Figure 5.

DNA methyltransferase enzymes are involved E₂-induced memory enhancement. (A) Bilateral infusion of E₂ (5 μg/hemisphere) into the dorsal hippocampus significantly increased levels of DNMT3B protein in the dorsal hippocampus relative to vehicle four hours after infusion (*p < 0.05). This increase was blocked by concurrent infusion of garcinol (#p < 0.05 relative to the E₂ group), suggesting that histone acetylation is necessary for E₂ to increase DNMT3B levels in the dorsal hippocampus. Garcinol alone had no effect on DNMT3B levels. Inset illustrates representative Western blot images. DNMT3B protein was normalized to β-actin. Reprinted with permission from (32). (B) Bilateral infusion of 5-AZA (100 μg/hemisphere) into the dorsal hippocampus administered immediately, but not three hours, after training significantly increased the time spent with the novel object relative to chance (*p < 0.05), suggesting that DNA methyltransferase enzymes regulate novel object recognition within a three-hour time window after training. 5-AZA blocked the memory enhancing effect of E₂, indicating that DNMT enzymes regulate the memory-enhancing effects of E₂. Reprinted with permission from (33). Bars in both panels represent the mean ± SEM.