Zhi-Zi-Hou-Po decoction alleviates depressive-like behavior and promotes hippocampal neurogenesis in chronic unpredictable mild stress induced mice via activating the BDNF/TrkB/CREB pathway

Zhi-Zi-Hou-Po decoction (ZZHP), a traditional Chinese medicine (TCM) classic recipe, has been extensively applied for the remedy of depression. However, the underlying mechanism of ZZHP hasn't been fully elucidated and it needs to be further clarified. The aim of the study is to uncover the mechanisms of ZZHP's effect on depression. C57BL/6 mice were employed to establish Chronic Unpredictable Mild Stress (CUMS) models. Behavioral tests were conducted for evaluating the antidepressant effects of ZZHP. Then, the monoamine neurotransmitters in the hippocampus through High Performance Liquid Chromatography Electrochemical Detection (HPLC-ECD) were utilized to assess the effect of ZZHP on the maintenance of monoamine neurotransmitter homeostasis. Immunofluorescence staining and Golgi staining were detected to analyze the effects of ZZHP on neuroplasticity in the hippocampus. Western Blot (WB) was utilized to examine the effects of ZZHP on BDNF/TrkB/CREB pathways. Finally, behavioral tests, WB and immunofluorescence staining were repeated after TrkB receptor antagonist was added to further confirm the underlying mechanism. Our results shown that ZZHP attenuated depressive-like symptoms in CUMS mice. Moreover, ZZHP remarkably reversed the reduction and maintained the homeostasis of monoamine neurotransmitters in the hippocampus. Simultaneously, ZZHP protected neuronal synaptic plasticity and promoted hippocampal neurogenesis. Furthermore, ZZHP stimulated the BDNF/TrkB/CREB pathway in the hippocampus. The addition of TrkB receptor antagonist inhibited the antidepressant effects of ZZHP, suggesting that ZZHP could not work without triggering the BDNF/TrkB/CREB pathway. This study demonstrates that ZZHP can alleviate depressive-like behavior and promote hippocampal neurogenesis in CUMS mice via activating the BDNF/TrkB/CREB pathway.