Department of Biomedical Engineering, Science, and Health Systems, Drexel University, Philadelphia, PA, USA.
Department of Biomedical Engineering, University of California-Davis, Davis, CA, USA.
Eur J Pain. 2021 Apr;25(4):801-816. doi: 10.1002/ejp.1711. Epub 2021 Jan 25.
The rat mid-thoracic contusion model has been used to study at-level tactile allodynia, a common type of pain that develops after spinal cord injury (SCI). An important advantage of this model is that not all animals develop hypersensitivity. Therefore, it can be used to examine mechanisms that are strictly related to the development of pain-like behaviour separately from mechanisms related to the injury itself. However, how to separate animals that develop hypersensitivity from those that do not is unclear.
The aims of the current study were to identify where hypersensitivity and spasticity develop and use this information to identify metrics to separate animals that develop hypersensitivity from those that do not to study differences in their behaviour. To accomplish these aims, a grid was used to localize hypersensitivity on the dorsal trunk relative to thoracic dermatomes and supraspinal responses to tactile stimulation were tallied. These supraspinal responses were used to develop a hypersensitivity score to separate animals that develop hypersensitivity, or pain-like response to nonpainful stimuli.
Similar to humans, the development of hypersensitivity could occur with the development of spasticity or hyperreflexia. Moreover, the time course and prevalence of hypersensitivity phenotypes (at-, above-, or below level) produced by this model were similar to that observed in humans with SCI.
However, the amount of spared spinal matter in the cord did not explain the development of hypersensitivity, as previously reported. This approach can be used to study the mechanisms underlying the development of hypersensitivity separately from mechanisms related to injury alone.
大鼠胸段挫伤模型已被用于研究同节段触觉过敏，这是一种常见的脊髓损伤（SCI）后发生的疼痛类型。该模型的一个重要优势是并非所有动物都会产生感觉过敏。因此，它可以用于研究与疼痛样行为发展严格相关的机制，而与损伤本身相关的机制则分开研究。然而，如何将产生感觉过敏的动物与不产生感觉过敏的动物分开尚不清楚。
本研究的目的是确定感觉过敏和痉挛的发展部位，并利用这些信息确定指标来区分产生感觉过敏和不产生感觉过敏的动物，以研究它们行为上的差异。为了实现这些目标，使用网格来定位相对于胸皮节的背部躯干上的感觉过敏，并对触觉刺激的脊髓上反应进行计数。这些脊髓上反应被用来开发一种感觉过敏评分，以区分产生感觉过敏或对非疼痛刺激产生疼痛样反应的动物。
与人类相似，感觉过敏的发展可以与痉挛或反射亢进的发展同时发生。此外，该模型产生的感觉过敏表型（同节段、高于或低于节段）的发展时间进程和流行率与 SCI 患者观察到的相似。
然而，正如之前报道的那样，脊髓中剩余的脊髓物质的量并不能解释感觉过敏的发展。这种方法可用于研究与疼痛样行为发展相关的机制，而与损伤本身相关的机制则分开研究。
