Opioids are powerful analgesic drugs that are used clinically to treat pain. However, chronic opioid use causes compensatory neuroadaptations that result in greater pain sensitivity during withdrawal, known as opioid withdrawal-induced hyperalgesia (OWIH). Cold nociception tests are commonly used in humans, but preclinical studies often use mechanical and heat stimuli to measure OWIH. Thus, further characterization of cold nociception stimuli is needed in preclinical models. We assessed three cold nociception tests—thermal gradient ring (5–30 °C, 5–50 °C, 15–40 °C, and 25–50 °C), dynamic cold plate (4 °C to −1 °C at −1 °C/min, −1 °C to 4 °C at +1 °C/min), and stable cold plate (10 °C, 6 °C, and 2 °C)—to measure hyperalgesia in a mouse protocol of heroin dependence. On the thermal gradient ring, mice in the heroin withdrawal group preferred warmer temperatures, and the results depended on the ring's temperature range. On the dynamic cold plate, heroin withdrawal increased the number of nociceptive responses, with a temperature ramp from 4 °C to −1 °C yielding the largest response. On the stable cold plate, heroin withdrawal increased the number of nociceptive responses, and a plate temperature of 2 °C yielded the most significant increase in responses. Among the three tests, the stable cold plate elicited the most robust change in behavior between heroin-dependent and nondependent mice and had the highest throughput. To pharmacologically characterize the stable cold plate test, we used μ-opioid and non-opioid receptor-targeting drugs that have been previously shown to reverse OWIH in mechanical and heat nociception assays. The full μ-opioid receptor agonist methadone and μ-opioid receptor partial agonist buprenorphine decreased OWIH, whereas the preferential μ-opioid receptor antagonist naltrexone increased OWIH. Two N-methyl-d-aspartate receptor antagonists (ketamine, MK-801), a corticotropin-releasing factor 1 receptor antagonist (R121919), a β₂-adrenergic receptor antagonist (butoxamine), an α₂-adrenergic receptor agonist (lofexidine), and a 5-hydroxytryptamine-3 receptor antagonist (ondansetron) had no effect on OWIH. These data demonstrate that the stable cold plate at 2 °C yields a robust, reliable, and concise measure of OWIH that is sensitive to opioid agonists.

阿片类药物是临床上用于治疗疼痛的强效镇痛药物。然而，长期使用阿片类药物会导致代偿性神经适应，导致戒断期间疼痛敏感性更高，称为阿片类药物戒断引起的痛觉过敏（OWIH）。冷伤害感受测试通常用于人类，但临床前研究经常使用机械和热刺激来测量 OWIH。因此，临床前模型需要进一步表征冷伤害感受刺激。我们评估了三种冷伤害感受测试——热梯度环（5-30°C、5-50°C、15-40°C 和 25-50°C）、动态冷板（4°C 至 -1°C，温度−1 °C/min、-1 °C 至 4 °C（+1 °C/min）和稳定冷板（10 °C、6 °C 和 2 °C）——用于测量小鼠方案中的痛觉过敏海洛因依赖。在热梯度环上，海洛因戒断组的小鼠更喜欢温暖的温度，结果取决于环的温度范围。在动态冷板上，海洛因戒断增加了伤害性反应的数量，温度从 4 °C 升至 -1 °C 会产生最大的反应。在稳定的冷板上，海洛因戒断增加了伤害性反应的数量，2°C 的板温使反应增加最显着。在这三项测试中，稳定的冷板在海洛因依赖和非海洛因依赖小鼠之间引起了最强烈的行为变化，并且具有最高的吞吐量。为了从药理学上表征稳定的冷板试验，我们使用了 μ-阿片类药物和非阿片类受体靶向药物，这些药物先前已在机械和热伤害实验中被证明可以逆转 OWIH。完全μ-阿片受体激动剂美沙酮和μ-阿片受体部分激动剂丁丙诺啡降低了OWIH，而优先μ-阿片受体拮抗剂纳曲酮则增加了OWIH。两种N-甲基-d-天冬氨酸受体拮抗剂（氯胺酮，MK-801），一种促肾上腺皮质激素释放因子 1 受体拮抗剂（R121919），一种 β2-_肾上腺素能受体拮抗剂（丁氧胺），一种 α2-_肾上腺素能受体激动剂（洛非西丁） ）和 5-羟色胺-3 受体拮抗剂（昂丹司琼）对 OWIH 没有影响。这些数据表明，2°C 下的稳定冷板可产生对阿片类激动剂敏感的 OWIH 稳健、可靠且简洁的测量结果。