Figure 3. Exogenous proBDNF induces pain hypersensitivity and spinal cord activation in mice.
(A) Dosage effect of exogenous proBDNF protein on PWT by injection of proBDNF protein into the plantar (*P < 0.05, **p < 0.01 versus baseline, one-way ANOVA followed by Dunnett’s Multiple Comparison post hoc test, n = 10–12 per group). (B) Ectopic overexpression of proBDNF by intra-plantar injection of Ad-proBDNF or Ad-EGFP reduces PWT dramatically in Kunming mice. (a) Representative proBDNF Western blot (upper panel) and its semi-quantitative analysis (lower panel, *P < 0.05, ***p < 0.001 versus control, ###p < 0.001 versus indicated groups, one-way ANOVA followed by Tukey’s Multiple Comparison post hoc test, n = 4 per group); (b) Representative fluorescent images after delivery of Ad-EGFP. Scale bar, 50 μm, 3 replicates, n = 3 per group; (c) PWT at 7 days post-injection of Ad-proBDNF or Ad-EGFP control (***p < 0.001 versus Ad-EGFP, student’s t test, n = 7 per group). (C) Co-injection of proBDNF (0.1 μg), but not mBDNF (0.1 μg) restored the biphasic nociceptive response after low-concentration of formalin (0.5%) intra-plantar injection (*p < 0.05versus vehicle, two-way ANOVA followed by Bonferroni’s Multiple Comparison post hoc test, n = 10–12 per group). (D) Exogenous proBDNF (1 μg) intra-plantar injection induces ERK activation in the ipsilateral spinal cord dorsal horn at 3 h post-injection, Scale bar, 50 μm, n = 3 per group, 3 replicates. (E) Spinal p-ERK expression at 3 h after proBDNF (1 μg) intra-plantar injection. (a) Representative Western blot and (b,c) their semi-quantitative analyses of p-ERK, (*p < 0.05, **p < 0.01 versus proBDNF-R, one-way ANOVA followed by Dunnett’s Multiple Comparison post hoc test, n = 3 per group). Data bars represent mean ± s.e.m.