The level of ROS, the expression of NOX2 and NOX4 in the LA, and the concentration of H2O2 and MDA in serum were remarkably increased in the MDD rats versus the CTL rats (p < 0.05, Figures 8B–E,G,I), and the activity of SOD and the ratio of GSH/GSSG in serum were clearly reduced in the MDD rats (p < 0.05, Figures 8F,H). This evidence concerns the gene NOX4 and major depressive disorder.