Figure 6. Forest plot comparing changes in GRx activity and GSH/GSSG ratio between MT-treated and vehicle-treated groups. Compared with vehicle treatment, (A) GRx activity and (B) GSH/GSSG ratio were both significantly enhanced in the MT-treated group. The unit for GRx almost in all studies is nmol/mg, except Nogues MR et al. (nmol/ml). 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; GRx, glutathione reductase; GSH/GSSG, reduced-glutathione/oxidized-glutathione; CI, confidence interval; SD, standard deviation; IV, independent variable.