Khan Junad, Benavent Vanessa, Korczeniewska Olga A, Benoliel Rafael, Eliav Eli
Center for Orofacial Pain, Department of Diagnostic Sciences, Rutgers School of Dental Medicine, Newark, New Jersey.
Brotman Orofacial Pain Clinic at University of Maryland School of Dentistry, Baltimore, Maryland.
J Pain. 2014 Nov;15(11):1179-1189. doi: 10.1016/j.jpain.2014.08.012. Epub 2014 Sep 16.
The aim of this study was to investigate the predictive value of exercise-induced hypoalgesia (EIH) profile on pain intensity induced by nerve injury in a rat model. EIH was tested by evaluating the percentage of withdrawal responses to a train of 30 mechanical stimuli on the hind paw before and after 180 seconds of exercise on a rotating rod. The rats were grouped into low, medium, and high EIH based on their reduction in the percentage of withdrawal responses before and after exercise. Rats from each group then underwent left sciatic nerve constriction injury. Mechanical allodynia, mechanical hyperalgesia, and heat allodynia were assessed in the affected and contralateral hind paws prior to and 3 and 7 days following the procedure. The low EIH rats demonstrated increased hypersensitivity at baseline and developed significantly more severe heat allodynia, mechanical allodynia, and hyperalgesia 3 and 7 days following the injury compared to the medium and high EIH rats. Moreover, the low EIH rats developed contralateral heat allodynia following the injury. The EIH of habituated and nonhabituated rats was compared to study the role of stress on the hypoalgesic effect. No significant differences were found between the habituated and nonhabituated rats at baseline and 1 and 5 minutes after the exercise.
EIH profile was found to be predictive of pain severity following nerve injury. It may suggest that selected patients with faulty pain modulation are at risk for developing chronic pain following injury or surgical procedures. EIH may represent a preoperative means to detect this predisposition and enable proactive management.
本研究的目的是在大鼠模型中研究运动诱导性痛觉减退（EIH）特征对神经损伤所致疼痛强度的预测价值。通过评估在旋转杆上运动180秒前后后爪对30次机械刺激序列的撤回反应百分比来测试EIH。根据运动前后撤回反应百分比的降低情况，将大鼠分为低、中、高EIH组。然后，每组大鼠接受左侧坐骨神经缩窄损伤。在手术前以及手术后3天和7天，评估患侧和对侧后爪的机械性异常性疼痛、机械性痛觉过敏和热异常性疼痛。与中、高EIH大鼠相比，低EIH大鼠在基线时表现出更高的敏感性，并且在损伤后3天和7天出现明显更严重的热异常性疼痛、机械性异常性疼痛和痛觉过敏。此外，低EIH大鼠在损伤后出现对侧热异常性疼痛。比较习惯化和非习惯化大鼠的EIH，以研究应激对痛觉减退作用的影响。在基线时以及运动后1分钟和5分钟，习惯化和非习惯化大鼠之间未发现显著差异。
发现EIH特征可预测神经损伤后的疼痛严重程度。这可能表明，某些疼痛调节功能有缺陷的患者在受伤或手术后有发生慢性疼痛的风险。EIH可能是检测这种易感性并进行积极管理的术前手段。
