Fig. 5

Repeated intrathecal injection of PACAP38 attenuates mechanical allodynia and promotes axonal regeneration following SNC. A Schematic diagram for the measurement of nociceptive responses after intrathecal administration of PACAP38 in the acute phase of SNC. B, C Time course of mechanical threshold (B) and allodynia score (C) of the ipsilateral hind paw after intrathecal administration of scramble (n = 8) or PACAP38 (n = 8) in the acute phase of SNC. D Schematic diagram for the measurement of nociceptive responses after intrathecal administration of PACAP38 in the chronic phase of SNC. E, F Time course of mechanical threshold (E) and allodynia score (F) of the ipsilateral hind paw after intrathecal administration of scramble (n = 8) or PACAP38 (n = 8) in the chronic phase of SNC. G Schematic diagram for the investigation of axonal outgrowth of DRG neurons after intrathecal administration of PACAP38. H Representative images and quantification of axonal outgrowth in acute-dissociated DRG neurons from rats at 3 days post-SNC for the scramble (n = 3) and PACAP38 (n = 3) groups, immunostained for βIII-tubulin. Scale bar, 50 μm. I Representative images of longitudinal sections of the two crushed sciatic nerve branches (TN and CPN) in the scramble and PACAP38 groups at 3 dpi, immunostained for GAP43 (regenerated nerve fibers) and NF200 with DAPI staining. Scale bar, 1 mm. The dashed line indicates the crush site. J Quantification of axonal regeneration with the regeneration index measured as GAP43 intensity normalized to the crush site for the scramble (n = 5) and PACAP38 (n = 5) groups. DGRs, DRG neurons. Data are represented as mean ± SEM. Two-way ANOVA with Sidak’s multiple-comparisons test in B, C, E, F, and J; unpaired t-test in H. *P < 0.05, **P < 0.01, ***P < 0.001. n.s., no significant difference