| Acute hypoxic-ischemic cerebrovascular disease is worldwide and frequently-occurring disease at present.It threatens humans's health with its high morbidity and mortality rate. Study shows that the brain is sensitive extremely to hypoxic-ischemic,and it can cause irreversible damage in this condition. At the early ischemic stage,ischemic penumbra around the ischemic core, which survival time is limited.Because the ischemic penumbra cerebral volume accounted for the entire half of the cerebral infarction, if not taken into neural protective measures,it will change into irreversible cerebral infarction. It is a key to save the penumbra brain tissue. At present, clinical data shows that the decompressive craniectomy in neurosurgery can reduce the volume of cerebral infarction, protect the penumbra brain tissue and improve nerve function,reduce mortality.But its specific mechanisms are not yet clear. Therefore, we attempt to clarify its molecular mechanism by animal experiment as well as explore whether decompressive craniectomy is better treatment for acute ischemic cerebrovascular disease.Objective: This experimental study is for operating decompressive craniectomy for rats with permanent middle cerebral artery occlusion(MCAO), observing the histopthology and electron ultrastrmicrostracture of the rat's brain tissues, detecting the expression of NF-κB and the neuronal apoptosis,exploring protection mechanism of the brain after decompressive craniectomy.Methods:1 Experimental animal's selection and grouping: A total of 75 healthy adult Sprague-Dawley rats,weighting250g ~ 280g, randomly divided into 3 groups: Cerebral ischemia group (IS)(n=25);Cerebral ischemia and decompressive craniectomy group (IS+DC) (n=25); Decompressive craniectomy group (DC) (n=25); Each group according to different time after infarction (6h, 12h, 24h, 72h, 7d) divided into five sub-groups .2 Model Preparation: IS group: Prepare the rat model with middle cerebral artery occlusion (MCAO) by Zea Longa's method.IS+DC group: After the success of MCAO rats at 6h, 12h, 24h, 72h, 7d,operating decompressive craniectomy, DC group : operating only decompressive craniectomy at 6h, 12h, 24h, 72h, 7d.3 Animals in each group were killed at different preset time(6h, 12h, 24h, 72h, 7d). The brains were collected to observe the range of cerebral infarction by TTC staining ,and to observe the histopathological change by HE staining, and to observe the changes of ultrastructure by electronic microscope.4 The brain tissues were collected to detect the changes of NF-κB expression by Immunohistochemistry.Under the microscope, taking 3-5 visual field randomly in the infarct region to photograph.To observe the positive staining in every brain region by microscope,and to measure the MOD of positive area inevery field of vision by'Image-Pro Plus 5.0'image analytical system.5 Detecting the change of NF-κBp65mRNA by Semi-quantitative of RT-PCR. Using the electrophoresis and semi-quantitative analysis, taking the amplification product electrophoresis,scanning by using computer software, determinating the gray ,comparing the relative amount of PCR product.6 Detecting the changes of neuron cell apoptosis by TUNEL method. Taken 4 vision fields randomly on the round of the infarct lesion.Counting positive cells by using High-power microscope (400 times). The results were calculated by statistical treatment with SPSS15.0 software.Results:1 The rat model with middle cerebral artery occlusion(MCAO) was duplicated successfully. All of the rats appeared hemiparalysis in different extent after infarction,such as the body clinism, walk rotate and so on.2 It was found that lots of nerve cells in center of the infarction were necrosis obviously 24 hours after the infarction through observing the changes of histopathology structure and ultrastructure by electronic microscope. With the time extend, the degree of necrosis aggravated and the necrosis was inconvertibility. The nerve cells in the ischemic penumbra area were necrosis partly and could be repaired and saved.But operating decompressive craniectomy,the injury of the brain was relieved.3 The expression of NF-κB can be found in neuronal cells, glial cells, vascular endothelial cells .In ischemia 6h : the amount of NF-κB expression is small in IS Group. In ischemia 12h:the expression of NF-κB was enhanced continue.In ischemia 24h : the expression of NF-κB was enhanced continue. In ischemia 48h: it reached a peak. Since 72h , it declining gradually. In ischemia 24h: the expression of NF-κB were reduced and to a lower level. Compared with the IS group, at different time, in IS+DC group the expression of NF-κB was reduced significantly. The expression of NF-κB is scare in DC group at different time .4 Compared with the IS group, at different time, in IS+DC group the relative amount of PCRof NF-κBp65mRNA RT-PCR was reduced significantly. The expression of NF-κBp65mRNA is scare in DC group.5 There is a large number of the cells apoptosis in the neurons and the glial cells and some vascular endothelial cells of the IS group. Compared with IS group, the number of apoptotic cells of IS+DC group reduced obviously (P <0.05). the The number of cells apoptosis is less in DC group.Conclusion: 1 The middle cerebral artery occlusion (MCAO) model was duplicated successfully using intraluminal suture and confirmed the success by neurology score, TTC staining, histological observation through HE staining and ultramicrostructure observation through electron microscope.2 The expression of NF-κB and NF-κBp65mRNA RT-PCR the relative amount of PCR product at each time was significantly lower than the IS group(P<0.05).3 Compared with the number of cell apoptosis of IS group, IS+DC group was reduced obviously. The distribution of the cell apoptosis is the same as the expressionof NF-κB .4 Decompressive Craniectomy can protect brain of penumbra by reducing the expression of NF-κB in the ischemic penumbra and reducing cell apoptosis.
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