Background Acupuncture is a potential therapy for Alzheimer's disease (AD), but its clinical effects and underlying mechanisms are not fully understood. Emerging evidence suggests autophagy is involved in β-amyloid (Aβ) clearance. We hypothesised that electroacupuncture (EA) treatment of AD involves the autophagy pathway in rats.
Methods We injected 2μl Aβ1–40 bilaterally into the hippocampi of 42 rats to establish AD. Rats remained untreated (AD group, n=14) or received 24 EA treatments at GV20+BL23 over 28 days from day 7 post-injection with/without co-treatment with 3-methyladenine (3-MA), an autophagy inhibitor (AD+EA+3-MA and AD+EA groups, respectively, n=14 each). Cognitive function was evaluated by Morris water maze (MWM) testing. Hippocampi were examined by transmission electron microscopy (TEM) and stained with haematoxylin and eosin/transferase dUTP nick end labelling (TUNEL) to assess neuronal morphology/apoptosis, respectively. Protein expression of Beclin-1, LC3 and Aβ1-40 was examined.
Results In the MWM test, the AD+EA group showed an improvement in parameters consistent with improved learning/memory compared to untreated AD rats, and 3-MA attenuated these effects. EA mitigated cellular apoptosis resulting from Aβ infusion in the CA1 region and enhanced LC3II/LC3I ratios and Beclin-1 expression. Numerous autophagosome precursors and enlarged autophagosomes were observed by TEM in the hippocampi of EA-treated rats. Reduced Aβ levels, and co-localisation of Aβ and LC3II, were observed following EA treatment by immunofluorescence staining. EA+3-MA treated rats had much higher TUNEL-positive neurons, lower LC3II/LC3I ratios and Beclin-1 expression, and elevated Aβ levels compared with EA alone.
Conclusions EA reduces neuronal apoptosis, enhances degradation of Aβ, and improves learning/memory in AD rats by upregulating the autophagy pathway.
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H-dG, JZ, contributed equally.
Contributors H-dG, JZ, J-xT, F-fM, Z-hY, and JlC performed the experiment. Y-wX, X-jH, L-sZ and D-yZ participated in the discussion and helped with the experiment. JZ, L-sZ and G-hC analysed the data. H-dG, S-jS, L-sZ and G-hC designed the study protocol and prepared the manuscript. All the authors have read and approved the final manuscript.
Funding Scientific and Technological Developing Scheme of Hangzhou (20130633B33), Zhejiang Provincial Foundation of National Science (LY13H160030), Shanghai Municipal Education Commission Program (2013JW03), Young University Teachers Training Subsidy Scheme of Shanghai (shzy015), National Natural Science Foundation of China (31400838, 81102670, and 81373754).
Competing interests None declared.
Ethics approval This study was prospectively approved by the animal ethics committee of Shanghai University of TCM and the Animal Research Committee of Shanghai, and was conducted in accordance with guidelines for animal welfare equivalent to the National Research Council’s ‘Guide for the Care and Use of Laboratory Animals’.
Provenance and peer review Not commissioned; externally peer reviewed.
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