Figure 1.

Simplified scheme of BDNF and serotonin interaction in depression. In depression, there exists a complex interplay between BDNF and serotonin. BDNF interacts with the TrkB receptor, thereby exerting its influence on serotonergic signaling pathways. Conversely, these pathways also impact BDNF signaling. Disruptions within these intricate pathways, indicated by red dashed arrows, are observed in major depressive disorder. Consequently, these disruptions contribute to structural changes in the brain, impaired neuroplasticity, compromised synaptic regulation, and reduced levels of both serotonin and BDNF. These cumulative effects ultimately promote or contribute to the development of depressive symptoms.