Effect of Bushen Tongluo Prescription on Synaptic Plasticity of Hippocampal Neurons of Vascular Dementia Model Rats Based on PI3K/Akt/mTOR Pathway / 中国实验方剂学杂志

ABSTRACT

Objective:To explore the effect of Bushen Tongluo prescription （BSTLP） on the synaptic plasticity of hippocampal neurons in vascular dementia （VD） model rats and its mechanism. Method:SD male rats of SPF grade were selected. The rat model of VD was established by permanent bilateral ligation of the common carotid artery several times. The model rats were randomly divided into a model group， an insulin-like growth factor-1 （IGF-1， 20 μg·kg^-1） group， high-dose （3 g·kg^-1）， medium-dose （1.5 g·kg^-1）， and low-dose （0.75 g·kg^-1） BSTLP groups. A sham operation group was also set. Drugs were administered to rats by gavage once a day for four weeks. The model group and the sham operation group received the same volume of normal saline. After the last administration， all the rats were detected for spatial learning and memory by the Morris water maze. The apoptosis of hippocampal neurons was detected by terminal deoxynucleotidyl transferase （TdT） dUTP nick-end labeling （TUNEL） assay. The changes in synaptic morphological structure and the number of dendritic spines in hippocampal neurons were detected by Golgi's method. The expression levels of phosphatidylinositol 3-kinase （PI3K）， protein kinase B （Akt）， mammalian target of rapamycin （mTOR）， synaptophysin （SYP）， and amyloid precursor protein （APP） in hippocampal neurons were detected by Western blot. Result:Compared with the sham operation group， the model group showed prolonged escape latency， lengthened swimming distance， dwindled the number of times for the platform crossing after platform removal （<italic>P</italic><0.05）， increased apoptotic cells （<italic>P</italic><0.05）， declining synaptic dendritic spines （<italic>P</italic><0.05）， down-regulated expression levels of PI3K， Akt， mTOR， and SYP proteins， and up-regulated expression level of APP protein in hippocampal neurons （<italic>P</italic><0.05）. Compared with the model group， the BSTLP groups and the IGF-1 group showed shortened escape latency and swimming distance， increased number of times for the platform crossing after platform removal （<italic>P</italic><0.05），declining apoptotic cells （<italic>P</italic><0.05）， up-regulated expression levels of PI3K， Akt， mTOR， and SYP proteins， and down-regulated expression level of APP protein in hippocampal neurons （<italic>P</italic><0.05）. Compared with the IGF-1 group， the high-dose BSTLP group showed no significant difference in the escape latency， swimming distance， the number of times for the platform crossing after platform removal， apoptotic cells， synaptic dendritic spines， and expression levels of PI3K， Akt， mTOR， SYP， and APP proteins in hippocampal neurons. However， the differences were significant in the medium-dose and low-dose BSTLP groups （<italic>P</italic><0.05）. Conclusion:BSTLP can improve the learning and memory of rats with VD. The mechanism is presumedly related to the activation of thePI3K/Akt/mTOR pathway and improvement of synaptic plasticity of hippocampal neurons.