Different Mechanisms of Antidepressant Effect in the Scope of Plant-Based Medicines

Major depressive disorder (MDD) is a severe threat to health, impacting 3.8% of the population globally. Current treatment for MDD is synthetic drugs, which exert little response in some patients and show some side effects. With its mild actions of treatment, plant-based medicine (PBM) is a novel perspective for MDD therapy. This review demonstrates and summarizes seven antidepressant mechanisms: monoamine neurotransmitter regulation, hypothalamus-pituitary-adrenal (HPA) axis regulation, inflammation regulation, brain-derived neurotrophic factor (BDNF) regulation, oxidative stress regulation, gut microbiota regulation, and neuroplasticity regulation. Some typical PBMs function in these mechanisms, which are listed. This review shows that PBMs could treat MDD through multiple mechanisms, and ingredients in PBMs work interactively and integrally when treating MDD. The antidepressant effect of PBM is emphasized, and a deeper insight into the mechanisms involved is offered. PBM will have greater acceptance and a larger market, relieving the suffering of patients, with more clinical trials completed and more promotion done.