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 inflammato...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 naive 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 naive 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.展开更多
基金supported by grants from the National Natural Science Foundation of China(31720103908,31530028,and 81821092)the National Basic Research Development Program of the Ministry of Science and Technology of China(2017YFA0701300).
文摘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 naive 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 naive 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.
