[Effect of electroacupuncture on learning-memory ability of vascular dementia rats with concomitant hypertension and hyperlipemia]

Abstract

Objective: To observe the effect of electroacupuncture (EA) of acupoint recipe for "dredging Governor-Meridian, regulating vitality and strengthening the kidney" on learning-memory ability and pathological changes of cerebral minute blood vessels and hippocampal structure in hypertension-hyperlipmia-vascular dementia (HH-VD) rats.

Methods: Forty SD rats were randomly divided into sham-operation (sham) group (n=8), EA-I group [n=8, EA of "Baihui" (GV 20), "Dazhui" (GV 14), "Pishu" (BL 20) and "Shenshu" (BL 23), 80 Hz, 1 mA, 20 min/day, 15 days], EA-II group (n=8, EA of nonpoints, 5 mm lateral to the abovementioned acupoints), medication group (n=8, intragastric perfusion of Nimotong, 0.6 mg/mL, 20 mL/kg, 15 days), model group (n=8). HH-VD model was established by feeding the rat with high fat forage and by occlusion of the left renal artery and carotid artery. The animals' learning-memory ability was detected by Y-maze test, the synaptic structure of the hippocampal CA 1 region, and the pathological change of the cerebral cortex were observed by electronic microscope and light microscope, respectively.

Results: After modeling, the blood pressure, serum total cholesterol and triglyceride (TG) levels, and the error number (EN), total reaction time (TRT) and standard number (SN, number of paw-electric-stroke for reaching correct reactions) of Y maze test increased significantly in comparison with sham group (P<0.05). After EA, the EN, TRT and SN of EA-I , EA-II and medication groups decreased significantly in comparison with model group (P<0.01), suggesting a striking improvement of the learning-memory ability after the treatment, and the EN, TRT and SN of EA-I group and medication group were significantly lower than those of EA-II group (P<0.05). Under electronic microscope, the number of synapses in hippocampal CA 1 area of HH-VD model rats reduced obviously, its postsynaptic density (PSD) was lighter, and the synaptic vesicles were fewer. Whereas in comparison with EA-II and medication groups, the synaptic number and density in EA-I group were more and bigger, and the width, length and color of PSD increased clearly. The synaptic number of EA-II group was relatively smaller compared with the other two treatment groups. Under light microscope, the vascular walls of the cerebral minute and small arteries of model group were obviously thickened and their lumina narrowed. While in EA-I group, these pathological changes were mild. In medication group the thickening of vascular walls of partial cerebral minute and small arteries were also seen.

Conclusion: EA of acupoint recipe for "dredging Governor-Meridian, regulating vitality and strengthening the kidney" can improve pathological changes of the synaptic structure of hippocampal CA 1 region and the vascular walls of cerebral minute and small arteries, which may contribute to its function in improving the learning-memory ability in HH-VD rats.