Activity-dependent conduction latency changes in A beta fibers of neuropathic rats

Activity-dependent changes of the conduction latency of single A beta fibers of primary afferent neurons were characterized in both neuropathic (L4 and L6 ligated) and normal rats. Activity-dependent increases in conduction latency of dorsal root fibers in neuropathic rats were significantly stronger than those in normal rats. Different profiles of activity dependence were also observed between injured and adjacent intact dorsal root fibers of neuropathic rats. However, activity-dependent latency changes in sciatic nerves distal to the dorsal root ganglion were not different between neuropathic and normal rats. These results suggest that partial nerve injury induces activity-dependent excitability changes in the dorsal root fibers of neuropathic rat and that these changes may be responsible for the altered sensory processing such as those seen in allodynia.