Fig. 4

Adcyap1 siRNA or PACAP6-38 promotes pain hypersensitivity and inhibits axonal outgrowth following SNC. A Schematic diagram for the measurement of nociceptive responses after intrathecal administration of Adcyap1 siRNA. B The expression of Adcyap1 in DRGs of the control siRNA (n = 3) and Adcyap1 siRNA (n = 4) groups. C, D Time course of mechanical threshold (C) and allodynia score (D) of the ipsilateral hind paw of the control siRNA (n = 13) and Adcyap1 siRNA (n = 10) groups, with area under the curve (AUC) analysis (1–3 days) in the right panel. E Schematic diagram for the investigation of axonal outgrowth of DRG neurons after intrathecal administration of Adcyap1 siRNA. F Representative images and quantification of axonal outgrowth in acute-dissociated DRG neurons at 3 days post-SNC of the control siRNA (n = 3) and Adcyap1 siRNA (n = 3) groups. Scale bar, 50 μm. G Schematic diagram for the measurement of nociceptive responses after intrathecal administration of Pacap6-38. H, I Mechanical threshold (H) and allodynia score (I) of the ipsilateral hind paw at 1 day post-SNC for the scramble (n = 9), 4 μg PACAP6-38 (n = 10), 13 μg PACAP6-38 (n = 7), and 40 μg PACAP6-38 (n = 10) groups. J Schematic diagram for the investigation of axonal outgrowth of DRG neurons clustered with Pacap6-38. K Representative images and quantification of axonal outgrowth in acute-dissociated DRG neurons from naïve rats cultured with scramble (n = 3) or PACAP6-38 (n = 3) for 3 days. Scale bar, 100 μm. Data are represented as mean ± SEM. Unpaired t test in B, the right panel of C and D, F, and K; two-way ANOVA with Sidak’s multiple-comparisons test in the left panel of C and D; one-way ANOVA with Tukey’s multiple comparisons test in H and I. *P < 0.05, **P < 0.01, ***P < 0.001. n.s., no significant difference