Figure 1. TOW mice exhibited ongoing spontaneous pain, evoked pain, and activation of spinal PKCδ.

(A) Lidocaine (0.04%, i.t.) induced CPP in TOW (hβ^S/hβ^S) SCD mice. TOW mice spent significantly more time in lidocaine-paired chambers, whereas nonsickle control mice showed no chamber preference. (B) Difference scores between test time and preconditioning (pre) time confirmed that hβ^S/hβ^S, but not hβ^A/hβ^A, mice developed lidocaine CPP. (C) TOW mice displayed significantly reduced paw withdrawal threshold to von Frey filaments when compared with hβ^A/hβ^A mice. (D) In response to noxious radiant heat, TOW mice showed significantly shorter paw withdrawal latency compared with h^A/hβ^A mice. Data were analyzed by ANOVA followed by Dunnett’s t test. Two-way ANOVA (pairing vs. treatment) and post hoc Bonferroni’s test were used to analyze CPP data. Difference scores were analyzed by 2-tailed paired t test. ***P < 0.001 vs. hβ^A/hβ^A. n = 8/group. (E) Immunohistochemistry showed plasma membrane translocation of PKCδ (indicated by solid arrows) in the superficial lamina region of the dorsal spinal cord in TOW, but not hβ^A/hβ^A, mice. PKCδ fluorescent intensity across representative cells (indicated by dashed arrows) is shown. Red, PKCδ; green, NeuN. Scale bars: 20 μm. n = 15 slices from 3 mice.