Fig. 3. Spinal CD74 was up-regulated after CCI. The expression of spinal MIF in the ipsilateral dorsal horn was up-regulated critically after CCI treatment, and this change occurred because of day 3 from the nerve injury (A and B ; n = 6 in the sham group and n = 8 in the CCI group; A : *P and #P < 0.001; B : *P < 0.05 vs. D1, #P <0.05 vs. D3 or D7, respectively; D: day). (C ) The expression of MIF receptor CD74 measured using western blotting was up-regulated in the ipsilateral spinal cord dorsal horn (n = 5 in the sham group and n = 8 in the CCI group; *P , #P , and **P all <0.001; D: day). (D ) CD74 expression detected with immunofluorescence significantly increased in the ipsilateral dorsal horn after CCI injury (a and b ; n = 6; red color: Texas Red-conjugated antibody; scale bar: 120 μm). (E ) Colocalization of MIF receptor CD74 and microglia marker CD11b, astrocyte marker GFAP, and neuron marker NeuN, and found that spinal microglial cells were the functional target of MIF in CCI-treated spinal cord (a to c , a ′ to c ′, and a" to c") (n = 4; red color: Texas Red-conjugated antibody; green color: FITC-conjugated antibody; scale bar: 40 μm). Data are shown as means ± SDs. CCI = chronic constriction sciatic nerve injury; MIF = macrophage migration inhibitory factor; FITC = fluorescein isothiocyanate; Ipsi = ipsilateral; Contra = contralateral; GFAP = glial fibrillary acidic protein; NeuN = neuronal nuclei; GAPDH = glyceraldehydes 3-phosphate dehydrogenase.