Fig. 1.
Spinal nerve ligation upregulates spinal phosphorylated upstream frameshift 1 (UPF1) expression accompanied by allodynia-like behaviors. (A) The ipsilateral and contralateral paw withdrawal threshold measured after sham operation (Sham) or spinal nerve ligation. **P < 0.01 versus sham ipsilateral group. ##P < 0.01 versus spinal nerve ligation ipsilateral group on Day –1. Experimental groups, two. Each group, six rats. Two-way ANOVA, group, F(3,20) = 50.72, P < 0.001; time, F(4,80) = 5.73, P < 0.001; interaction, F(12,80) = 11.34, P < 0.001. (B) Representative immunoblotting and statistical analyses (normalized to glyceraldehyde 3-phosphate dehydrogenase [GAPDH]) of phosphorylated UPF1 and total UPF1 in the ipsilateral and contralateral dorsal horn after operation. *P < 0.05, **P < 0.01 versus sham ipsilateral group. ##P < 0.01 versus spinal nerve ligation ipsilateral group on Day –1. Experimental groups: two. Each group: five rats. Total UPF1, two-way ANOVA, group, F(3,16) = 0.04, P = 0.989; time, F(4,64) = 1.13, P = 0.350; interaction, F(12,64) = 1.03, P = 0.437. Phosphorylated UPF1, two-way ANOVA, group, F(3,16) = 5.64, P < 0.001; time, F(4,64) = 13.91, P < 0.001; interaction, F(12,64) = 9.09, P < 0.001. (C) The ipsilateral paw withdrawal threshold measured on Days –1 and 7 after spinal nerve ligation operation in male or female rats. **P < 0.01 versus male group on Day –1. ##P < 0.01 versus female group on Day –1. Experimental groups: four. Each group: six rats. (D) The burrowing activity measured on Days –1 and 7 after spinal nerve ligation operation in male or female rats. **P < 0.01 versus male group on Day –1. ##P < 0.01 versus female group on Day –1. Experimental groups: four. Each group: six rats. (E) Representative immunoblotting and statistical analyses (normalized to GAPDH) of phosphorylated UPF1 in the ipsilateral dorsal horn on Days –1 and 7 after spinal nerve ligation operation in male or female rats. **P < 0.01 versus male group on Day –1. ##P < 0.01 versus female group on Day –1. Experimental groups: four. Each group: five rats. (F) Phosphorylated UPF1 (red), NeuN (green, a neuronal marker), OX-42 (green, a microglial marker), and GFAP (green, a microglial marker) immunoreactivity in the dorsal horn measured on Day 7 after operation. Scale bar, 100 μm. Thickness, 30 μm. Experimental groups: two. Each group: five rats.