Paeoniflorin ameliorates chronic stress-induced depression-like behavior in mice model by affecting ERK1/2 pathway

Depression is a mental and emotional disorder that has made an opening great burden to the society. Paeoniflorin showed remarkable antidepressant-like effects in multiple animal models with depressive disorders. However, the molecule of paeoniflorin on depression is less studied. This study aims to explore the effect and the molecular mechanism of paeoniflorin on depression in a chronic restraint stress (CRS) mice model. CRS model of C57BL/6 J mice was set up. Sucrose preference test (SPT), tail suspension test (TST), open field test (OFT) and forced swimming test (FST) were used to assess depression symptoms. Immunofluorescence staining, quantitative reverse transcription-polymerase chain reaction (qRT-PCR) and western blotting were implemented to detect the expression changes of the proteins involved in extracellular signal-regulated kinase 1/2 (ERK1/2) signaling pathway. Results showed that paeoniflorin treatment decreased the degree of depression in the CRS mice. Further analysis showed that the expression of ERK1/2 proteins was significantly downregulated, while paeoniflorin could elevate the expression of ERK1/2 proteins in CRS mice. Finally, it showed that inhibiting signaling ERK1/2 pathway could aggravate the depressive behavior when treatment with ERK-specific inhibitor U0126, while the condition could be partially relieved when treated with paeoniflorin. In conclusion, the present study demonstrated that paeoniflorin attenuated chronic stress-induced depression-like behavior in mice by affecting the ERK1/2 pathway. These findings provided the basis for the molecular mechanism of paeoniflorin on the effect of depression, which support paeoniflorin might act as an important drug in the treatment of depression.