Understanding the spinal circuitry of cold

皮肤温度感应对于检测和避免潜在有害的环境温度至关重要， 以及体温调节。在神经性疼痛的情况下，这种机制经常出错， 表现为冷过敏，在这种情况下，正常的冷输入被认为是痛苦的冷。一个 对冷刺激如何在神经系统中编码的有限了解导致了这种虚弱的状况 管理不善。最近的研究表明，冷输入是从外周传递到中枢神经的 系统由一群表达温度敏感阳离子通道TRPM8的初级传入细胞组成。 然而，这种信息在脊髓中被处理并传递到 大脑几乎仍然是完全未知的。为了解决这一根本的知识差距，这项提议将 通过行为、电生理的组合来剖析编码冷刺激的神经回路 和形态方法。根据我们的初步研究，我们认为冷输入是从 脊髓通过神经激肽1受体(NK1R)表达的脊髓臂投射到脑 神经元。为了研究这种可能性，我们的实验室最近产生了一个NK1R-Creer等位基因，从而为我们提供了 通过遗传途径标记和操纵NK1R神经元的活动。这项提议将检验这一假设 这种冷输入通过形态上不同的NK1R神经元的子集从脊髓传递到大脑 接受来自冷感觉的突触输入(直接或间接)，TRPM8初级感觉传入。目标1将 用行为学方法研究NK1R脊髓投射神经元是否与厌恶寒冷有关。 目标2将解剖TRPM8初级传入神经元和NK1R脊髓投射神经元之间的电路 使用电生理学和光遗传学方法结合我们的体外实验对冷刺激做出反应 体感制剂。AIM 3将通过以下方式确定冷选择性脊髓投射神经元的形态 用组织学重建脊髓背角内的细胞结构。这些实验将确定 调节冷输入的基本脊椎回路，从而提供了一个研究框架 在未来的研究中，作为冷过敏基础的回路的变化。这是一个多方面的成功 研究金培训计划，包括科学和职业发展活动，将由 匹兹堡疼痛中心提供的科学专业知识、协作和教育机会 研究。

Cutaneous thermosensation is critical for detecting and avoiding potentially harmful environmental temperatures, as well as thermoregulation. This mechanism frequently goes awry under neuropathic pain conditions, manifesting as cold hypersensitivity, a condition in which normally cool input is perceived as painfully cold. A limited understanding of how cold stimuli are encoded in the nervous system has left this debilitating condition poorly managed. Recent studies suggest that cold input is conveyed from the periphery to the central nervous system by a population of primary afferents that express the temperature-sensitive cation channel TRPM8. However, the neural circuits through which this information is processed in the spinal cord and conveyed to the brain remain almost completely unknown. To address this fundamental gap in knowledge, this proposal will dissect the neural circuitry that encodes cold stimuli through a combination of behavioral, electrophysiological and morphological approaches. Based on our preliminary studies, we believe that cold input is conveyed from the spinal cord to the brain by a subset of neurokinin 1 receptor (NK1R)-expressing spinoparabrachial projection neurons. To investigate this possibility, our lab recently generated a NK1R-CreER allele, thereby providing us with genetic access to label and manipulate the activity of NK1R neurons. This proposal will test the hypothesis that cold input is conveyed from the spinal cord to the brain by a subset of morphologically distinct NK1R neurons that receive synaptic input (direct or indirect) from cold-sensing, TRPM8 primary sensory afferents. Aim 1 will investigate whether NK1R spinal projection neurons are required for aversion to cold using behavioral assays. Aim 2 will dissect the circuitry between TRPM8 primary afferents and NK1R spinal projection neurons that respond to cold stimuli using electrophysiology and optogenetic approaches in combination with our ex vivo somatosensory preparation. Aim 3 will determine the morphology of cold-selective spinal projection neurons by using histology to reconstruct cell architecture within the spinal cord dorsal horn. These experiments will establish the basic spinal circuitry that mediates cold input, thereby providing a framework from which to investigate changes in circuitry that underlie cold hypersensitivity in future studies. The success of this multifaceted fellowship training plan, which includes activities for scientific and career development, will be aided by the scientific expertise, collaboration, and educational opportunities offered by the Pittsburgh Center for Pain Research.