Objective:To observe the influence of electroacupuncture(EA)on mitochondrial ultrastructure and mitochondrial enzymatic activity in hippocampus of senescence accelerated mouse/prone 8(SAMP 8)so as to explore its underlying mechanism in the treatment of Alzheimer's Disease(AD).Methods:Twenty-four SAMP 8 mice were randomly and uniformly divided into model group and EA group and other 12 SAMR1 mice were used as control group.EA(2-100 Hz

2-4 V)was applied to"Baihui"(GV 20)and "Yongquan"(KI 1)for 30 min.Changes of learning and memory ability were measured by Morris water maze test.The ultrastructure of hippocampal mitochondria was observed by using transmission electronic microscope.The activities of cytochrome C oxidase(COX)in hippocampal mitochondria were detected by spectrophotometric method.Results:In comparison with control group

the average escape latencies of model group were significantly longer from the 1st day to the 5th day in swimming test(P<0.01)

while in comparison with model group

the escape latencies of EA group at the corresponding test day were markedly shorter(P<0.05

0.01)

despite being still obviously longer than those of control group.The ultrastructure of most mitochondria of EA group was basically normal

and the mitochondrial cristae were line up in order and presented mild swelling.Volume density and area density of mitochondria and COX activity of model group were significantly lower than those of control group

and these 3 indexes of EA group were significantly higher than those of model group(P<0.05

0.01).Conclusion:EA can improve AD rat's hippocampal mitochondrial structure and increase mitochondrial COX activity

which may contribute to its effect in improving the rat's learning and memory ability.