Cat enzyme activity in serum and brain tissue of mice in the control group was 36.78 ± 5.15 and 6.52 ± 0.58 units/ml, respectively, while this level was significantly reduced in the PD group (14.48 ± 4.019 in serum and 2.12 ± 0.81 in brain tissue; P < 0.001), indicating an increase in the level of oxidative stress caused by disease induction. This evidence concerns the gene CAT and Parkinson disease.