Objective To explore the effect of "Xiusanzhen" [electroacupuncture(EA) of bilateral "Yingxiang"(LI20) and "Yintang"(EX-HN3)] on activities of hipppocampal muscarinic cholinergic receptor(mAChR) and the involved neural path in Alzheimer Disease(AD)rats.Methods Forty Sprague Dawley rats were randomly divided into normal control

model

olfactory nerve severing(ONS)-EA of "Xiusanzhen"(ONS-EA) and EA of "Xiusanzhen"(EA) groups.AD model was established by intra-hippocampal injection(AP:3.5mm

L:2mm

H:-2.8mm) of Aβ1-40 starch-like peptide(10 μg/2μL) under the aid of a microsyringe installed in a brain stereotaxis instrument.For rats of the ONS-EA group

the olfactory nerve was severed by using a surgical knife after drilling a hole on the skull(5mm anterior to the bregma

L

R: 2mm).The mAChR density

and its maximum binding capacity(Bmax) and dissociation constant(Kd) of the hippocampus tissue were measured by using radio-ligand binding analysis and Lowry's microamount protein assay.Results In comparison with the normal control group

the hippocampal mAChR density and its Bmax in the model group were decreased remarkably(P<0.05)

while the Kd of M-receptor in the model group was increased remarkably(P<0.05).In comparison with the model group

hippocampal mAChR density and its Bmax in the EA group were up-regulated obviously(P<0.05)

while the Kd of mAChR in the EA group was down-regulated significantly(P<0.05).No significant differences were found between the model and ONS-EA groups in mAChR density and its Bmax and Kd(P>0.05).Conclusion "Xiusanzhen"-EA can effectively up-regulate hippocampal mAChR density and Bmax and down-regulate Kd of M-receptor of hippocampus in AD rats

which is dependent on the intact olfactory nerve pathway.