Abstract
Chronic stress is an environmental risk factor for depression and causes neuronal atrophy in the prefrontal cortex (PFC) and other brain regions. It is still unclear about the molecular mechanism underlying the behavioral alterations and neuronal atrophy induced by chronic stress. We here report that phosphatase and tensin homolog deleted on chromosome ten (PTEN) is a mediator for chronic stress-induced depression-like behaviors and neuronal atrophy in mice. One-month chronic restraint stress (CRS) up-regulated PTEN signaling pathway in the PFC of mice as indicated by increasing levels of PTEN, p-MEK, and p-ERK but decreasing levels of p-AKT. Over-expression of Pten in the PFC led to an increase of depression-like behaviors, whereas genetic inactivation or knockdown of Pten in the PFC prevented the CRS-induced depression-like behaviors. In addition, systemic administration of PTEN inhibitor was also able to prevent these behaviors. Cellular examination showed that Pten over-expression or the CRS treatment resulted in PFC neuron atrophy, and this atrophy was blocked by genetic inactivation of Pten or systemic administration of PTEN inhibitor. Furthermore, possible causal link between Pten and glucocorticoids was examined. In chronic dexamethasone (Dex, a glucocorticoid agonist) treatment-induced depression model, increased PTEN levels were observed, and depression-like behaviors and PFC neuron atrophy were attenuated by the administration of PTEN inhibitor. Our results indicate that PTEN serves as a key mediator in chronic stress-induced neuron atrophy as well as depression-like behaviors, providing molecular evidence supporting the synaptic plasticity theory of depression.