BDNF and major depressive disorder: Furthermore, since the hippocampus is critical for stress, learning and memory processes in depression and in the antidepressant response to pharmaco therapy [13], the corresponding changes in inflammatory cytokines (TNF-α, IL-6, IL-10), apoptosis cytokines (P53, Bax, Bcl2, caspase-3) and neurotrophin (BDNF) in the hippocampus were evaluated along with the behavioral evaluation.