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的累积创伤障碍，该模型包括在重复的、后受限的、自愿的手和手腕强化运动行为的背景下调查腱滑膜、肌肉骨骼和神经组织的损伤。本申请建议使用该模型来检验运动任务重复率与损伤的生理和行为指标之间的暴露-反应关系。这一模式将用于今后对治疗干预和预防战略的研究，以管理累积创伤障碍。本研究有两个具体目的：1)研究重复运动损伤大鼠在不同暴露强度条件下，爪屈肌和腕屈肌周围组织(主要暴露部位)的炎症反应和微创反应。需要研究的炎症变化包括炎症介质的产生，如细胞因子和COX2，以及炎症细胞的增加，如巨噬细胞。需要研究的微创变化包括肌腱滑膜和肌肉骨骼组织的纤维化、成分和结构变化，存在应激蛋白，如HSP70，髓鞘降解，以及正中神经神经传导速度减慢。2)研究重复运动损伤大鼠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改变的时间关系。要研究的运动表现变化包括动物在一段时间内保持目标重复率的能力，它们在回收食物颗粒方面的成功，最大握力，以及在回收食物颗粒过程中伸手和抓取的前肢运动模式。成年SD大鼠将接受训练，通过一个狭窄的前肢以两种目标速率到达货架：高重复速率(每到达15秒，n=54)和低重复速率(每到达45秒，n=54)重复地取出食物颗粒。这项任务将执行2小时/天，3天/周，最多8周。将对任务进行视频记录，并使用记数系统和逐帧轨迹重建方法确定到达运动模式。达到重复率(RR)和取回颗粒的成功将被自动记录。在实验3周及之后的每周，实验动物和对照动物(n=6-9)的亚样将接受握力运动测试，然后麻醉进行正中神经NCV测试，或安乐死检查肌腱滑膜、肌肉骨骼和周围神经组织，用苏木素和免疫组织化学染色观察肌腱滑膜、肌肉骨骼和周围神经组织在前肢远端屈肌方面的局部和远处。实验动物和对照动物在运动性能(即REACH运动模式、RR、成功率和握力)、NCV和组织形态方面进行比较。此外，还将对经过训练和未训练的实验动物的前肢进行NCV、握力和组织形态的比较。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.