DNMT3A and depressive disorder: The potential importance of excessive Dnmt3a expression in regulating stress responses has been supported by studies showing that overexpression of Dnmt3a in the NAc increases depression- and anxiety-like behaviors, and knocking out Dnmt3a induces antidepressant and anxiolytic-like effects in mice exposed to 3 days of stress (Hodes et al., 2015).