Nociceptive Mechanisms Underlying Sickle Cell Pain

项目摘要/摘要： 镰状细胞病伴随着难以治疗的慢性和严重的阵发性疼痛，以及 深刻地侵蚀了那些遭受这种疾病之苦的人的生活质量。尽管我们详细了解了 镰刀状血红蛋白的遗传学、分子生物学和生化研究--深痛的发病机制 在镰状细胞病中观察到的症状仍然不完全清楚，可能涉及复杂和 在外周和中枢神经系统中都出现不同的步态。这项提案的目标是 是阐明镰状细胞病导致疼痛的机制，重点是外周机制 在初级传入神经末梢。使用严重镰状细胞疾病的小鼠模型，伯克利镰刀 小鼠，我们证明这些小鼠对机械、热和冷的外围设备表现出显著的过敏性。 刺激物。此外，低氧诱导的急性镰状反应特别加剧了正在进行的机械性 镰状细胞小鼠的超敏反应。一致认为，来自皮肤神经制剂的梳理纤维记录来自 这些小鼠表明，有髓A纤维和无髓C纤维伤害性感受器都对 机械刺激。这些发现与机械过敏和疼痛的患者报告的 镰状细胞病。因此，这些镰状细胞小鼠代表了一种新的长期慢性疼痛模型。 与人类疾病密切相关的过敏症。根据这些发现和我们的 在其他疼痛模型中观察到感觉可塑性，我们假设初级传入的敏化 终末参与了镰状细胞疼痛，这种敏化是通过增强的功能介导的。 瞬时受体电位离子通道。因此，这个项目的具体目标是：1)描述 镰状细胞小鼠初级传入纤维对机械、冷热刺激的敏化状态 疾病。2)确定瞬时受体电位(Trp)离子通道TRPA1和 TRPV1对镰状细胞行为超敏反应和初级传入纤维的敏化作用 疾病。3)研究急性血管闭塞对镰刀鼠机械超敏反应的调节作用。我们 将使用体外和体内电生理记录来表征药物的敏化状态 伯克利镰状细胞小鼠的初级传入纤维。接下来，我们将利用两种遗传(Trp通道缺失)小鼠 引起镰状细胞病)和药理方法(选择性色氨酸通道拮抗剂) 确定特定色氨酸家族离子通道在镰状细胞相关初级传入敏化中的作用 以及疼痛行为。最后，我们将通过血管闭塞的实验模型来诱导急性镰状危机 研究血管闭塞如何调节镰刀鼠的机械超敏反应。这些相互关联的特定 AIMS提供了一个多方面的、协调的和密切关注的方法，将澄清初级教育的作用 在镰状细胞诱导的复杂环境中，传入神经元在疼痛综合征发展中的作用 血管和器官病理，以及提供对靶向色氨酸受体拮抗剂的潜在价值的洞察 治疗镰状细胞疼痛的方法。

Project Summary/Abstract: Sickle cell disease is accompanied by both chronic and severe episodic pain that is difficult to treat, and profoundly erodes the quality of life of those who suffer from it. Despite a detailed understanding of the genetics, molecular biology and biochemistry of sickle hemoglobin, the pathogenesis of the profound pain syndromes observed in sickle cell disease remain incompletely understood and likely involve complex and heterogeneous steps occurring in both the peripheral and central nervous systems. The goal of this proposal is to elucidate the mechanisms by which sickle cell disease results in pain, focusing on peripheral mechanisms in primary afferent nerve terminals. Using a murine model of severe sickle cell disease, the Berkeley Sickle Mice, we demonstrate that these mice exhibit marked hypersensitivity to mechanical, heat and cold peripheral stimuli. Furthermore, induction of acute sickling with hypoxia specifically exacerbates the ongoing mechanical hypersensitivity in sickle cell mice. In agreement, teased fiber recordings from skin-nerve preparations from these mice indicate that both myelinated A¿ fiber and unmyelinated C fiber nociceptors are sensitized to mechanical stimuli. These findings parallel the mechanical hypersensitivity and pain reported by patients with sickle cell disease. Thus, these sickle cell mice represent a novel model of long-lasting chronic pain hypersensitivity that is closely associated with a human disease. On the basis of these findings and our observations with sensory plasticity in other pain models, we hypothesize that sensitization of primary afferent terminals contributes to sickle cell pain and that this sensitization is mediated by increased function of Transient Receptor Potential ion channels. Therefore, the Specific Aims for this project are to 1) Characterize the sensitization state of primary afferent fibers to mechanical, heat and cold stimuli in mice with sickle cell disease. 2) Determine the contribution of the Transient Receptor Potential (TRP) Ion Channels TRPA1 and TRPV1 to both the behavioral hypersensitivity and the sensitization of primary afferent fibers in sickle cell disease. 3) Characterize how acute vaso-occlusion modulates mechanical hypersensitivity in sickle mice. We will use both ex vivo and in vivo electrophysiological recordings to characterize the sensitization state of primary afferent fibers in Berkeley sickle cell mice. Next, we will utilize both genetic (TRP channel null mice induced with sickle cell disease) and pharmacologic approaches (selective TRP channel antagonists) to determine the role of specific TRP-family ion channels in sickle cell-associated primary afferent sensitization and pain behavior. Finally, we will induce acute sickling crises by an experimental model of vaso-occlusion to study how vaso-occlusion modulates mechanical hypersensitivity in sickle mice. These interrelated Specific Aims provide a multifaceted, coordinated and tightly focused approach that will clarify the role of primary afferent neurons in the development of pain syndromes within the complex setting of sickle cell-induced vascular and organ pathologies, as well as provide insight into the potential value of targeted TRP antagonist therapies for sickle cell pain.