Objective: To investigate the effects of polygona-polysaccharose (PP) upon the synapse structure in hippocampuss region of APP transgenic mice and the related mechanism. Method: Different concentrations of PP solution were Ig given to APP transgenic mice daily for 45 consecutive days

then tissues of hippocampuss CAI region were observed through transmission electron microscope (TEM)

and stereology was adopted to analyze the quantity

sectional area and degeneration of its synapse and the alteration of the quantity of the synapse vesicles involved. Result: The PP treated groups exhibited an obvious increase in synapse quantity (P<0.01)

a decrease in synapse sectional area and degeneration degree

and an increase in synapse vesicles quantity

and the improvement of its synapse had dose-effect relation to some extent. Conclusion: PP is beneficial for the improvement of the synapse structure in hippocampuss CAI region of APP transgenic mice.