Fig 1: Glutathione peroxidase (GPx) activity is increased after spinal cord injury (SCI). Two enzymes that use and recycle reduced glutathione (GSH) to sequester reactive oxygen species (ROS) were evaluated using activity assays (A–D) and Western blots (E–J) to determine how age and injury effect protein function and expression. (A,B) The GPx activity is significantly increased with age between sham-mice at one day post-injury (dpi) but only significantly increased after SCI in 4-month-old (MO) mice at one and here dpi. (C,D) Glutathione reductase (GR) was not increased after SCI relative to sham controls but was higher in 14- compared with 4-MO mice after SCI. (E–H) While increases in enzyme activity were found for GPx and GR, no differences were found at the level of protein expression at either day. Assessments were performed using two-way analysis of variance with Sidak pair-wise comparisons as post hoc. n = 9–10/group. Graphs represent mean ± standard error of the mean. *p < 0.05.