Abstract: Objective To observe the effect of electroacupuncture with different frequencies on learning and memory ability, synaptic morphology and synaptic density in the hippocampus of Alzheimer's disease rats. Methods Forty-eight healthyWistar rats were randomly divided into normal group, sham operation group, model group, 2 Hz, 30 Hz and 50 Hz electroacupuncture groups with 8 cases in each group. The Alzheimer's disease model was established by injecting Aβ1-42 into two sides of lateral cerebral ventricle. The sham operation group was injected with normal saline instead. The electroacupuncture groups received electroacupuncture at Baihui (DU20) and Shenshu (BL23) acupoints. The learning and memory ability was evaluated with Morris water maze test, and the morphology and density of synapse were observed by electron microscope. Results Compared with the model group, the latency was shorter, the time of crossing the platform was shorter and the number of crossing the platform was more in the electroacupuncture groups (P<0.01), especially in the 50 Hz electroacupuncture group (P<0.01). The number of synapse and the synaptic density were more in the electroacupuncture groups than in the model group (P< 0.01), especially in the 50 Hz electroacupuncture group (P<0.01). Conclusion Electroacupuncture could improve learning and memory ability and increase synaptic density in rats with Alzheimer's disease, especially with high frequency.

Key words: Alzheimer's disease, electroacupuncture, frequency, learning and memory ability, synaptic density, rats