Paeoniflorin attenuates impairment of spatial learning and hippocampal long-term potentiation in mice subjected to chronic unpredictable mild stress

Rationale and objective Paeoniflorin has been reported to exhibit antidepressant-like effects in several animal model depression; and it also exerts a neuroprotective effect. In the present study, we investigated the effects of paeoniflorin administration on depression-like behaviors and cognitive abilities in mice subjected to chronic unpredictable mild stress (CUMS), an animal model associated with depressive disorders and cognitive deficits. Methods We administered paeoniflorin (20 mg/kg), which is the main active constituent extracted from Paeonia lactiflora Pall. and exerts multiple pharmacological actions, to CUMS mice. Subsequently, animals were subjected to tests of depression-like behavior including the sucrose preference test, the forced swimming test and the tail suspension test. The Morris water maze (MWM) task was applied to evaluate learning and memory capacity. Hippocampal CA1 long-term potentiation (LTP) was recorded. Dendritic spine density and the expression levels of brain-derived neurotrophic factor (BDNF) and postsynaptic density protein 95 (PSD95) in the hippocampus were also investigated. Results The administration of paeoniflorin protected against CUMS-induced depression-like behavior. Paeoniflorin also improved the performance of CUMS mice in the MWM. The impairment of hippocampal CA1 LTP caused by CUMS was also reversed. Furthermore, paeoniflorin administration prevented decreases in dendritic spine density and in the expression of BDNF and PSD95 in the hippocampus of CUMS mice. Conclusion Our observations suggest that paeoniflorin is a potential antidepressant that protects against cognitive impairment in depression.