Effect of colchicine on neuropeptide Y expression in rat dorsal root ganglia and spinal cord

Neuropeptide Y (NPY) expression in the spinal cord and dorsal root ganglia (DRG) was examined after application of colchicine, an axonal transport blo cker, on the intact sciatic nerve or prior to axotomy or chronic constricti on injury (CCI). Rats that underwent topical application of colchicine on t he sciatic nerve showed decreased responsiveness to heat stimulation, ipsil aterally. CCI-induced hyperalgesia was prevented by prior application of co lchicine. However, colchicine did not block axotomy-induced NPY increase wh en applied proximally to the injury. In fact, colchicine induced the expres sion of NPY in the DRG and spinal cord in an identical manner to axotomy. T he present data indicates that the increase in NPY observed after nerve inj ury could be initiated by the suppression of retrograde transport of factor s, possibly neurotrophins, rather than by the production of an active facto r at the site of injury. (C) 1999 Elsevier Science Ireland Ltd. All rights reserved.