Inhibition of PI3K prevented and reversed pain behavior induced by i.t. ephrinB1-Fc.

<p>PI3K inhibitors were injected at 0.5-h before or after ephrinB1-Fc injection. Paw withdrawal latency to the radiant heat and paw withdrawal threshold to mechanical stimuli were recorded at 0.5-h, 1-h, 2-h, 4-h, 8-h, 24-h and 48-h after ephrinB1-Fc (0.5 µg) injection in the pre-treatment experiment and at 0.5-h, 1-h, 2-h, 4-h, and 8-h after PI3K inhibitors in post-treatment experiment. (A,B) Pre-treatment with various dose of wortmannin (0.016, 0.08, and 0.4 µg) or LY294002 (0.2, 1, and 5 µg) prevented ephrinB1-Fc-induced thermal hyperalgesia (Top) and mechanical allodynia (bottom) in a dose-dependent manner. The calculated area under the curve (AUC) (−2–24 h) (inside bar figure) was significantly increased in W0.4-, W0.08-, LY5- and LY1-ephrinB1-Fc group in PWL test, and in W0.4-, LY5- or LY1-ephrinB1-Fc group in PWT test, *<i>P</i><0.05, **<i>P</i><0.01 when compared with DMSO-ephrinB1-Fc group, n = 8 mice in each group. (C,D) Post-treatment with wortmannin (0.016, 0.08, and 0.4 µg) or LY294002 (0.2, 1, and 5 µg) dose-dependently reversed the established thermal hyperalgesia (top) and mechanical allodynia (bottom) by ephrinB1-Fc (0.5 µg).Compared with ephrinB1-Fc-DMSO group, the calculated area under the curve (AUC) (−2–8 h) (inside bar figure) was significantly increased in ephrinB1-Fc-W0.4-, -W0.08, –LY5,or –LY1 group in PWL test, and in ephrinB1-Fc-W0.4, -W0.08,or –LY5 group in PWT test, *P<0.05, **P<0.01 compared with ephrinB1-Fc-DMSO group, n = 8 mice in each group.