Department of Orthopaedic Surgery, Yamaguchi University Graduate School of Medicine, 1-1-1 Minamikogushi, Ube, Yamaguchi, 755-8505, Japan.
Department of Spine and Spinal Cord Surgery, Yamaguchi Rosai Hospital, Sanyoonoda, Yamaguchi, Japan.
Biomed Eng Online. 2021 Jun 5;20(1):55. doi: 10.1186/s12938-021-00892-6.
The spinal nerve ligation (SNL) rat is well known as the most common rodent model of neuropathic pain without motor deficit. Researchers have performed analyses using only the von Frey and thermal withdrawal tests to evaluate pain intensity in the rat experimental model. However, these test are completely different from the neurological examinations performed clinically. We think that several behavioral reactions must be observed following SNL because the patients with neuropathic pain usually have impaired coordination of the motions of the right-left limbs and right-left joint motion differences. In this study, we attempted to clarify the pain behavioral reactions in SNL rat model as in patients. We used the Kinema-Tracer system for 3D kinematics gait analysis to identify new characteristic parameters of each joint movement and gait pattern.
The effect of SNL on mechanical allodynia was a 47 ± 6.1% decrease in the withdrawal threshold during 1-8 weeks post-operation. Sagittal trajectories of the hip, knee and ankle markers in SNL rats showed a large sagittal fluctuation of each joint while walking. Top minus bottom height of the left hip and knee that represents instability during walking was significantly larger in the SNL than sham rats. Both-foot contact time, which is one of the gait characteristics, was significantly longer in the SNL versus sham rats: 1.9 ± 0.15 s vs. 1.03 ± 0.15 s at 4 weeks post-operation (p = 0.003). We also examined the circular phase time to evaluate coordination of the right and left hind-limbs. The ratio of the right/left circular time was 1.0 ± 0.08 in the sham rats and 0.62 ± 0.15 in the SNL rats at 4 weeks post-operation.
We revealed new quantitative parameters in an SNL rat model that are directly relevant to the neurological symptoms in patients with neuropathic pain, in whom the von Frey and thermal withdrawal tests are not used at all clinically. This new 3D analysis system can contribute to the analysis of pain intensity of SNL rats in detail similar to human patients' reactions following neuropathic pain.
脊神经结扎（SNL）大鼠是一种常见的啮齿动物模型，用于研究无运动缺陷的神经性疼痛。研究人员仅使用 von Frey 和热回避测试来分析大鼠实验模型中的疼痛强度。然而，这些测试与临床上进行的神经学检查完全不同。我们认为，在 SNL 后必须观察到几种行为反应，因为神经性疼痛患者通常存在左右肢体运动协调受损和左右关节运动差异。在这项研究中，我们试图阐明 SNL 大鼠模型中的疼痛行为反应，就像在患者中一样。我们使用 Kinema-Tracer 系统进行 3D 运动分析，以确定每个关节运动和步态模式的新特征参数。
SNL 对机械性痛觉过敏的影响是术后 1-8 周时，退缩阈值降低了 47±6.1%。SNL 大鼠的髋关节、膝关节和踝关节标记的矢状轨迹在行走时显示出每个关节的大幅度矢状波动。代表行走时不稳定的左髋关节和膝关节的顶高与底高之差在 SNL 大鼠中明显大于假手术大鼠。双足接触时间，即步态特征之一，在 SNL 大鼠中明显长于假手术大鼠：术后 4 周时分别为 1.9±0.15 s 和 1.03±0.15 s（p=0.003）。我们还检查了圆形相位时间，以评估左右后肢的协调性。假手术大鼠的右/左圆形时间比为 1.0±0.08，而 SNL 大鼠在术后 4 周时为 0.62±0.15。
我们在 SNL 大鼠模型中发现了与神经性疼痛患者的神经症状直接相关的新定量参数，而这些参数在临床上根本不使用 von Frey 和热回避测试。这种新的 3D 分析系统可以有助于详细分析 SNL 大鼠的疼痛强度，类似于人类患者在神经性疼痛后的反应。
