Departments of Psychology and.
Anesthesia, Alan Edwards Centre for Research on Pain, McGill University, Montreal, QC, Canada.
Pain. 2019 Apr;160(4):784-792. doi: 10.1097/j.pain.0000000000001454.
The counterirritation phenomenon known as conditioned pain modulation, or diffuse noxious inhibitory control in animals, is of increasing interest due to its utility in predicting chronic pain and treatment response. It features considerable interindividual variability, with large subsets of pain patients and even normal volunteers exhibiting hyperalgesia rather than hypoalgesia during or immediately after receiving a conditioning stimulus. We observed that mice undergoing tonic inflammatory pain in the abdominal cavity (the conditioning stimulus) display hyperalgesia, not hypoalgesia, to noxious thermal stimulation (the test stimulus) applied to the hindpaw. In a series of parametric studies, we show that this hyperalgesia can be reliably observed using multiple conditioning stimuli (acetic acid and orofacial formalin), test stimuli (hindpaw and forepaw-withdrawal, tail-withdrawal, hot-plate, and von Frey tests) and genotypes (CD-1, DBA/2, and C57BL/6 mice and Sprague-Dawley rats). Although the magnitude of the hyperalgesia is dependent on the intensity of the conditioning stimulus, we find that the direction of effect is dependent on the effective test stimulus intensity, with lower-intensity stimuli leading to hyperalgesia and higher-intensity stimuli leading to hypoalgesia.
已知的一种反刺激现象，即条件性疼痛调制，或动物的弥散性伤害性抑制控制，由于其在预测慢性疼痛和治疗反应方面的效用而引起了越来越多的关注。它具有相当大的个体间变异性，大量的疼痛患者，甚至正常志愿者在接受条件刺激时或之后立即表现出痛觉过敏，而不是痛觉减退。我们观察到，在腹腔（条件刺激）经历持续性炎症疼痛的小鼠对施加于后爪的有害热刺激（测试刺激）表现出痛觉过敏，而不是痛觉减退。在一系列参数研究中，我们表明，使用多种条件刺激（乙酸和口腔福尔马林）、测试刺激（后爪和前爪撤回、尾巴撤回、热板和 von Frey 测试）和基因型（CD-1、DBA/2 和 C57BL/6 小鼠和 Sprague-Dawley 大鼠）可以可靠地观察到这种痛觉过敏。尽管痛觉过敏的程度取决于条件刺激的强度，但我们发现，作用方向取决于有效测试刺激的强度，低强度刺激导致痛觉过敏，高强度刺激导致痛觉减退。
