Mechanisms of muscle afferent sensitization after ischemia

摘要：虽然对皮肤的感觉传导机制了解很多，但相对来说 人们对肌肉的这一过程知之甚少。作为反复发生的外周损伤 缺血/再灌注(I/R)是影响美国数百万人的主要健康问题，这一差距 知识使我们无法确定肌肉疼痛或心血管改变的具体治疗方法 在缺血情况下对运动的反应。外周I/R发生在血液疾病中，如镰状细胞 疾病，以及心血管疾病，如外周血管疾病。男性和女性展示 外周减少条件下肌痛和运动加压反射的不同特征 灌流。这项研究的主要目的是确定肌肉的性别特异性分子机制。 传入敏感化可能是急性向慢性缺血性肌痛转变的基础。中的试点数据 重复性I/R损伤的小鼠模型表明，雄性动物的外周敏化受 胶质细胞源性神经营养因子家族受体-1对背根神经节基因表达的调节 (GFR1)在肌肉伤害性感受器中的表达。在女性，传入敏感化、疼痛相关行为和改变的EPR 反复I/R损伤可能受白介素1受体1(IL1r1)依赖基因的调节 表情。我们假设连续的I/R损伤的延长效应是由GDNF介导的 男性的相关外周致敏和女性的IL-1诱导致敏。目标1将决定是否 肌纤维产生胶质细胞源性神经营养因子和背根神经节上调胶质细胞生长因子受体-1，调节观察到的肌肉传入变化 男性双I/R后的反应特性、疼痛相关行为和EPR改变。我们将使用肌肉纤维 特异性GDNF消融或我们新的体内siRNA介导的单个周围神经基因的敲除 与我们的体外肌肉传入一起记录疼痛样行为和EPR的准备或分析。 AIM 2将使用类似的方法，只是我们将确定巨噬细胞是否产生IL1或DRG IL1r1的表达上调，调节了女性肌肉在连续I/R后传入或行为的新变化。 最后，Aim 3将使用体外记录和疼痛相关的行为分析来确定是否表达 富含AU的元件RNA结合蛋白1(AUF1)或ras家族成员RAN的差异调节 女性与男性之间连续I/R损伤的性别特异性影响。这些目标中的每一个都将 辅以背根神经节和肌肉基因表达的分析。这里概述的研究还将提供 肌肉神经生物学研究的新方向将远远超出电流的增量扩展 报告。结果将使我们能够识别与肌肉传入相关的独特的性别依赖机制 敏感化是I/R损伤后急性或慢性缺血性肌痛发生的基础。这可能会导致 制定更合适的治疗肌肉骨骼疼痛或与缺血相关的EPR改变的方法/ 靶向适当受体(S)、初级传入亚群(S)或周围靶组织的再灌注。

Abstract: While great deal is understood about mechanisms of sensory transduction from the skin, relatively little is known about this process from the muscles. As peripheral injuries resulting from repetitive ischemic/reperfusion (I/R) are a major health issue that affects millions of people in the United States, this gap in knowledge precludes us from identifying specific therapies for muscle pain or altered cardiovascular responses to exercise in the context of ischemia. Peripheral I/R occurs in blood disorders such as sickle cell disease, and in cardiovascular disorders such as peripheral vascular disease. Males and females display different features of myalgia and exercise pressor reflexes (EPRs) under conditions of reduced peripheral perfusion. The major goal of this study is to determine the sex specific molecular mechanisms of muscle afferent sensitization that may underlie the transition from acute to chronic ischemic myalgia. Pilot data in murine models of repetitive I/R injury suggest that peripheral sensitization in males is regulated by increased DRG gene expression that is modulated by glial cell line-derived neurotrophic factor (GDNF) family receptor 1 (GFR1) in muscle nociceptors. In females, afferent sensitization, pain-related behaviors and altered EPRs after repeated I/R injury may be regulated by increased interleukin 1 receptor type 1 (IL1r1) dependent gene expression. We hypothesize that the prolonged effects of successive I/R injuries are mediated by GDNF related peripheral sensitization in males and IL1 induced sensitization in females. Aim 1 will determine if myofiber produced GDNF and DRG upregulation of GFR1, regulate the observed changes in muscle afferent response properties, pain-related behaviors and altered EPRs after dual I/R in males. We will use muscle fiber specific GDNF ablation or our novel in vivo siRNA-mediated knockdown of genes in single peripheral nerves in conjunction with our ex vivo muscle afferent recording preparations or assays of pain-like behaviors and EPRs. Aim 2 will utilize a similar approach except we will determine if macrophage produced IL1 or DRG upregulation of IL1r1, regulate the novel changes in female muscle afferents or behaviors after successive I/R. Finally, Aim 3 will use ex vivo recording and pain-related behavioral analyses to determine if expression differences in AU-rich element RNA-binding protein 1 (AUF1) or the ras family member, RAN, modulates the sex specific effects of successive I/R injuries between females versus males. Each of these aims will be complemented by analysis of DRG and muscle gene expression. The studies outlined here will also provide a novel direction in muscle neurobiology research that will go well beyond the incremental expansion of current reports. Results will enable us to identify unique sex dependent mechanisms associated with muscle afferent sensitization that underlie acute to chronic ischemic myalgia development after I/R injury. This may lead to the formulation of more appropriate treatments for musculoskeletal pain or altered EPRs associated with ischemia/ reperfusion that target the proper receptor(s), primary afferent subpopulation(s) or peripheral target tissues.