Hippocampal BDNF signaling restored with chronic asiaticoside treatment in depression-like mice.

Brain-derived neurotrophic factor (BDNF) plays a key role in the regulation of depression in the brain. Recently, increasing studies have focused on the antidepressant-like mechanism of BDNF and its downstream signaling pathway. A previous study has shown that asiaticoside produced an antidepressant-like action in the mouse tail suspension test and forced swimming test. However, the neurotrophic mechanism that is affected by asiaticoside is unclear. Our present study aimed to verify whether asiaticoside produces an antidepressant-like effect through the activation of BDNF signaling in chronic unpredictable mild stress (CUMS). The results showed that mice treated with asiaticoside for four weeks reversed the decreased sucrose preference and increased immobility time that was observed in CUMS mice. In addition, we found that asiaticoside up-regulated BDNF, PSD-95 and synapsin I expression only in the hippocampus but not in the frontal cortex in both non-stressed and CUMS mice. However, K252a, an inhibitor of BDNF receptor tropomyosin-related kinase receptor B (TrkB), completely abolished the antidepressant-like effect of asiaticoside. Moreover, the expression of hippocampal BDNF, PSD-95 and synapsin I that had increased with asiaticoside also declined with K252a pretreatment. In conclusion, our study implies that it is possible that asiaticoside exerts its antidepressant-like action by activating BDNF signaling in the hippocampus.