms of pain arising from specific regions of the body are unique suggesting that it may be possible, if not necessary to treat pain originating from different parts of the body with specific therapeutic interventions. (c) 2006 IBRO. Published by Elsevier Ltd. All rights reserved.