Molecular genetic dissection of the spinal microcircuits of wind-up

慢性疼痛是一种使人虚弱的疾病，影响着四分之一的美国人，对此有迫切的需求 需要安全、有效的治疗方法。慢性疼痛患者的痛感增强，通常 当出现无害的刺激时，体验疼痛。然而，这种扩增的神经基础是 人们对此知之甚少。在这里，我们建议研究发条的神经电路基础，发条是一种生理学类型的 中枢性过度兴奋也可能导致持续性疼痛。我们提议的研究将开始 确定与这种放大有关的特定脊髓回路，并调查这些微回路是否 在受伤的情况下改变的。这一知识可能阐明治疗疼痛的新的治疗目标， 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/背根神经节/脊髓准备结合光遗传学方法检查参与 在脊髓投射神经元中记录的皮肤感觉输入的缠绕中选择细胞类型。这些研究 我将研究特定的皮肤感觉神经元亚群在光遗传刺激的发条过程中的作用 它们在幼稚小鼠和神经损伤后的皮肤投射。我们还将采用光伏发电 激活或抑制基因定义的兴奋性(神经降压素(NT)-cre)的特定亚群的策略 抑制性(nNOS-Creer)脊髓中间神经元，以确定它们在这一过程中的作用。在第二个目标中，我们将 检查潜在的神经网络和/或突触机制，这些机制是感觉输入发条的基础。在……里面 特别是，我们将测试持续的混响电流在上弦中的作用。此外，还应调查 中介体导致缓慢的去极化电流，这通常是通过上发条观察到的，并确定这是否 起到了贡献的作用。在第三个目标中，我们将使用一种新的行为模型，该模型使用时间 皮肤感觉输入的总和。具体地说，我们开发了一个时态的行为模型 在小鼠身上使用相同的光遗传刺激来进行求和，我们以前使用过的刺激方法是在 第一个目标。这将使我们第一次能够在生理和心理之间建立直接的联系 现象(发条)和对疼痛感知的行为反应(时间总和)，使用 位置厌恶作为小鼠伤害性感受的衡量标准。完成本申请书中建议的研究将 提供对感官信息处理的潜在脊髓回路的新见解，以及这些 神经损伤后，突起会发生改变。重要的是可以为发展提供潜在的目标 药物疗法。这些新的疗法可以提供更好的治疗方法来缓解 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.