PATHOPHYSIOLOGICAL TISSUE CHANGES IN RAT MODEL OF CTD

该项目将使用一种新的体内损伤模型来研究大鼠累积性创伤障碍，该模型包括在重复、姿势受限、自愿手和手腕密集运动行为的背景下对肌腱滑膜、肌肉骨骼和神经组织的损伤。本应用程序建议使用该模型来检验运动任务重复率与损伤生理和行为指标之间的暴露-反应关系。这种模型将用于未来的治疗干预和预防策略的研究，以管理累积性创伤障碍。本研究有两个具体目的：1)在大鼠重复性运动损伤模型中，研究不同暴露强度条件下，掌屈肌和腕屈肌（主要暴露部位）的局部和远处外周组织的炎症和微创伤反应。要研究的炎症变化包括炎症介质的产生，如细胞因子和COX2，以及炎症细胞（如巨噬细胞）的增加。待研究的微创伤改变包括肌腱滑膜和肌肉骨骼组织的纤维化、组成和结构改变、应激蛋白（如hsp70）的存在、髓磷脂的降解以及正中神经传导速度的降低。2)研究重复性运动损伤大鼠模型在不同暴露强度条件下的运动表现反应及其与炎症和微创伤变化的时间关系。要研究的运动性能变化包括动物在一段时间内保持目标重复率的能力、它们取回食物颗粒的成功程度、最大握力以及在取回食物颗粒过程中前肢到达和抓取的运动模式。成年Sprague-Dawley大鼠将被训练成用一只前肢通过狭窄的开口到达架子上，以两种目标速度重复取回食物颗粒：高重复率（每次15秒，n=54）和低重复率（每次45秒，n=54）。这项任务将执行2小时/天，3天/周，长达8周。将制作任务的视频记录，并使用符号系统和逐帧轨迹重建方法确定运动模式。达到重复率（RR）和颗粒回收成功将自动记录。在第3周和之后的每周，实验动物和对照动物的亚样本（n=6-9）将进行握力运动测试，然后麻醉进行正中神经NCV测试或安乐死进行肌腱滑膜、肌肉骨骼和周围神经组织的显微镜检查，包括局部和远端前肢屈肌方面，使用苏木精和免疫组织化学染色。将在实验动物和对照动物之间比较运动表现（即到达运动模式、RR、成功率和握力）、NCV和组织形态。此外，还将比较训练后和未训练前肢的NCV、握力和组织形态。这些变化与任务重复率的关系将随着时间的推移进行分析。

This project will use a novel in vivo injury model for cumulative trauma disorder in the rat that encompasses the investigation of injury of tendosynovial, musculoskeletal and nerve tissues in the context of a repetitive, posturally constrained, voluntary hand and wrist-intensive motor behavior. This application proposes the use of this model to examine the exposure-response relationship between motor task repetition rate and physiological and behavioral indicators of injury. Such a model will be used in future studies of therapeutic interventions and preventive strategies for the management of cumulative trauma disorders. The proposed study has two specific aims: 1) To investigate the inflammatory and microtraumatic responses in the peripheral tissues both local and distant to the flexors of the paw and wrist (primary exposure site) under conditions of varied exposure intensities in a rat model of repetitive motion injury. The inflammatory changes to be investigated include production of inflammatory mediators, such as cytokines and COX2, and increases in inflammatory cells, such as macrophages. The microtraumatic changes to be investigated include fibrosis, compositional and structural alterations in tendosynovial and musculoskeletal tissues, presence of stress proteins, such as hsp 70, degradation of myelin, and a decrease in nerve conduction velocity of the median nerve. 2) To investigate motor performance responses under conditions of varied exposure intensities in a rat model of repetitive motion injury and their chronological relationship to the inflammatory and microtraumatic changes observed. The motor performance changes to be investigated include the ability of animals to maintain target repetition rate over time, their success in retrieving food pellets, maximum grip force, and forelimb movement patterns of reaching and grasping during food pellet retrieval. Adult Sprague-Dawley rats will be trained to repetitively retrieve food pellets with one forelimb by reaching through a narrow opening to a shelf at two target rates: a high repetition rate (15 seconds per reach, n=54) and a low repetition rate (45 seconds per reach, n=54). This task will be performed 2 hr/day, 3 day/wk for up to 8 weeks. Video recordings of the task will be made and reach movement patterns will be determined using a notation system and frame-by-frame trajectory reconstruction method. Reach repetition rate (RR) and success of pellet retrieval will be automatically recorded. At weeks 3 and weekly thereafter, subsamples of experimental and control animals (n=6-9) will undergo motor testing for grip strength, and will then be anesthetized for median nerve NCV testing or euthanized for microscopic examination of tendosynovial, musculoskeletal and peripheral nerve tissues both local and distant to the flexor aspect of the distal forelimb using haematoxylin and immunohistochemical staining. Comparisons in motor performance (i.e. reach movement patterns, RR, success and grip strength), NCV, and tissue morphology will be made between experimental and control animals. In addition, comparisons of NCV, grip strength and tissue morphology will be made between trained and untrained forelimbs of experimental animals. The relationship of these changes to task repetition rate will be analyzed across time.