Figure 5. Forest plot comparing changes in antioxidant enzyme activity between MT-treated and vehicle-treated groups. Compared with vehicle treatment, (A) CAT activity was unchanged in the MT-treated group, (B) GPx activity was significantly enhanced in the MT-treated group, and (C) SOD activity did not differ in the MT-treated group. The unit for catalase and SOD are μmol/mg, and U/mg, respectively. For GPx, the unit is nmol/min/mg in Carretero M et al. and mU/min/mg in Okatani Y et al. The prism represents the overall statistical results of the experimental data, squares represent the weight of each study, and horizontal lines represent the 95% CIs for each study. MT, melatonin; CAT, catalase; GPx, glutathione peroxidase; SOD, superoxide dismutase; CI, confidence interval; SD, standard deviation; IV, independent variable.