ACTIONS OF PROINFLAMMATORY CYTOKINES ON SENSORY NEURONS

描述（申请人摘要）：越来越多的证据表明，免疫系统的各种成分的激活有助于慢性疼痛和炎症。许多促炎细胞因子，如肿瘤坏死因子α (tnf - α)、白细胞介素1- β (il -1 β)和白细胞介素6 （IL-6）在创伤部位被合成和释放，并在疼痛动物模型中产生痛觉过敏。细胞因子诱导的痛觉增强的一种机制可能涉及它们对伤害感觉神经元的直接作用，以增强其兴奋性和/或使其对物理或化学刺激敏感。尽管有大量证据表明tnf - α、il -1 β和IL-6产生痛觉过敏和炎症，但关于它们调节调节感觉神经元功能的细胞内信号通路的能力的信息很少。这一提议的假设是，促炎细胞因子直接作用于感觉神经元，增强它们的兴奋性，使这些细胞对有害的机械和化学刺激敏感，反过来，增加这些神经元神经活性物质的释放。拟议的研究将利用两种方法：膜片钳电生理学来评估细胞因子诱导的大鼠培养感觉神经元膜兴奋性的改变，以及培养和体外制备大鼠脊髓切片中分离感觉神经元神经肽释放的生化测量。本研究的目的是：1)确定急性或慢性暴露于tnf - α、il -1 β或1L-6是否会改变膜的兴奋性和/或使分离的感觉神经元对电或化学刺激敏感；2)确定这些促炎细胞因子是否会刺激和/或使培养的大鼠感觉神经元或脊髓切片中SP和CGRP的释放敏感；3)确定促炎细胞因子对感觉神经元鞘脂第二信使和二酰基甘油的影响，建立第二信使系统的变化与细胞因子诱导的兴奋性和肽释放改变之间的因果关系。总的来说，从这些研究中获得的知识对于理解慢性疼痛的病因至关重要，并最终有助于设计缓解疼痛的干预措施。这项工作的结果可以增加对神经系统和免疫系统之间相互作用的细胞机制的理解，从而适用于神经生物学的其他领域。

DESCRIPTION (applicant's abstract): Increasing evidence suggests that activation of various components of the immune system contribute to chronic pain and inflammation. A number of pro-inflammatory cytokines such as tumor necrosis factor alpha (TNF-alpha), interleukin 1-beta (IL-1beta), and interleukin-6 (IL-6) are synthesized and released at sites of trauma and produce hyperalgesia in animal models of pain. One mechanism for cytokine-induced augmentation of pain perception could involve their direct actions on nociceptive sensory neurons to enhance excitability and/or sensitize them to physical or chemical stimuli. Despite abundant evidence that TNF-alpha, IL-1beta, and IL-6 produce hyperalgesia and inflammation, there is little information regarding their capacity to modulate intracellular signaling pathways that regulate sensory neuron function. The hypothesis of this proposal is that pro-inflammatory cytokines act directly on sensory neurons to enhance their excitability and sensitize these cells to noxious mechanical and chemical stimuli and, in turn, augment the release of neuroactive substances from these neurons. The proposed studies will utilize two approaches: patch-clamp electrophysiology to assess cytokine-induced alterations in membrane excitability in rat sensory neurons grown in culture and biochemical measurements of neuropeptide release in isolated sensory neurons grown in culture and an in vitro preparation of rat spinal cord slices. The aims of this proposal are: 1) to determine whether acute or chronic exposure to TNF-alpha, IL-1beta, or 1L-6 alters membrane excitability and/or sensitizes isolated sensory neurons to electrical or chemical stimuli, 2) to determine whether these pro-inflammatory cytokines stimulate and/or sensitize the release of SP and CGRP from rat sensory neurons grown in culture or from rat spinal cord slices; and 3) to determine the effects of pro-inflammatory cytokines on sphingolipid second messengers and diacylglycerol in sensory neurons and to establish causal relationships between changes in second messenger systems and cytokine-induced alterations in excitability and peptide release. Overall, the knowledge gained from these studies is critical for understanding the etiology of chronic pain and could eventually aid in designing interventions to alleviate the pain. The results of this work can increase the understanding of the cellular mechanisms mediating the interaction between the nervous system and the immune system and thus be applicable to other areas of neurobiology.