Elsevier

The Journal of Pain

Volume 12, Issue 8, August 2011, Pages 868-874
The Journal of Pain

Original Report
Conditioned Place Preference Reveals Tonic Pain in an Animal Model of Central Pain

https://doi.org/10.1016/j.jpain.2011.01.010Get rights and content
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Abstract

A limitation of animal models of central pain is their inability to recapitulate all clinical characteristics of the human condition. Specifically, many animal models rely on reflexive measures of hypersensitivity and ignore, or cannot assess, spontaneous pain, the hallmark characteristic of central pain in humans. Here, we adopt a conditioned place preference paradigm to test if animals with lesions in the anterolateral quadrant of the spinal cord develop signs consistent with spontaneous pain. This paradigm relies on the fact that pain relief is rewarding to animals, and has been used previously to show that animals with peripheral nerve injury develop tonic pain. With the use of 2 analgesic treatments commonly used to treat patients with central pain (clonidine infusion and motor cortex stimulation), we demonstrate that analgesic treatments are rewarding to animals with spinal cord lesions but not sham-operated controls. These findings are consistent with the conclusion that animals with spinal cord injury suffer from tonic pain.

Perspective

The hallmark characteristic of central pain in humans is spontaneous pain. Animal models of central pain rely on reflexive measures of hypersensitivity and do not assess spontaneous pain. Demonstrating that animals with spinal cord injury suffer from tonic pain is important to study the etiology of central pain.

Key words

Spontaneous pain
motor cortex stimulation
posterior thalamus
rat
clonidine

Cited by (0)

Supported by National Institute of Neurological Disorders and Stroke Fellowships F32NS-064775 to R.L.Q. and F31NS-070458 to J.M.L., and Research Grants R01-051799 to A.K. and R01-NS069568 to R.M. Support was also provided by the Christopher and Dana Reeve Spinal Cord Research Foundation (A.K.) and the Department of Defense (SC090126 to R.M.).

The authors of this paper have no financial or other conflicts of interest to declare.

Leyla Davoody and Raimi L. Quiton contributed equally to this work.