Molecular genetic dissection of the spinal microcircuits of wind-up

慢性疼痛是一种使人衰弱的疾病，影响着四分之一的美国人，对此有一个紧迫的解决方案 需要安全、有效的治疗。慢性疼痛患者的疼痛感增强，并且经常 当出现无害的刺激时会感到疼痛。然而，这种放大的神经基础是 不太了解。在这里，我们建议研究结束的神经回路基础，结束是一种生理类型 中枢过度兴奋也可能导致持续性疼痛。我们提议的研究将开始 识别参与这种放大的特定脊髓电路，并研究这些微电路是否 受伤情况发生改变。这些知识可能会阐明治疗疼痛的新治疗靶点， 这是我们项目研究的长期目标。在第一个目标中，我们将使用我们的小说 皮肤/神经/DRG/脊髓准备结合光遗传学方法来检查 选择脊髓投射神经元记录的皮肤感觉输入的结束中的细胞类型。这些研究 将通过光遗传学刺激检查皮肤感觉神经元特定亚群在结束中的作用 他们在幼稚小鼠和神经损伤后的皮肤投射。我们还将采用光遗传学 激活或抑制基因定义的兴奋性（神经降压素（Nt）-cre）和 抑制性 (nNos-creER) 脊髓中间神经元以确定它们在此过程中的作用。在第二个目标中，我们将 检查感觉输入结束时潜在的神经网络和/或突触机制。在 特别是，我们将测试持续的回响电流在卷绕中的作用。此外，调查哪些 介体会引起缓慢的去极化电流，这种电流经常在饱和时观察到，并确定这是否 发挥着贡献作用。在第三个目标中，我们将使用一种新颖的基于时间的结束行为模型 皮肤感觉输入的总和。具体来说，我们开发了一种时间行为模型 使用我们之前用于诱导结束的相同光遗传学刺激对小鼠进行求和 第一个目标。这将使我们第一次能够在生理学之间建立直接的关联。 现象（结束）和对疼痛感知的行为反应（时间总和），使用 地方厌恶作为小鼠伤害感受的衡量标准。完成本申请中提出的研究将 提供了对感觉信息处理背后的脊髓回路的新见解，以及这些神经回路如何 神经损伤后过程发生改变。重要的是可以为发展提供潜在目标 药物治疗。这些新疗法可以提供改善的治疗方法，以缓解 慢性神经性疼痛的不良症状。

Chronic pain is a debilitating condition that affects one in four Americans, and for which there is a pressing need for safe, effective treatments. Chronic pain patients experience enhanced pain sensations and often experience pain when innocuous stimuli are presented. However, the neural basis for this amplification is poorly understood. Here, we propose to investigate the neural circuit basis for wind-up, a physiological type of central hyperexcitability that may also contribute to persistent pain. The studies we are proposing will begin to identify specific spinal circuitry involved in this amplification, and investigate whether these microcircuits are altered in conditions of injury. This knowledge may elucidate new therapeutic targets for the treatment of pain, which is the long-term goal of research of our program. In the first aim, we will use our novel skin/nerve/DRG/spinal cord preparation combined with optogenetic approaches to examine the involvement of select cell types in wind-up of cutaneous sensory inputs recorded in spinal projection neurons. These studies will examine the roles of specific subsets of cutaneous sensory neurons in wind-up by optogenetic stimulation of their cutaneous projections both in naïve mice and following nerve injury. We will also employ optogenetic strategies to activate or inhibit specific subsets of genetically defined excitatory (neurotensin (Nt)-cre) and inhibitory (nNos-creER) spinal interneurons to determine their roles in this process. In the second aim we will examine potential neural network and/or synaptic mechanisms underlying the wind-up of sensory inputs. In particular, we will test the role of persistent, reverberating currents in wind-up. In addition, investigate which mediators cause the slow depolarizing current that is often observed with wind-up, and determine whether this plays a contributing role. In the third aim, we will use a novel behavioral model of wind-up using temporal summation of cutaneous sensory inputs. Specifically, we have developed a behavioral model of temporal summation in mice using the same optogenetic stimulation that we previously used to induce wind-up in the first aim. This will allow us, for the first time, to make a direct correlation between the physiological phenomenon (wind-up) and a behavioral response to the perception of pain (temporal summation), using place-aversion as a measure of nociception in mice. Completion of the studies proposed in this application will provide new insights into spinal circuitry underlying the processing of sensory information, and how these processes are altered following nerve injury. Importantly could provide potential targets for the development of pharmaceutical therapies. These new therapies could provide for improved treatments for the alleviation of the adverse symptoms of chronic neuropathic pain.