| BackgroundThe dysfunction of nervous system caused by acute cerebral infarction has been a major medical problems. It is newly discovered that Nogo-A is the most intense axonal regeneration inhibitory factor, Nogo-A conducts the inhibitory signals through the combination of receptor NgR to obstruct nerve repair and regeneration.It is the important reasons for the poor dysfunction of nervous system.Electroacupuncture is one of the effective treatments for cerebral infarction, but the mechanism still is not clear. Our previous research suggests that the electroacupuncture can protect the brain tissue against cerebral ischemia injury by regulating the expression of nurocan, but whether it has influence on the expression of Nogo-A or not?It has not seen at home and abroad, is worth discussing.ObjectivesObserving the influence of electroacupuncture on the expression of Nogo-A and the ultramorphology of central nervous system in cortex at different time points in rats with cerebral ischemia for 2h and then reperfusion. To disscuss the mechanism of curing ischemic stroke and promoting the recovery of nerve function by electroacupuncture from the new aspects of the expression of axonal regeneration inhibitory factor. It may provide a new theory and method for the clinical application of electroacupuncture.Method145 male Sprague Dawley (SD)-rats(three months, weight(240±40g) were randomly divided into IR group(105 rats),shamp group(30 rats) and blank group(10 rats). The rats in IR group were duplicated MCAO(middle cerebral artery occlusion) model by modified ZeaLonga method. And then they were randomly divided into electroacupuncture group(35 rats),model group(35 rats) and false electroacupuncture group(35 rats). Among them, positioning"Baihui"(DU20)and "Dazhui"(DU14)points of rats in electroacupuncture group 30min once a day for 28 days. In false electroacupuncture group, positioning the points one inch from "Baihui"(DU20)and "Dazhui"(DU14) 30min once a day for 28 days. In shamp group, only the skin was incised, the carotid artery was sutured after onset of exposure. Observing the changes of brain infarction area by TTC 7d after operation, the changes of ultramorphology by transmission electron microscope and the expression of Nogo-A by immunohistochemical in bilateral cortexs among electroacupuncture group, model group and false electroacupuncture group Id,7d,28d after operation. Observing the influence of electroacupuncture on aboving indexes and analysis. All data was calculated by software SPSS13.0, using repetitive measurement and analysis of variance.Results①neuroethology score:the electro-acupuncture group rat neuroethology score after I/R1,7days, respectively, compared with the same period of the model group and false electroacupuncture group, there was no significant difference (P>0.05); 28days of I/R, the electro-acupuncture was significant difference (P<0.05) in comparison with the model group and false electroacupuncture group;compared with the same period of the model group and the neuroethology score of sham acupuncture point group, there was no significant difference (P>0.05)②the changes of cerebral infarction volumeOn 7th after cerebral ischemia-reperfusion, the injured brain hemisphere volume increased significantly, the gyrus became flat and sulcus became shallow. The brain tissue was pale. In right brain hemisphere, gyrus and sulcus were normal, the brain tissue was pale red. The brain structure was distinct, clearly visible.TTC stain showed that the injured brain hemisphere appeared focal pale in cortical and subcortical infarction areas. In right brain hemisphere, it was rose red. Compared with the model group and shamp group, the cerebral infarction volume decreased significantly, and there was statistical difference(P<0.05) in electroacupuncture group.There was no statistical difference(P>0.05) among model group, shamp group and electroacupuncture group.③the changes of ultramorphologyThe cortex of affected side Using transmission electron microscope, the cerebral cortex structure were distinct and with normal cells form between blank group and shamp group. Neurons without edema, nuclei nucleoli was obvious and nuclear membrane was integrity, endoplasmic reticulum, mitochondria and other cells were clearly visible. The form and structure of oligodendrocytes were normal, capillaries were open, the vessel wall was compact connection, and endothelial cells were complete, no edema.Among electroacupuncture group, model group and false electroacupuncture group,it appeared different levels of pathological changes such as the ischemic areas in brain cortex were edema, neurons and oligodendrocytes were degeneration and vessels were collapse and so on at different time points. The changes were the most serious on 7th after MCAO. On 28th, the brain ischemic injury gradually restored, neurons swelling disappeared, oligodendrocytes were reactive hyperplasia and capillaries regenerated. Compared with model group and false electroacupuncture group, The injury of neurons, oligodendrocytes, capillaries and other ultramorphology in cerebral ischemia area were relatively easer than that in electroacupuncture group.The cortex of contralateral sideUsing transmission electron microscope, the cerebral cortex structure were distinct and with normal cells form between blank group and shamp group. Neurons without edema, nuclei nucleoli was obvious and nuclear membrane was integrity, endoplasmic reticulum, mitochondria and other cells clearly were visible.The form and structure of oligodendrocytes were normal, capillaries were open, the vessel wall was compact connection, and endothelial cells were complete, no edema.Among electroacupuncture group, model group and false electroacupuncture group, it appeared different levels of pathological changes such as the ischemic areas in brain cortex were edema, there was mild chromatolysis, the endothelial cells of capillaries were edema and the vessel lumen was stenosis at different time points. The changes were the most serious on 7th and significantly decreased on 28th after MCAO. The aboving pathological changes were all easer than that in the affected side at the same time, and did not cause the the dysfunction of nervous system. Compared with model group and false electroacupuncture group, The injury of neurons, oligodendrocytes, capillaries and other ultramorphology in cerebral ischemia area were relatively easer than that in electroacupuncture group.④The expression of Nogo-A positive cellsThe cortex of affected sideThe expression of Nogo-A positive cells in cortex were normal, mainly expressed in oligodendrocytes cytoplasm in balank group and shamp group, and there was no statistical difference(P>0.05). In model group, the expression of Nogo-A positive cells increased on lth, significantly high on 7th, and then decreased on 28th after MCAO. But it wes still higher than normal level. Compared with the shamp group at the same time, there was statistical difference(P<0.05) in the expression of Nogo-A positive cells. On lth,7th,28th after MCAO, compared with the model group and false electroacupuncture group at the ame time, the expression of Nogo-A positive cells in electroacupuncture group was lower, and there was statistical difference(P<0.05). But there was no statistical difference(P>0.05) between the false electroacupuncture group and model group.The cortex of contralateral sideThe expression of Nogo-A positive cells in cortex were normal, mainly expressed in oligodendrocytes cytoplasm in balank group and shamp group, and there was no statistical difference(P>0.05).In model group, the expression of Nogo-A positive cells increased significantly on 7th, and then decreased on 28th after MCAO. But it was still higher than normal level. The expression of Nogo-A positive cells in the contralateral side was lower than that in the affected side, and there was statistical difference(P< 0.05). On 1th,7th,28th after MCAO, compared with the model group and false electroacupuncture group at the ame time, the expression of Nogo-A positive cells in electroacupuncture group was lower, and there was statistical difference(P<0.05). But there was no statistical difference (P>0.05) between the false electroacupuncture group and model group.Conclusion①Nogo-A participated in control the pathological process of neurite regeneration, after cerebral ischemia injury.②Electroacupuncture can reduce the damage of brain tissue in rats with cerebral ischemia-reperfusion. It probably has correlation with decreasing the neuroethology score of rats, reducing the damaged ultramorphology of brain tissue, narrowing cerebral infarction areas, downregulating the expression of Nogo-A and inducing the reshape of nervous system.It would provide certain experimental basis on the mechanism research for the electroacupuncture curing ischemic stroke and promoting the recovery of nerve function.
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