McDougall Jason J, Andruski Benjamin, Schuelert Niklas, Hallgrímsson Benedikt, Matyas John R
Department of Physiology & Biophysics, University of Calgary, 3330, Hospital Drive NW, Calgary, AB, Canada T2N 4N1.
Pain. 2009 Feb;141(3):222-232. doi: 10.1016/j.pain.2008.10.013. Epub 2008 Dec 9.
Osteoarthritis (OA) is a debilitating and painful disease, the incidence of which increases with advancing age. One of the confounding aspects of OA is that there is a disconnect between the severity of joint degeneration and the intensity of pain reported. This study examined the relationship between age, joint nociception, and joint pathology in an animal model of naturally occurring OA. Dunkin Hartley guinea pigs were grouped according to age: young (2-5 months) and senescent (17-37 months). Joint nociception was objectively measured in these animals by recording electrophysiologically from knee joint primary afferents in response to non-noxious and noxious movements of the knee. Joint pathology in the same knees was then determined by histomorphology and micro-computerized tomography (micro-CT). A principal components analysis was carried out on the data to determine if any correlation exists between each of the measured variables. In aged guinea pigs, 33% of joint mechanosensory nerves were spontaneously active, whereas young animals showed no such neural activity at rest. The frequency of afferent firing evoked by noxious movements was greater in old guinea pigs. Micro-CT and histopathological determination of OA positively correlated with age; however, there was no significant correlation between the severity of joint degeneration and nociception. In the Dunkin Hartley model of inveterate OA, the level of joint pathology correlates well with increasing age. This study also provides the first objective evidence that there is no correlation between joint nociception and articular damage, thereby corroborating the clinical observation that pain is a poor predictor of OA severity.
骨关节炎（OA）是一种使人衰弱且疼痛的疾病，其发病率随年龄增长而增加。OA令人困惑的一个方面在于，关节退变的严重程度与所报告的疼痛强度之间存在脱节。本研究在自然发生OA的动物模型中，考察了年龄、关节伤害感受与关节病理之间的关系。将Dunkin Hartley豚鼠按年龄分组：年轻组（2 - 5个月）和老年组（17 - 37个月）。通过对膝关节初级传入神经进行电生理记录，以响应膝关节的非伤害性和伤害性运动，从而客观测量这些动物的关节伤害感受。然后通过组织形态学和微计算机断层扫描（micro-CT）确定同一膝关节的关节病理。对数据进行主成分分析，以确定各测量变量之间是否存在任何相关性。在老年豚鼠中，33%的关节机械感觉神经自发活动，而年轻动物在静息时未表现出此类神经活动。老年豚鼠中由伤害性运动诱发的传入放电频率更高。OA的micro-CT和组织病理学测定与年龄呈正相关；然而，关节退变的严重程度与伤害感受之间无显著相关性。在Dunkin Hartley慢性OA模型中，关节病理水平与年龄增长密切相关。本研究还提供了首个客观证据，即关节伤害感受与关节损伤之间不存在相关性，从而证实了疼痛并非OA严重程度良好预测指标的临床观察结果。
