Expectancy Effects on Conditioned Pain Modulation Are Not Influenced by Naloxone or Morphine.
Expectancy Effects on Conditioned Pain Modulation Are Not Influenced by Naloxone or Morphine.
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DOI：
10.1007/s12160-016-9775-y
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发表时间：
2016-08
期刊：
影响因子：
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通讯作者：
Bruehl S
中科院分区：
文献类型：
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作者：
France CR;Burns JW;Gupta RK;Buvanendran A;Chont M;Schuster E;Orlowska D;Bruehl S
最近的研究表明，参与者的期望影响疼痛评级在条件性疼痛调制测试。本研究扩展了这项工作，通过检查有和没有慢性背痛的个体在服用安慰剂、纳洛酮或吗啡后的预期效应。为了确定个体差异的影响，在前臂缺血性疼痛刺激之前，期间和之后获得的热疼痛评级的变化预期。患有慢性腰痛的参与者（n=88）和健康对照者（n=100）对热痛体验进行了评级（即，“测试刺激”）在暴露于缺血性疼痛之前、期间和之后（即，“条件刺激”）。在测试之前，参与者表明他们是否预期他们的热痛会增加，减少或在缺血性疼痛期间保持不变。分析预期（疼痛增加、减少或无变化）、药物（安慰剂、纳洛酮或吗啡）和组（背痛，健康）对热痛变化的影响，发现预期的主效应显著（p = 0.001），但无其他显著主效应或相互作用。随访分析显示，与预期无变化（p = 0.004）或疼痛增加（p = 0.001）的人相比，预期缺血期间疼痛较轻的人报告热痛显著减少。目前的研究结果证实，预期是一个重要的贡献者条件性疼痛调制效果，因此，显着的谨慎是必要的解释时，没有考虑到这种个体差异的结果。阿片机制似乎并不参与这些预期效应。
Recent studies suggest that participant expectations influence pain ratings during conditioned pain modulation testing. The present study extends this work by examining expectancy effects among individuals with and without chronic back pain after administration of placebo, naloxone, or morphine. To identify the influence of individual differences in expectancy on changes in heat pain ratings obtained before, during, and after a forearm ischemic pain stimulus. Participants with chronic low back pain (n=88) and healthy controls (n=100) rated heat pain experience (i.e., “test stimulus”) before, during, and after exposure to ischemic pain (i.e., “conditioning stimulus”). Prior to testing, participants indicated whether they anticipated that their heat pain would increase, decrease, or remain unchanged during ischemic pain. Analysis of the effects of Expectancy (pain increase, decrease, or no change), Drug (placebo, naloxone, or morphine), and Group (back pain, healthy) on changes in heat pain revealed a significant main effect of Expectancy (p = 0.001), but no other significant main effects or interactions. Follow-up analyses revealed that individuals who expected lower pain during ischemia reported significantly larger decreases in heat pain as compared to those who expected either no change (p = 0.004) or increased pain (p = 0.001). The present findings confirm that expectancy is an important contributor to conditioned pain modulation effects, and therefore significant caution is needed when interpreting findings that do not account for this individual difference. Opioid mechanisms do not appear to be involved in these expectancy effects.