RESUMEN
Depression is a kind of psychoaffective disorder，which is mainly characterized by persistent depression and mood disorders. It is related to many factors such as abnormal expression of neurotransmitters，secretion of inflammatory cytokines，changes in neuronal pathways，persistent disorder of hypothalamus-pituitary-adrenal （HPA） axis，changes of intestinal flora environment，abnormal mitochondria structure，and many other factors，which cause serious damage to human health. At present，western medicine is mainly treated with antidepressant drugs in clinical practice，which can exert short-term efficacy，but long-term use will cause adverse side effects. Traditional Chinese medicine（TCM） emphasizes the holistic view of psychosomatic integration and has rich clinical practice experience，which gives it a certain therapeutic advantages in the prevention and treatment of depression. Moreover，modern research has shown that TCM has played an important role in the prevention and treatment of depression through its multi-target，multi-mechanism and multi-pathway mode of action. In recent years，the study on TCM in treating depression has been deepening，and more and more TCM and TCM compounds have been proved to be able to regulate and improve the pathogenesis of depression and play an antidepressant role. Therefore，this paper systematically sorted out the research literature on TCM in improving the pathogenesis of depression in the past 5 years，and summarized and elaborated these literature according to the following topics：TCM affects the expression of neurotransmitters and their receptors，improves the plasticity of nerve cells and related signaling pathways，regulates the secretion of inflammatory factors and improves the disorder of HPA axis， TCM regulats intestinal flora environment to relieve depression， TCM adjusts the mitochondrial function of TCM to relieve depression. The study found that most of the TCM exert the antidepressant effect mainly by affecting the expression of neurotransmitters and improving neural signaling pathways，while the research on Chinese medicinals regulating and improving the intestinal flora environment and mitochondrial function is relatively rare，which needs further research to provide reference for better exploration of depression in the future.
RESUMEN
Depression is a serious threat to human health. There are grave difficulties in its prevention and treatment. At present, Western medicine has not yet found a definitive and effective therapy for depression. By virtue of its holistic view, rich clinical practice plus less side effects, traditional Chinese medicine(TCM) may have potential advantages in the prevention and treatment of depression. Single-herbal TCM or TCM compound is one of the main methods for TCM to treat depression. The chemical composition of natural medicine is quite complicated, moreover, the composition of TCM compound is more complicated. Therefore, this paper focuses on the role of single-herbal TCM in preventing and treating depression. Many researchers have discovered more TCM with the effect in preventing depression from historical literatures or clinical experience of different doctors. There are four main causes in the pathogenesis of depression: the first is the abnormal expression of monoamine neurotransmitters and their receptors, the second is the depression of nerve cells and relevant signaling pathways, the third is the hypothalamus-pituitary-adrenal axis that continuously intensifies to cause dysfunction and depression, and the fourth is the abnormal secretion of cytokines. Which mechanism does TCM work through? The meridian tropism theory is an important guiding principle in the clinical use of TCM. Is there a certain relationship between the different meridian tropisms and different pharmacological mechanisms of TCM? To solve these two basic problems, this paper systematically summarizes all the literatures on the mechanism of TCM in the prevention and treatment of depression, and uses the chi-square test to analyze the relationship between the TCM and the four mechanisms of action. This exploration may contribute to further clinical and experimental research on the prevention and treatment of depression with TCM.