Fig. 4

Red nucleus IL-33 facilitates the early development of mononeuropathic pain by activating ERK signaling pathway. A Western blotting showed that red nucleus p-ERK was increased at 1 week post-SNI, intrarubral injection of anti-IL-33 antibody inhibited the upregulation of p-ERK (n = 6 per group, F = 12.666, P < 0.001). B Western blotting indicated that intrarubral injection of IL-33 promoted the protein expression of p-ERK in naive rats (n = 6 per group, F = 14.495, P < 0.001). C Immunohistochemistry showed that p-ERK was upregulated in the RN of SNI rats (F = 69.719, P < 0.001) and IL-33-induced hypersensitivity rats (F = 40.034, P < 0.001) (n = 4 per group). D Intrarubral administration of ERK inhibitor PD98059 at 1 week post-injury attenuated SNI-induced mononeuropathic pain compared to DMSO control (n = 5-6 per group, F = 102.911, P < 0.001). E Intrarubral pre-injection of PD98059, 30 min before IL-33 administration, relieved IL-33-evoked mechanical hypersensitivity compared to DMSO control (n = 5–6 per group, F = 35.306, P = 0.002). *P < 0.05, **P < 0.01, and ***P < 0.001. Scale bars = 50 μm