Hippocampal alpha-synuclein mediates depressive-like behaviors

Area of Science:

• Neuroscience
• Molecular Biology
• Psychiatry

Background:

• Alpha-synuclein (α-syn), encoded by SNCA, is vital for neurotransmission and neuroplasticity.
• Altered SNCA expression is linked to major depressive disorder (MDD), but its pathogenic role is unclear.

Purpose of the Study:

• To investigate the role of SNCA in the pathogenesis of MDD.
• To elucidate the molecular mechanisms underlying SNCA's contribution to depression.

Main Methods:

• Quantified SNCA expression in MDD patients and a mouse model.
• Utilized chronic restraint stress (CRS) to induce depressive behaviors in mice.
• Manipulated SNCA expression (over-expression and knockout) in the mouse hippocampus.
• Examined synapse loss, neuronal death, microglial activity, and inflammation.

Main Results:

• SNCA expression was upregulated in MDD patients, depressive mice, and following CRS.
• Hippocampal SNCA overexpression induced depressive behaviors; SNCA knockout reversed CRS-induced behaviors.
• SNCA promoted synapse loss and neuronal death in the hippocampus, potentially via complement-mediated microglial activation and inflammation.

Conclusions:

• Hippocampal SNCA and the complement system are implicated in MDD pathogenesis.
• SNCA's role in microglial-mediated inflammation offers novel therapeutic targets for depression.