Figure 1.

Peroxynitrite mediates NO donor-induced mechanical hypersensitivity in stress-primed mice. A, A schematic of the stress paradigm used is shown. Mice were subjected to repeated restraint stress or control conditions and tested for facial allodynia via von Frey assessment and mean grimace scores. Upon returning to baseline thresholds 14 d after stress, mice received a 30 mg/kg intraperitoneal injection of a PN scavenger (MnTBAP), a PN decomposition catalyst (FeTMPyP), or vehicle (PBS) 30 min before injection of the NO donor SNP (0.1 mg/kg, i.p.) and were again tested for facial allodynia. B, D, MnTBAP and FeTMPyP both significantly attenuated facial hypersensitivity caused by SNP in stress-primed female (B) and male (D) mice. C, E, No differences in grimace scoring were found in either sex (C, E). All control groups received vehicle before SNP. Two-way ANOVA followed by Bonferroni’s post hoc analysis revealed significant differences in the priming phase between stressed mice that received vehicle before SNP and stressed mice that received MnTBAP (denoted by *) or FeTMPyP (denoted by †) before SNP. n ≥ 6 for all groups in B and C; n = 8 for all groups in D and E. Data are represented as the mean ± SEM. Table 1, see for F-values. *†p < 0.05, **p < 0.01, ***†††p < 0.001, ****††††p < 0.0001.