Hippocampal alpha-synuclein mediates depressive-like behaviors

Alpha-synuclein (alpha-syn) which encoded by SNCA plays a critical role in the neurotransmission, vesicle dynamics, and neuroplasticity. Alteration to SNCA expression is associated with major depressive disorder. However, the pathogenic mechanism of SNCA in depression remains unknown. Herein, we reported that SNCA was upregulated in the peripheral blood of major depressive disorder (MDD) patients and the depressive mice. Chronic restraint stress (CRS) also up-regulated the SNCA expression in the hippocampus. Moreover, overexpression of SNCA in the hippocampus triggered spontaneous depressive-like behaviors under the nonstressed conditions in mice, and knockout of SNCA could reverse CRS-induced depressive-like behaviors. SNCA led to synapse loss and neuronal cell death in the hippocampus possibly via complement-mediated microglial engulfment and inflammation, and thus contributed to the pathogenesis of depressive disorder. Overall, hippocampal SNCA and complement system are involved in the pathogenesis of depressive disorder and it provides a new perspective for the occurrence of depressive disorder.

Automated summary

The study found that the expression of SNCA is upregulated in major depressive disorder patients and depressive mice, and overexpression of SNCA can lead to depressive-like behaviors in mice under nonstressed conditions, while knockout of SNCA can reverse stress-induced depressive-like behaviors. The study speculates that SNCA may cause synaptic loss and neuronal cell death in the hippocampus possibly through complement-mediated microglial engulfment and inflammation, thus contributing to the pathogenesis of depressive disorder.