In the current study, depression was manifested by reduction in hippocampal Protein Kinase cAMP-Activated Catalytic Subunit Alpha (PRKACA), Phosphorylated cAMP response element-binding protein (CERB) and Brain derived neurotrophic factor (BDNF) levels, however, there was a rise of hippocampal Phosphodiesterase E4 (PDE4) level. Here, BDNF is linked to major depressive disorder.