PTEN and major depressive disorder: Dex is a synthetic glucocorticoid agonist and chronic Dex treatment is widely used for inducing depression-like behaviors in rodents53–55, and thus it was used to explore: (i) how the PTEN levels are changed in Dex-treated mice, and (ii) whether suppressing PTEN activity is able to attenuate the depression-like behaviors in Dex-treated mice.