[Effect of "Xiusanzhen" on hippocampal muscarinic cholinergic receptor activity in Alzheimer disease rats].

OBJECTIVE

To explore the effect of "Xiusanzhen" [electroacupuncture (EA) of bilateral "Yingxiang" (LI 20) and "Yintang" (EX-HN 3)] on activities of hippocampal 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: 3.5 mm, L:2 mm, H: -2.8 mm) of Abeta(1-40) starch-like peptide (10 microg/2 microL) 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 (5 mm anterior to the bregma, L, R: 2 mm). 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.