CC-chemokine MIP-1α in the spinal cord contributes to nerve injury-induced neuropathic pain

We investigated the involvement of spinal macrophage inflammatory protein-1α (MIP-1α), an inflammatory chemokine, in partial sciatic nerve ligation (PSL)-induced neuropathic pain in mice. PSL increased MIP-1α mRNA levels as well as levels of the MIP-1α receptor, CCR1, but not CCR5 in the spinal dorsal horn. PSL-induced tactile allodynia and thermal hyperalgesia were prevented by intrathecal (i.t.) injection of a neutralizing antibody of MIP-1α (2 ng). Recombinant MIP-1α (10 pmol, i.t.) elicited long-lasting tactile allodynia and thermal hyperalgesia in naïve mice. These results suggest that peripheral nerve injury elicits the up-regulation of spinal MIP-1α and CCR1 to participate in neuropathic pain.