Objective: To explore the underlying mechanism of acupuncture in the treatment of vascular dementia(VD).Methods: A total of 28 male rats were randomized into normal group(n=6)

sham-operation group(n=6)

model group(n=5)

acupuncture group(n=6) and non-acupoint group(n=5).Cerebral multi-infarct VD model was established by injecting blood emboli into the internal carotid artery."Tanzhong"(CV 17)

"Zhongwan"(CV 12)

"Qihai"(CV 6)

bilateral "Xuehai"(SP 10)

bilateral "Zusanli"(ST 36) and bilateral non-acupoints(at hypochondrium) were punctured respectively

once daily

18 times altogether(3 weeks).The nNOS mRNA expression and nNOS activity were assayed by using in situ hybridization and immunohistochemical methods separately.Results: Both in situ hybridization and immunohistochemical assays displayed that in comparison with normal group

the integral optic density(IOD) values of nNOS mRNA and nNOS of hippocampal tissue in VD model group and non-acupoint group were significantly bigger(P<0.01

0.05);and the IOD values of these two indexes of acupuncture group were significantly lower than those of model group(P<0.01);no significant differences were found among normal

sham-operation and acupuncture groups

and between non-acupoint and model groups in the IOD values(P>0.05)

suggesting that acupuncture could significantly down-regulate the elevated expression of hippocampal nNOS mRNA and nNOS in VD rats

and the effect of acupuncture of the abovementioned acupoints was markedly superior to that of non-acupoints.Conclusion: Acupuncture can markedly inhibit cerebral infarction induced over expression of hippocampal nNOS mRNA and nNOS

which may contribute to its effect in protecting cerebral neurons from injury and improving learning competency in multi-infarct VD rats.