INFLUENCE OF ELECTROACUPUNCTURE ON THE ULTRASTRUCTURE OF CA3 REGION OF THE HIPPOCAMPUS IN VD RATS

Objective: To observe the effect of electroacupuncture (EA) on learning and memory abilities and ultrastructure of synapses in CA3 region of the hippocampus in vascular dementia (VD) rats. Methods: A total of 32 SD rats were randomized into control (sham-operation, n=7), model (n=7), EA (n=9) and medication (n=9) groups. VD model was established by occlusion of the bilateral vertebral arteries (electrocoagulation) and bilateral common carotid arteries (occlusion for 5 min and reperfusion for 10 min , repeated the procedure for 3 times to induce global ischemia). EA ( 150 Hz , 1 mA ) was applied to “Baihui”(百会 GV 20), “Geshu”(膈俞 BL 17), “Pishu”(脾俞 BL 20) and “Shenshu”(肾俞 BL 23) for 20 min , once daily and continuously for 15 days. In medication group, the rats were fed with Nimotong (12 mg/kg), once daily and continuously for 15 days. Morris water maze method was used to test the animals' learning and memory abilities (latencies to find the hidden platform determined by place navigation trials, and latencies to cross on the location of the removed platform determined by spatial probe trials) after the treatment. Ultrastructural changes (numerical density, N_A,surface density, Sv and volume density, Vv) of Gray type 1 synapses in CA3 region of the hippocampus were observed by using transmission electronic microscope and automatic image analysis system. Results: 1) Place navigation test showed that in comparison with control group, the average escape latency of VD group was significantly longer (P0.01), while in comparison with VD group, the latencies of both EA and medication groups decreased significantly (P0.01). No significant difference was found between EA and medication groups in the escape latency (P0.05). 2) Spatial probe-test displayed that in comparison with control group, the times which the animals crossed the target platform in VD group decreased significantly (P0.01), while compared with VD group, those of both EA and medication groups increased considerably (P0.01). No significant differences were found between EA and medication groups in the times for rats to cross the target quadrant and among the 4 groups in the times for rats to cross the other quadrants. 3) Compared with control group, N_A, Sv, and Vv of VD group decreased significantly (P0.01), while in comparison with VD group, the 3 indexes of both EA and medication groups increased significantly (P0.01), no significant differences were found between EA and medication groups in these 3 indexes (P0.05). Conclusion: EA can restrain the loss of Gray type Ⅰsynapses in CA3 region of the hippocampus to improve learning and memory abilities in VD rats.