Regulation of masticatory myalgia development by distinct trigeminal neuron subtypes innervating masseter muscle

项目总结/摘要 颞下颌关节紊乱病影响咀嚼肌（TMDM）是最常见的一组， 慢性口面疼痛由咬肌（MM）引起的TMDM慢性疼痛是常见的。我 长期目标是阐明控制TMDM慢性化发展的潜在机制 了解支配MM的神经元的功能和TMDM诱导的可塑性 证明小鼠和灵长类动物的MM主要由具有独特的神经传导的有髓鞘A纤维支配。 电生理特性和受体组成。为了进一步揭开这些神经元的身份 我们进行了单细胞RNA测序并鉴定了支配MM的独特类型的神经元。 选择性标记物可用于这些神经元簇的活性的特异性操纵。主要 该建议的目的是确定MM支配TG神经元群在神经元凋亡过程中的作用。 TMDM慢性化。这个提议的中心假设是，支配MM的神经元具有特化的 神经元类型依赖性的TMDM慢性化和进展的不同贡献 TMDM期间机械门控反应的独特可塑性。为了验证这一假设，我们新开发的 将采用小鼠慢性咬肌疼痛（肌痛）的临床相关模型。目标1将定义 通过测量不同类型的神经元支配MM在TMDM发展中的作用， 机械性超敏反应，使用鬼脸评分、von Frey、条件性位置回避和咬合力。做 因此，我们将利用转基因小鼠品系的可用性和我们的单细胞数据来操纵神经元。 活动的特定组的TG神经元支配MM.设计师受体专门激活的 设计药物（DREADD）将用于抑制神经元活动。目标2将检查TMDM的影响 我们的单细胞RNA测序数据显示， 表明神经支配MM的神经元组都表达机械门控PIEZO-2通道，但在 相当不同的水平。我们假设支配MM的神经元具有不同的神经元类型- 机械刺激依赖性反应和TMDM驱动的可塑性。全细胞膜片钳 电生理学将用于研究不同TG神经元组中的机械门控电流特性 在疼痛开始时支配未处理和TMDM小鼠中的MM。最后，使用体内成像，调节 将根据TMDM状况评估不同的机械方式。这项提案的结果将有一个 通过概述新的治疗策略和预防和治疗的候选目标， 咀嚼肌痛的症状

Project Summary/Abstract Temporomandibular disorders affecting the muscles of mastication (TMDM) are the most prevalent group of chronic orofacial pain conditions. TMDM chronic pain arising from the masseter muscle (MM) is common. My long-term goals are to elucidate the underlying mechanisms controlling the development of TMDM chronicity and to understand the function and TMDM-induced plasticity of neurons innervating the MM. I recently demonstrated that the MM of mice and primates is predominantly innervated by myelinated A-fibers with unique electrophysiological characteristics and receptor compositions. To further unravel the identity of these neurons we performed single-cell RNA sequencing and have identified unique types of neurons that innervate the MM. Selective markers can be used for specific manipulation of activities for these neuronal clusters. The main objective of this proposal is to define the contribution of MM innervating TG neuronal groups in the progress of TMDM chronicity. The central hypothesis of this proposal is that neurons innervating the MM have specialized neuron type-dependent distinct contributions in the development of TMDM chronicity and undergo unique plasticity of mechano-gated responses during TMDM. To test this hypothesis, our newly developed clinically relevant model of chronic masseteric muscle pain (myalgia) in mice will be employed. Aim 1 will define the contribution of different types of neurons innervating the MM in the development of TMDM by measuring mechanical hypersensitivity using grimace scores, von Frey, conditioned place avoidance, and bite force. To do this, we will exploit the availability of transgenic mouse lines and our single-cell data for manipulation of neuronal activities for specific groups of TG neurons innervating MM. Designer Receptors Exclusively Activated by Designer Drugs (DREADD) will be used to inhibit neuronal activities. Aim 2 will examine the impact of TMDM on mechano-gated responses in neuronal groups innervating the MM. Our single-cell RNA sequencing data indicates that neuronal groups innervating MM all express the mechanically gated PIEZO-2 channel but at considerably different levels. We hypothesize that neurons innervating the MM have distinct neuron type- dependent responses to mechanical stimuli, and TMDM-driven plasticity. Whole-cell patch-clamp electrophysiology will be used to investigate mechano-gated current properties in different TG neuronal groups innervating MM in naïve and TMDM mice at the initiation of pain. Finally, using in vivo imaging, regulation of different mechanical modalities by TMDM condition will be assessed. The results from this proposal will have a positive impact by outlining novel therapeutic strategies and candidate targets for the prevention and treatment of debilitating masticatory myalgia.