Effect of dorsal root ganglion (DRG) eIF4G2 overexpression on nociceptive thresholds and dorsal horn central sensitisation in naïve mice. (a–d) Effect of microinjection of AAV5-eIF4G2 (eIF4G2) or AAV5-Gfp (GFP) into the unilateral L3 and L4 DRGs on PWFs to 0.07 g (a) and 0.4 g (b) von Frey filament stimuli and on paw withdrawal latencies (PWL) to heat (c) and cold stimuli (d) on the ipsilateral (Ipsi) and contralateral (Contral) sides at the different weeks post-viral microinjection. BL, baseline. n=8 mice per group. Two-way analysis of variance (anova) with repeated measures followed by post hoc Tukey test. Fgroup (3, 196)=204 for 0.07 g, 160 for 0.4 g, and 246 for heat. Fgroup (1, 98)=819 for cold. ∗∗P<0.01 vs the AAV5-Gfp group at the corresponding time points on the ipsilateral side. (e and f) Effect of microinjection of AAV5-eIF4G2 or AAV5-Gfp into the unilateral L3 and L4 DRGs on spontaneous ongoing pain as assessed by the CPP paradigm. (e) Time spent in each chamber. (f) Difference scores for chamber preference were calculated by subtracting preconditioning preference time from post-conditioning time spent in the lidocaine-paired chamber. Pre, preconditioning; Post, post-conditioning. n=8 mice per group. Fgroup(3, 56)=71.∗∗P<0.01 vs the corresponding preconditioning by two-way anova with repeated measures followed by Tukey post hoc test (e) or vs the AAV5-Gfp group by two-tailed, independent Student's t test (f). (g) Levels of eIF4G2 protein in the ipsilateral L3 and L4 DRGs 8 weeks after microinjection of AAV5-eIF4G2 (eIF4G2) or control AAV5-Gfp (GFP). n=6 mice per group. ∗∗P<0.01 vs the AAV5-Gfp group by two-tailed independent Student's t test. (h) Effect of microinjection of AAV5-eIF4G2 (eIF4G2) or AAV5-Gfp (GFP) into the unilateral L3 and L4 DRGs on the levels of p-ERK1 and 2, total ERK1 and 2, and GFAP in the ipsilateral L3 and L4 dorsal horn 8 weeks after viral microinjection. Representative Western immunoblots (left panels) and a summary of the densitometric analysis (right graphs) are shown. n=3 mice per group. ∗∗P<0.01 vs the corresponding AAV5-Gfp group by two-tailed, independent Student's t test. AAV5, adeno-associated virus 5; CCP, conditioned place preference; eIF4G2, eukaryotic initiation factor 4 gamma 2; GAPDH, glyceraldehyde 3-phosphate dehydrogenase; GFAP, glial fibrillary acidic protein; p-ERK, phosphorylated extracellular signal-regulated kinase 1; PWF, paw withdrawal frequency; PWL: paw withdrawal latency.