Tonic immobility produces hyperalgesia and antagonizes morphine analgesia

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Science  17 Jul 1981:
Vol. 213, Issue 4505, pp. 353-354
DOI: 10.1126/science.7244620


Hyperalgesia was demonstrated during and immediately after termination of tonic immobility in the lizard Anolis carolinensis. Additionally, tonic immobility antagonized morphine-induced analgesia. In conjunction with other research, these data suggest that the response is accompanied by a reduced availability of serotonin, possibly at postsynaptic receptors of raphe neurons.