Effect and Mechanism of Chaihu Jia Longgu Muli Tang on Hippocampus of Rats with Chronic Stress Depression Based on BDNF/TrkB/CREB Pathway / 中国实验方剂学杂志

ABSTRACT

Objective:To explore the effect of Chaihu Jia Longgu Muli Tang on the hippocampus of rats with chronic stress depression based on the brain-derived neurotrophic factor (BDNF)/tyrosine kinase B (TrkB)/cyclic adenosine phosphate response element-binding protein (CREB) pathway. Method:Sixty SD rats were divided into a blank group (<italic>n</italic>=10) and an experimental group (<italic>n</italic>=50) for the induction of the chronic stress depression model. The rats in the experimental group were further divided into the following five groups a model group， a fluoxetine hydrochloride group (0.003 g·kg^-1), and low-(1.625 g·kg^-1), medium-(3.25 g·kg^-1), and high-dose (6.5 g·kg^-1) Chaihu Jia Longgu Muli Tang groups. The rats were administered correspondingly by gavage once a day for eight weeks. Behavioral tests were performed to evaluate the depression state of the rats before modeling， after modeling， and after drug administration. Hematoxylin-eosin (HE) staining was used to observe the morphological changes in the hippocampus of rats. The immunohistochemical (IHC) staining was used to quantitatively detect BDNF protein expression in the rat hippocampus. The mRNA and protein expression of BDNF， TrkB， and CREB in the rat hippocampus was detected by the real-time fluorescence-based quantitative PCR (Real-time PCR) and Western blot， respectively. Result:Compared with the blank group， the model group showed decreased sucrose preference rate (<italic>P</italic><0.05)， declining horizontal and vertical scores (<italic>P</italic><0.05)， and prolonged immobility time and floating time (<italic>P</italic><0.05). Additionally， HE staining results revealed that hippocampal neuron structure was damaged. IHC staining showed that the mRNA and protein expression of BDNF， TrkB， and CREB was significantly decreased (<italic>P</italic><0.05). Compared with the model group， the fluoxetine hydrochloride group and the Chaihu Jia Longgu Muli Tang groups displayed elevated sucrose preference rate (<italic>P</italic><0.05)， increased horizontal and vertical scores (<italic>P</italic><0.05)， and shortened immobility time and floating time (<italic>P</italic><0.05). Furthermore, the hippocampal neuron structure was significantly repaired. IHC staining showed that the mRNA and protein expression of BDNF， TrkB， and CREB was significantly increased (<italic>P</italic><0.05). Conclusion:Chaihu Jia Longgu Muli Tang can significantly improve the depression-like behaviors of rats after chronic stress stimulation and enhance the regeneration and repair of neurons in the hippocampus. The underlying mechanism may be related to the up-regulation of the BDNF/TrkB/CREB signaling pathway in the hippocampus of rats.