Department of Neurobiology, School of Basic Medical Sciences and Neuroscience Research Institute, Key Laboratory for Neuroscience, Ministry of Education of China, and National Health Commission, State key Laboratory of Natural and Biomimetic Drugs, Peking University, Beijing, 100083, China.
PKU-IDG/McGovern Institute for Brain Research, Peking University, Beijing, 100871, China.
Neurosci Bull. 2020 Feb;36(2):121-133. doi: 10.1007/s12264-019-00420-6. Epub 2019 Aug 21.
With the shifting role of placebos, there is a need to develop animal models of placebo analgesia and elucidate the mechanisms underlying the effect. In the present study, male Sprague-Dawley rats with chronic inflammatory pain caused by complete Freund's adjuvant (CFA) underwent a series of conditioning procedures, in which morphine was associated with different cues, but they failed to induce placebo analgesia. Then, conditioning with the conditioned place preference apparatus successfully induced analgesic expectancy and placebo analgesia in naïve rats but only induced analgesic expectancy and no analgesic effect in CFA rats. Subsequently, we found enhanced c-fos expression in the nucleus accumbens and reduced expression in the anterior cingulate cortex in naïve rats while c-fos expression in the anterior cingulate cortex in CFA rats was not altered. In summary, the behavioral conditioning model demonstrated the difficulty of establishing a placebo analgesia model in rats with a pathological condition.
随着安慰剂作用的转变，有必要开发安慰剂镇痛的动物模型，并阐明其作用机制。在本研究中，慢性完全弗氏佐剂（CFA）诱导的炎症痛雄性 Sprague-Dawley 大鼠接受了一系列的条件处理，其中吗啡与不同的线索相关联，但未能诱导安慰剂镇痛。随后，用条件性位置偏爱装置进行条件处理成功地诱导了未处理大鼠的镇痛预期和安慰剂镇痛，但在 CFA 大鼠中仅诱导了镇痛预期而无镇痛作用。随后，我们发现，在未处理大鼠中，伏隔核中的 c-fos 表达增强，而在前扣带回皮层中的表达降低，而在 CFA 大鼠中，前扣带回皮层中的 c-fos 表达没有改变。总之，行为条件处理模型表明，在病理条件下建立大鼠安慰剂镇痛模型具有一定的难度。
