Neuronal subtype-specific plasticity in the acute to chronic pain transition

描述（由申请人提供）：对疼痛的治疗不足给社会带来了巨大的负担，部分原因是对从急性疼痛到慢性疼痛过渡的生物学事件的理解有限。更好地理解这种转变的障碍包括无法选择性和有效地可视化或操纵特定的感觉神经元群，以及在细胞水平上监测伤害感受器功能的现有方法的吞吐量非常低。在这项合作提案中，我们将一位发育神经生物学家和几位疼痛生物学家联合起来，共同克服这两个障碍。利用新开发的分子遗传学策略，我们将选择性地标记小鼠低阈值机械感受（LTMR）神经元的四个主要亚群，以及表达肽能和mrgprd的非肽能伤害感受器。该技术将与小鼠外周感觉神经元中基因编码钙指示剂GCAMP3的选择性表达相结合，以实现皮肤和DRG神经元活动的直接可视化。在我们的前两个目标中，这些工具将使我们能够有效地和高时空分辨率地监测在神经性疼痛发展过程中明确定义的伤害感受器和LTMR群体的解剖和功能变化。这些变化将与相应的行为变化相关联，使用经典的和新开发的热和机械灵敏度分析来监测。在Aim 3中，我们将选择性切除两个LTMR人群，这两个人群是疼痛的候选参与者，并定义他们各自对神经性机械超敏反应的建立、维持和表现的贡献。总之，这些研究将为我们提供与慢性疼痛过渡相关的动态过程的前所未有的观点，并为改进镇痛疗法的发展确定细胞靶点。

DESCRIPTION (provided by applicant): Inadequate treatment of pain imposes an enormous burden on society, and is due, in part, to a limited understanding of biological events that underlie the transition from acute to chronic pain. Barriers to a better understanding of this transition have included an inability to selectively and efficiently visualize or manipulate specifc sensory neuron populations and the very low throughput of available methods to monitor nociceptor function at the cellular level. In this collaborative proposal, we have teamed together a developmental neurobiologist and several pain biologists to synergistically overcome both of these barriers. Using newly- developed molecular-genetic strategies, we will selectively label each of the four major subpopulations of low- threshold mechanoreceptive (LTMR) neurons, as well as peptidergic and MrgprD-expressing nonpeptidergic nociceptors, in mice. This technology will be combined with selective expression of the genetically encoded calcium indicator, GCAMP3, in mouse peripheral sensory neurons to permit direct visualization of neuronal activity in the skin and DRG. In our first two aims, these tools will allow us to efficiently and with high spatiotemporal resolution monitor changes in the anatomy and function of unambiguously defined nociceptor and LTMR populations during the development of neuropathic pain. These changes will be correlated with corresponding behavioral changes, monitored using classical and newly developed assays of thermal and mechanical sensitivity. In Aim 3, we will selectively ablate two LTMR populations that are candidate participants in pain and define their respective contributions to the establishment, maintenance, and manifestation of neuropathic mechanical hypersensitivity. Together, these studies will provide us with an unprecedented view of the dynamic processes associated with the transition to chronic pain and define cellular targets for the development of improved analgesic therapies.