Molecular genetic dissection of the spinal microcircuits of wind-up

慢性疼痛是一种使人衰弱的疾病，影响四分之一的美国人， 需要安全有效的治疗。慢性疼痛患者的疼痛感觉增强， 当无害的刺激出现时会感到疼痛。然而，这种放大的神经基础是 不太了解。在这里，我们建议调查的神经回路基础上发条，一种生理类型的 中枢兴奋过度也可能导致持续性疼痛。我们提议的研究将开始， 确定参与这种放大的特定脊髓回路，并调查这些微回路是否 在受伤的情况下改变。这些知识可能阐明治疗疼痛的新治疗靶点， 这也是我们项目长期研究的目标。在第一个目标中，我们将使用我们的小说 皮肤/神经/DRG/脊髓制备结合光遗传学方法来检查 选择脊髓投射神经元中记录的皮肤感觉输入的缠绕中的细胞类型。这些研究 将通过光遗传学刺激研究皮肤感觉神经元的特定亚群在发条中的作用 它们在幼稚小鼠和神经损伤后的皮肤投射。我们还将利用光遗传学 激活或抑制遗传定义的兴奋性（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，以确定它们在该过程中的作用。在第二个目标中， 检查潜在的神经网络和/或突触机制的感觉输入的发条。在 特别是，我们将测试的作用，持续的，回荡的电流在清盘。此外，调查哪些 介质引起缓慢的去极化电流，这是经常观察到的发条，并确定这是否 起到了促进作用。在第三个目标中，我们将使用一个新的行为模型的清盘使用时间 皮肤感觉输入的总和。具体来说，我们已经开发了一个时间行为模型， 在小鼠中使用相同的光遗传学刺激进行求和，我们以前用于诱导小鼠中的缠绕。 第一目标。这将使我们能够，第一次，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感受的量度。完成本申请书所建议的研究， 提供了新的见解脊髓电路的感觉信息的处理，以及如何这些 这些过程在神经损伤后会发生改变。重要的是，可以为开发 药物治疗这些新的疗法可以提供改善的治疗，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.