Antidepressant-Like Effect and Mechanism of Ginsenoside Rd on Rodent Models of Depression

Background: There is growing evidence to suggest that ginsenoside Rd (GRd) has a therapeutic effect on depression, but the specific mechanisms behind its activity require further study. Objective: This study is designed to investigate the antidepressant-like effect and underlying mechanisms of GRd. Methods: In this study, the behavioral despair mouse model of depression and chronic unpredictable mild stress (CUMS) rat model of depression were established to explore the effects of GRd on depression-like behavior and its underlying mechanisms. Behavioral tests were used to evaluate the replication of animal models and depression-like behaviors. The hypoxia-inducible factor-1 alpha (HIF-1 alpha) blocker 2-methoxyestradiol (2-ME) was injected to determine the role of HIF-1 alpha in the antidepressant-like effect of GRd. In addition, molecular biology techniques were used to determine the mRNA and protein expression of HIF-1 alpha signaling pathway and synaptic plasticity-related regulators, that is synapsin 1 (SYN 1) and postsynaptic density protein 95 (PSD 95). In silico binding interaction studies of GRd with focused target proteins were performed using molecular docking to predict the affinity and optimal binding mode between ligands and receptors. Results: Our data show that GRd significantly reversed depression-like behavior and promoted mRNA and protein expression of HIF-1 alpha signaling pathway and synaptic plasticity-related regulators. However, the antidepressant-like effect of GRd disappeared upon inhibition of HIF-1 alpha expression following administration of 2-ME. Furthermore, molecular docking results showed that GRd possessed significant binding affinity for HIF-1 alpha, VEGF, and VEGFR-2. Conclusion: Our results show that GRd exhibits significant antidepressant-like effect and that HIF-1 alpha signaling pathway is a promising target for the treatment of depression.