Expression of CX3CL1 and its receptor CX3CR1 in the lumbar spinal cord. A, Double immunofluorescence staining shows that CX3CL1 is colocalized with the neuronal marker NeuN and VGCC α2/δ-1 subunits in all of the layers of the spinal dorsal horn. B, The western blot shows an increase in the level of CX3CL1 in the ipsilateral lumbar spinal dorsal horn at 4 hrs and 4 days after MA. C, Western blot analysis reveals that repeated Gab treatment significantly suppresses MA-induced upregulation of CX3CL1 in the lumbar spinal dorsal horn. D, Double immunofluorescence staining shows that CX3CR1 is colocalized with the microglial marker OX-42, but not the astrocytic marker GFAP. E, Western blot analysis reveals that repeated Gab treatment partially inhibits MA-induced upregulation of CX3CR1 in the lumbar spinal dorsal horn. * p < 0.05, ** p < 0.01 vs. control (sham MA or naïve); ++ P < 0.01 vs. MA.