Objective To study the effects of Xingshen Yizhi granule on the learning and memory ability and the expression of postsynaptic dense protein 95 (PSD95) and synapsin (SYN) protein in the hippocampus of vascular dementia (VD) rats. 

 Methods Totally forty-five SD rats were randomly divided into control group (n=15),VD group (n=15)and treatment group (n=15).VD rat model was established in the VD group and treatment group with modified intermittent ligation of common carotid artery, and the rats in the treatment group were treated with Xingshen Yizhi granule after membrane formation. The learning and memory ability of three groups of rats were tested by Morris water maze test. The expression of PSD95 and SYN in hippocampal CA1 was detected by immunohistochemical staining.   Results Compared with the control group SD rats, at day 1, day 3 and day 5 of the experiment, the escape latency of SD rats in VD group ［(58.3±17.9), (29.3±7.6) and (17.4±8.7)］ increased significantly［(58.3±17.9), (29.3±7.6) and (17.4±8.7)］. At week 1, week 4 and week 8, the expression of hippocampal PSD95 ［(28.25±5.09), (30.74±5.16) and (32.34±5.43)］ and SYN ［(12.70±6.20), (15.74±6.27) and (22.11±6.34］ protein  decreased significantly. Compared with the VD group, at day 1, day 3 and day 5 of the experiment, the escape latency of SD rats in the treatment group ［(55.7±17.1), (21.4±7.9) and (9.4±4.2)］ decreased significantly. At  week 1,  week 4 and week 8, the expression of hippocampal PSD95 in the treatment group ［(35.63±3.38), (37.84±3.57) and (39.53±3.67)］,SYN ［(25.75±5.79), (28.61±5.93) and (33.18±6.16)］ protein increased significantly. Compared with the control group, the expression of SYN and PSD95 in the hippocampus of the model group decreased significantly (P<0.05).Compared with the model group, the expression of SYN and PSD95 in the hippocampus of the treatment group was significantly higher(P<0.05), but it was still lower than that of the control group.  

 Conclusion Xingshen Yizhi granule can significantly improve learning and memory function and increase synaptic plasticity in VD rats. Its neuroprotective effect may be related to the increased expression of SYN and PSD95 in the hippocampus.