Effect of Electroacupuncture on Levels of β-amyloid and Neprilysin Proteins in the Cerebral Cortex of Alzheimer's Disease Mice Based on "Mutual Assistance of Kidney and Brain" Theory

Abstract

To observe the effect of electroacupuncture (EA) on the levels of Aβ 1-40 and Aβ 1-42 and neprilysin (NEP) protein in the temporal cortex of SAMP 8 mice with Alzheimer's disease (AD), so as to explore its mechanism underlying improvement of AD based on the theory of "mutual assistance of kidney and brain" in traditional Chinese medicine. Eighteen male SAMP 8 mice were randomly assigned to 3 groups: model, EA and medication (memantine, n＝6/group), and 6 male homologous SAMR 1 mice were used as the normal control group. According to the "mutual assistance of kidney and brain" theory, EA (2 Hz，0.6 mA) was applied at "Baihui"(GV 20), bilateral "Shenshu"(BL 23) and "Taixi"(KI 3) for 15 min, once daily for 8 consecutive weeks. Mice of the medication group were treated with intragastric administration of memantine (20 mg•kg－1•d－1) for 8 weeks. The contents of Aβ 1-40 and Aβ 1-42 in the temporal cortex were assayed using ELISA, and the expression of NEP protein in the temporal cortex was detected using immunohistochemistry and Western blot (WB), separately. The contents of Aβ 1-40 and Aβ 1-42 were significantly higher in the model group than in the control group (P<0.05), and notably lower in both EA and medication groups than in the model group (P<0.05). WB assay showed that the expression level of NEP was significantly down-regulated in the model group relevant to the control group (P<0.05), and obviously up-regulated in both EA and medication groups relevant to the model group (P<0.05). No significant differences were found between the EA and medication groups in the contents of Aβ 1-40 and Aβ 1-42 and in the up-regulated expression levels of NEP protein (P>0.05). Immunohistochemistry stain showed that NEP-positive products mainly expressed in the perikaryon of neurons of the temporal cortex. EA intervention based on "mutual assistance of kidney and brain" theory has a good efficacy in up-regulating NEP expression and down-regulating Aβ 1-40 and Aβ 1-42 levels in the temporal cortex of AD mice, suggesting a potential effectiveness in the prevention and treatment of AD.