Antidepressant-like effects of ginsenoside Rg2 in a chronic mild stress model of depression.

Major depression is a common neuropsychiatric disease with high lifetime prevalence and high incidence of suicide. This study aimed to evaluate the antidepressant effects of ginsenoside Rg2 in mice, and the possible mechanism was also determined. A single injection of both Rg2 (10 and 20mg/kg) and fluoxetine (positive control, 20mg/kg) induced notable antidepressant-like effects in the forced swim test and tail suspension test without affecting the locomotor activity of mice, and the tests were done 30min after the injection. Also, repeated daily treatment of Rg2 and fluoxetine for the last 2 weeks fully reversed the chronic mild stress (6 weeks)-induced depressive-like symptoms in mice. Moreover, western blot analysis showed that Rg2 administration significantly increased the BDNF signaling pathway in hippocampus. Importantly, the usage of TrkB shRNA fully blocked the antidepressant effects of Rg2 in mice. Collectively, these results suggest that Rg2 produces an antidepressant-like effect in mice which is mediated, at least in part, through promoting the hippocampal BDNF signaling pathway.