Electroacupuncture improves memory and protects neurons by regulation of the autophagy pathway in a rat model of Alzheimer's disease

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 beta-amyloid (A beta) clearance. We hypothesised that electroacupuncture (EA) treatment of AD involves the autophagy pathway in rats. Methods We injected 2 mu l A beta(1-40) 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 A beta 1-40 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 A beta 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 A beta levels, and co-localisation of A beta 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 A beta levels compared with EA alone. Conclusions EA reduces neuronal apoptosis, enhances degradation of A beta, and improves learning/memory in AD rats by upregulating the autophagy pathway.