Confocal microscopy pictures of DHE labelling in spinal cord dorsal horn of 15 mg/kg capsaicin-treated (C, D) and control (A, B) rats, pre-treated for 7 days with the potent antioxidant N-acetyl-L-cysteine (1 g/kg/day) (B, D) or its vehicle (A, C). Nuclei were labelled with TO-PRO-3 (blue) and superoxide anion with DHE (red). Scale = 31.75 μm. Data represent the means ± S.E.M. of at least 4 sections/rat from 4 rats/group. Comparison with control + vehicle (*) or capsaicin + vehicle (+) is indicated by: * + P < 0.05.