C-fos expression in the spinal cord of rats exhibiting allodynia followingcontusive spinal cord injury

Contusive spinal cord injury (SCI) may result in central neuropathic pain m arked by allodynia-like features in the dermatomes close to the level of in jury. The aim of this study was to compare the laminar distribution of acti vated neurons (as determined by c-Sos immediate early gene expression) in t he spinal cord immediately above the level of a SCI in rats with or without allodynia-like features. Non-noxious mechanical stimulation was applied to half the animals in the dermatomes corresponding to the level of injury pr ior to perfusion. Stimulation resulted in a significant increase in c-fos l abelling in all laminae of the spinal dorsal horn in the segment immediatel y above the level of injury only in allodynic animals. Animals that had all odynia also demonstrated a significant increase in the level of c-fos label ling in lamina III, IV and V of the dorsal horn without stimulation. Thus, allodynia following SCI is associated with significant increases in basal a nd evoked c-fos expression ("neuronal activity") in response to non-noxious mechanical stimulation. The data also suggest that allodynia-like behaviou r following SCI cannot be accounted for solely by changes occurring at a sp inal level. (C) 1999 Elsevier Science B.V. All rights reserved.