Figure 7.

The RvE1-ChemR23 axis is involved in HIS-induced analgesia.

(A, B) ChemR23 expression was significantly lower in the sh-ChemR23 group than in the sh-Neg control group and naïve group (n = 6 mice/group). *P < 0.05, **P < 0.01 and #P < 0.05, vs. naïve or sh-Neg control group. (C–F) The bilateral mechanical and heat pain thresholds in the sh-ChemR23 group were significantly decreased compared with those in the sh-Neg control and naïve groups (n = 7 naïve mice, n = 13 sh-Neg control mice, and n = 13 sh-ChemR23 mice (C); n = 9 naïve mice, n = 13 sh-Neg control mice, and n = 13 sh-ChemR23 mice (D); n = 6 naïve mice, n = 10 sh-Neg control mice, and n = 10 sh-ChemR23 mice (E and F)). *P < 0.05, **P < 0.01 and ***P < 0.001, vs. naïve group; ##P < 0.01 and ###P < 0.001, vs. sh-Neg control group; $$P < 0.01 and $$$P < 0.001, vs. before exercise. (G) Representative images of Iba1 (green, Alexa Fluor 488) immunofluorescence staining in the bilateral spinal dorsal horn in CPIP mice in the sh-Neg control exercise group and the sh-ChemR23 exercise group. The Iba1 fluorescence signal in CPIP sh-ChemR23 mice subjected to exercise was greater than that observed in CPIP sh-Neg control mice subjected to exercise. The righthand images (bar: 100 μm) are high magnifications of the boxes in the lefthand images (bar: 200 μm). (H, I) Iba1 fluorescence intensity and numbers of Iba1-positive microglia (n = 3 mice/group). **P < 0.01 and ****P < 0.0001, vs. sh-Neg control group. (J, K) The CPIP-induced increases in proinflammatory cytokine mRNA levels were not decreased after HIS in the sh-ChemR23 group (n = 3 mice/group). *P < 0.05, **P < 0.01 and ***P < 0.001, vs. sh-Neg control group. All data are presented as the mean ± SEM, and were analyzed by two-way analysis of variance followed by Bonferroni post hoc test (B–F) or two-tailed unpaired Student’s t-test (H-K). Detailed statistical information is shown in Additional Table 2 ^{(125.3KB, pdf)} and Additional file 1 ^{(136.8KB, pdf)} . ChemR23: Chemerin receptor 23; Contra: contralateral; CPIP sh-ChemR23: mice were injected ChemR23 shRNA-expressing lentivirus and submitted to chronic postischemia pain; CPIP sh-Neg con: mice were injected were injected nontargeting control shRNA-expressing lentivirus and submitted to chronic postischemia pain; GAPDH: glyceraldehyde-3-phosphate dehydrogenase; Iba1: ionized calcium binding adaptor molecule 1; IL: interleukin; IOD: integrated optical density; Ipsi: ipsilateral; RvE1: Resolvin E1; sh-ChemR23: mice were injected with ChemR23 shRNA-expressing lentivirus; sh-Neg con: mice were injected with nontargeting control shRNA-expressing lentivirus; TNF-α: tumor necrosis factor-α.