The role of botulinum toxin type A related axon transport in neuropathic pain induced by chronic constriction injury.

[BACKGROUND] The mechanism of peripheral axon transport in neuropathic pain is still unclear. Chemokine ligand 13 (CXCL13) and its receptor (C-X-C chemokine receptor type 5, CXCR5) as well as GABA transporter 1 (GAT-1) play an important role in the development of pain. The aim of this study was to explore the axonal transport of CXCL13/CXCR5 and GAT-1 with the aid of the analgesic effect of botulinum toxin type A (BTX-A) in rats.

[METHODS] Chronic constriction injury (CCI) rat models were established. BTX-A was administered to rats through subcutaneous injection in the hind paw. The pain behaviors in CCI rats were measured by paw withdrawal threshold and paw withdrawal latencies. The levels of CXCL13/CXCR5 and GAT-1 were measured by western blots.

[RESULTS] The subcutaneous injection of BTX-A relieved the mechanical allodynia and heat hyperalgesia induced by CCI surgery and reversed the overexpression of CXCL13/CXCR5 and GAT-1 in the spinal cord, dorsal root ganglia (DRG), sciatic nerve, and plantar skin in CCI rats. After 10 mmol/L colchicine blocked the axon transport of sciatic nerve, the inhibitory effect of BTX-A disappeared, and the levels of CXCL13/CXCR5 and GAT-1 in the spinal cord and DRG were reduced in CCI rats.

[CONCLUSIONS] BTX-A regulated the levels of CXCL13/CXCR5 and GAT-1 in the spine and DRG through axonal transport. Chemokines (such as CXCL13) may be transported from the injury site to the spine or DRG through axonal transport. Axon molecular transport may be a target to enhance pain management in neuropathic pain.