Figure 4. The effect of melatonin on NR2A, NR2B, and CaMKII protein levels in the hippocampus (A, C, E) and the PFC (B, D, F) of aged mice. Mice were divided into three groups including the young control (2 months old), aged (22 months old) and melatonin-pretreated (10 mg/kg daily melatonin started from 16 to 22 months old) mice. Mice were sacrificed, brains were removed, hippocampus and prefrontal cortex were dissected and kept at -80 °C until use. The protein levels of NR2A, NR2B, and CaMKII were determined by Western blot analyses. Representative bands from different groups are shown. The band densities were normalized to actin. The ratios were calculated as a percentage of the respective value of the control group. A one-way ANOVA was performed for statistical analysis. Data represent the mean ± S.E.M. from 4 mice. *p < 0.05, **p < 0.01 and ***p < 0.001 compared with young adult mice, and #p < 0.05 compared with aged mice.