SOD1 and Parkinson disease: However, the activity of SOD and GSH content was 36 U/mg protein and 36 mg/g protein, respectively, in rats after ALA treatment, which were higher than those of the PD model group (SOD: treat group, 35.90 ± 2.67, P = 0.0010, GSH: treat group, 35.63 ± 5.10, P = 0.0310) (Figures 3A,B).