Hippocampal overexpression of chordin protects against the chronic social defeat stress-induced depressive-like effects in mice.

Depression is a serious and worldwide neuropsychiatric disesase, and developing novel antidepressant targets beyond the monoaminergic systems is now popular and necessary. Bone morphogenetic protein (BMP) signals modulate numerous developmental, physiological, and homeostatic processes. The functions of BMPs are also regulated by secreted extracellular antagonists such as chordin and noggin. Chordin has abundant expression in adult brain, and may play critical role in the central nervous system. In this study, the chronic social defeat stress (CSDS) model of depression, various behavioral tests, western blotting, quantitative real-time reverse transcription PCR, immunohistochemistry, recombinant mouse chordin protein and AAV-Chordin-EGFP were together used to explore the role of chordin in the pathogenesis of depression. It was found that CSDS significantly decreased the expression of chordin in the hippocampus but not other related brain regions. Moreover, both pharmacological and genetic overexpression of hippocampal chordin fully protected against the CSDS-induced depressive-like effects in mice. Collectively, hippocampal chordin could be a novel antidepressant target, and this study further highlights the importance of the hippocampal BMP system in the pathophysiology of depression.