Effect of Suanzaoren Tang on Learning， Memory and Expression of Proteins Related to Hippocampal Synaptic Plasticity in PCPA-induced Insomnia Rat Model / 中国实验方剂学杂志

ABSTRACT

ObjectiveTo observe the effects of Suanzaoren Tang on the behavior， growth-associated protein-43 （GAP-43）， postsynaptic density protein-95 （PSD-95）， and synaptophysin Ⅰ （SynⅠ） of insomniac rats induced by p-chlorophenylalanine （PCPA）， and to investigate the mechanism of Suanzaoren Tang in improving the behavior of the insomniac rats. MethodSeventy-two SD rats were randomly assigned into 6 groups （12 rats in each group）： control group （normal saline）， PCPA （0.35 g·kg-1·d-1） group， estazolam （2.7×10-4 g·kg-1·d-1） group， and low-， medium-， and high-dose （3.25， 7.5， 15 g·kg-1·d-1， respectively） Suanzaoren Tang groups. The rat model of insomnia was established by intraperitoneal injection of PCPA and then the rats were administrated with corresponding drugs for 7 continuous days. The Morris water maze and Y-maze were used to test the learning and memory functions， and the open field to test anxiety. Histopathological changes in the hippocampus were observed via hematoxylin-eosin （HE） staining. The mRNA and protein levels of GAP-43， PSD-95， and SynⅠ in hippocampus were determined by real-time fluorescence quantitative polymerase chain reaction (Real-time PCR)， Western blot， and immunohistochemistry （IHC）. ResultCompared with the control group， the PCPA group showcased long escape latency， shortened time in the quadrants， and decreased times of crossing the platform in Morris water maze， decreased alternation correct rate was significantly Y-maze， and increased distance， mean velocity， and time in center of the open field test （P<0.01）. Furthermore， the PCPA-treated rats showed obvious pathological damage in the hippocampus and down-regulated mRNA and protein levels of GAP-43， PSD-95， and SynⅠ in hippocampus （P<0.01）. Compared with the PCPA group， the treatments with estazolam and different doses of Suanzaoren Tang improved the rat performance in Morris water maze， Y-maze， and open field test （P<0.05， P<0.01）， alleviated the hippocampal damage， and up-regulated the mRNA and protein levels of GAP-43， PSD-95， and SynⅠ （P<0.05， P<0.01）. ConclusionSuanzaoren Tang may alleviate the learning and memory disorders and anxiety in PCPA-induced insomnia rat model by up-regulating the mRNA and protein levels of hippocampal synaptic plasticity-associated proteins GAP-43， PSD-95， and SynⅠ.