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Expressions of VEGF and bFGF after Focal Cerebral Ischemia-reperfusion in Diabetic Rats

Author: SunLeYu
Tutor: WangJianPing
School: Zhengzhou University
Course: Neurology
Keywords: Diabetes Ischemia/reperfusion VEGF bFGF
CLC: R743.3
Type: Master's thesis
Year: 2007
Downloads: 126
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Abstract

Backgrounds and ObjectiveStoke is the second most common cause of death. Previous studies indicated that diabetes melitus is an independent rist factor for stroke. Diabetes melitus is strongly related to early stroke progression and associated with poorer stroke outcome. Great attention has been paid for ischemic cerebral vascular disease. But currently treatment options for most type of stroke are not successful. The treatment of thrombolysis is the most promising method but yet have some defects which prevent it from being avidly performed. Therefore,to study the endoprotectic mechanism following ischemic stroke may become a new meathod to protect the neuron.Vascular endothelial growth factor(VEGF)and basic fibroblast growth factor (bFGF) are the two main members of neurotrophic. They play an important role in new blood vessel formation, neuron growing,maturing and synapsic forming. The expression of VEGF and bFGF in cerebral infarction after focal cerebral ischemia-reperfusion is not reported in diabetic rats.In the study we used STZ to induce diabetic rats. A middle cerebral artery occlusion (MACO) model was reproduced with SD rats. To calculate the infarct volume of brain. The expression of VEGF and bFGF in the penumbra area of the diabetes and normal group was measured with immunohistochemical method in different times after MACO (6,12, 24,48h).The difference was studied in comparison between the diabetes group and normal diabetes group. So we could offer some theorical grounds for ameliorate the clinical prognosis of stroke patients.Materials and Methods1.76 male healthy rats ,two months old ,weighing 280 to 310 grams. All the rats were divided into the sham group,diabetic groups and the normal control groups which were subdivided reperfusion 6h,12h,24h,48hgroups after 2h ischemia (n=10,10,6,6).2.Duplicateing the diabetic rats model by intraperitoneal injection streptozotocin. If the blood sugar higher or equal 16.7mmol/L manifested the success of model,then raised the rats for 6 to 7 weeks. We duplicated the ischemia/re-perfusion models accoding to the way of reports made by Zea-longa .The sham group were made the same operation except the nylon thread should not reach the internal cervical artery.3.After the models were made ,we did the nerve function mark by Zausinger,the rats got lower 1 marks or higher 3 marks were deserted.4.Executing the rat and extracting the brain tissue on 6h and 12h;probing the infarct volume by 2% 2,3,5-triphenytetrazolium chloride staining,Observing the positive expressions of VEGF and bFGF in the infarct area and ischemic penumbra by means of SP.5.The data was handled with SPSS10.0 statistic software. The difference of two groups was compared with t-test. The difference of many groups was compared with one-way analysis of variance and Newman-Keuls, significant level wasα=0.05. The experimental data was described by means±standard deviation.Results1.After the ischemic/reperfusion model was established,we gave marks on the rats about the nerve function impairment;Finding there are significant difference between the diabetic rats (2.13±0.71) and the normal ones(1.28±0.46).2. The TTC staining results of the rat’s brain :The brain tissues withoutinfarction were stained as red, The infarction zone could not be stained and appeared as white and the white zones distributed in accordance with the distribution of the medial cerebral artery; There was a larger white areas in diabetes group than in normal group after the same reperfusion time.3.Observing the results of pathological sections stained by HE: in the sham groups,the pathological changes were not remarkable. Compared with normal group,we found the lesions were more serious in diabetes group,which manifested the tissues become loose,the neurons’ nucleus atrophy and transfer,the endochylema become dispersed ,the staining become light,the inflammory cells around the infarct area increased remarkablely,the cell morphous altered.4.There were little expression of bFGF and no expression of VEGF in the sham group and the non-ischemic hemisphere in the brain tissue. The amount of the VEGF and bFGF expression began to increase since the 6h reperfusion post 2h ischemia,it reached peak in the 24h,then decrease rapaidly at 48h point;the positive expression in the normal ischemic/reperfusion rats was remarkable higher than that in the diabetic ones. in diabetes groups the most marked upregulation occurred in vacular endothelial cells, neurons and gliocytes in the infarct and the border zones. The positive expression in the border zones showed a moderately intense than infarctzone.Conclusions1 .There were significantly complicated larger infarction areas in the brain tissues after ischemia-reperfysion with diabetes than without it,The damagement signs of neural function after ischemia with DM was much more serious than that without DM.2.There were significantly lower expressions of VEGF and bFGFin the ischemic tissues after ischemia-reperfusion complicated with diabetes than without it, which was probably one of the reasons for the endoprotectic mechanism and the worse outcome incerebral ischemia complicated with DM.

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