Objective: To investigate the effects of polysaccharide from Corni Fructus on learning and memory ability

protein expression levels of brain derived neurotrophic factor(BDNF) and tyrosine kinase B(TrkB) in hippocampus

and hippocampal long-term potentiation (LTP) of the aging model rats. Method: Totally 40 clean SD rats were randomly divided into normal group

model group

low dose group and high dose group by random number table

n=10 in each group. The models of aging rats were established by subcutaneously injecting D-galactose (140 mg·kg-1·d-1). The rats in normal group and model group received normal saline every day

while the rats in low dose group and high dose group were given with polysaccharide from Corni Fructus(0.14

0.28 g·kg-1·d-1

correspondingly) by intragastric administration for 6 weeks. The learning and memory ability of rats was tested by Morris Water Maze. The Schaffer collateral of hippocampal CA3 region was stimulated by high frequency stimulation (HFS)

and LTP in CA1 region of the ipsilateral hippocampus was induced to detect the synaptic plasticity changes of hippocampal neurons in rats. The protein expression levels of BDNF and TrkB in hippocampal neurons were detected by immunohistochemistry. Result: As compared with the normal group

the average escape latency of model group was prolonged significantly

the percentage of swimming distance of the target quadrant in total distance and the frequency of exploration were decreased significantly

the protein expression levels of BDNF and TrkB in the hippocampus were reduced

and the extent of LTP in hippocampus was decreased significantly (P < 0.01). As compared with the model group

the average escape latency of high dose group was decreased significantly; the percentage of swimming distance of the target quadrant in total distance and the frequency of exploration were increased significantly

the protein expression levels of BDNF and TrkB in hippocampus were increased

and the extent of LTP in hippocampus was increased significantly (P < 0.01). Conclusion: Polysaccharides from Corni Fructus may significantly improve the synaptic plasticity in the aging model rats by increasing the protein expression levels of BDNF and TrkB in hippocampus and increasing LTP of hippocampal CA1 region; this may be one of its important mechanisms for improving the ability of learning and memory of the aging rats.