Polygalae radix extract ameliorates behavioral and neuromorphological abnormalities in chronic corticosterone-treated mice

Aim: Polygalae radix is a traditional herbal medicine used for treatment of anxiety or amnesia in several East Asian cultures. In this study, the mechanisms underlying the effects of Polygalae radix extract (PRE) on brain dysfunction such as depressive symptoms and cognitive impairment were investigated. Methods: PRE (20 mg/kg/day, p.o.) was given for 14 days in mice treated chronically with corticosterone (CORT). Depression-like behavior in the forced swim test, spatial memory in the Barnes maze test, hippocampal neurogenesis, dendritic spine density and mRNA expression for neurotrophic factors were evaluated. Results: PRE reversed depression-like behavior, and also reversed the impairment in dendritic spine maturation and the decrease in mRNA expression for glial cell line-derived neurotrophic factor (GDNF) in the hippocampus and nucleus accumbens of chronic CORT-treated mice, but did not affect impaired spatial memory or decreased hippocampal neurogenesis. Conclusion: Polygalae radix ameliorates depressive symptoms via GDNF-induced spine modification in the hippocampus and nucleus accumbens.