Objective To study the underlying mechanism of electroacupuncture(EA) in improving learning-memory ability in vascular dementia(VD) rats.Methods SD rats were randomized into control

sham operation(sham)

VD model

non-acupoint and acupoint groups

with 10 cases in each.VD model was established by occlusion of the bilateral common carotid arteries.Morris water maze test was performed to detect the rats' learning-memory ability.The expression of N-methyl-D-aspartate receptor(NMDAR)-2 B mRNA in hippocampal CA 1 region and dentate gyrus was measured by hybridization in situ.EA(2 Hz

1-2 mA)was applied to "Baihui"(GV 20)

"Dazhui"(GV 14) and bilateral "Shenshu"(BL 23) and non-acupoint(the chest-abdominal juncture between the first and the second lumbar vertebrae) for 20 min

once daily for 30 days.Results Self-comparison showed that 6 weeks after modeling

the escape latencies of control and sham groups

and the lingering duration in the 3rd quadrant of water pool of model

non-acupoint and acupoint groups decreased significantly(P<0.05)

while the escape latencies of model

non-acupoint and acupoint groups

and the lingering duration of control and sham groups increased considerably(P<0.05).No significant differences were found between control and sham groups

and among model

non-acupoint and acupoint groups in the escape latency and the lingering duration in the 3rd quadrant(P>0.05).On the 11th week after modeling

compared to their individual escape latencies and lingering duration on the 6th week

the escape latencies of control

sham and acupoint groups shortened obviously(P<0.05)

while the lingering duration in the 3rd quadrant of the same 3 groups postponed significantly(P<0.05).Compared with model group

the escape latency of acupoint group shortened obviously and the lingering duration increased significantly(P<0.05).No significant differences were found between control and sham groups

and between modeland non-acupoint groups in these two indexes(P>0.05).Compared to control/sham group

the grey values of NMDAR-2 B mRNA expression in hippocampal CA 1 region and dentate gyrus in model and non-acupoint groups decreased significantly(P<0.05).Compared to model group

the grey values of NMDAR-2 B mRNA expression in these two brain regions increased markedly(P<0.05).No significant difference was found between control and sham groups

and between model and non-acupoint groups(P>0.05).Conclusion Acupoint-EA is able to improve VD rats' learning-memory ability which may be related to its effect in upregulating the expression of NMDAR-2 B mRNA in hippocampal and dentate gyrus.