Fig. 5

Effect of sulfasalazine administration on the spinal expression of xCT and the pain hypersensitivity following PSNL surgery. Three (A) and seven (B) days post-surgery, the ipsilateral and contralateral dorsal horn quadrants of the lumbar spinal cord of lesioned-xCT^+/+ mice were dissected and used for RT-qPCR. xCT mRNA was evaluated, normalized to the mean of 3 housekeeping genes (RPL-19, Ywhaz, HPRT-1) and expressed as a percentage of the respective contralateral mRNA level. Pain hypersensitivity was assessed for the ipsilateral (C, D, F, G) and contralateral (E, H) hind paw at baseline (BL) and for 7 days following PSNL surgery. The 50% PWT to mechanical stimulation was used to determine allodynia (C-E), whereas the PWL to thermal stimulation was used as a read-out of hyperalgesia (F-H). Panel D and G depict the area under the curve for the ipsilateral 50% PWT and PWL, respectively. Data are presented as arithmetic mean with SEM (C, E, F, H) or geometric means with SD (D, G) (5 animal per group for mRNA analysis and 6 animal per group for behavioral tests). Statistical analyses were performed using a one-way ANOVA (A, B) or a two-way ANOVA (D, G) model with repeated measures (C, E, F, H). Main and interaction effects of the two-way ANOVA model are indicated below the graphs. When statistically significant interaction was detected, Tukey’s pairwise comparisons were conducted. P-values for significant effects are reported on the graphs. In panel C and F, * indicates a significant difference between SAS-treated wild-type (xCT^+/+ SAS) and SAS-treated transgenic mice lacking xCT (xCT^−/− SAS), ^# indicate a significant difference between SAS-treated and saline-treated animals (within the same genotype). PSNL partial sciatic nerve ligation; PWT paw withdrawal threshold; PWL paw withdrawal latency; AUC area under the curve; I ipsilateral; C contralateral; SAS sulfasalazine; G genotype effect; T treatment effect; G*T interaction effect