In a mouse model of depression induced by chronic social defeat stress [49], chronic administration of imipramine, a commonly used antidepressant, induced long-lasting histone H3 acetylation at the P3 and P4 promoters and H3-K4 dimethylation at the P3 promoter of the brain-derived neurotrophic factor (Bdnf) gene, with increased expression in the hippocampus. This evidence concerns the gene BDNF and depressive symptom measurement.