Changes Of Cerebral Hemodynamics, BBB Permeability And VEGF Expression In Chronic Hypoperfusion In Rats

Objective To study the dynamic changes of cerebral microcirculation in chronic hypoperfusion and normal perfusion restoration process. Method Chronic hypoperfusion was induced by an end-to-end anastomosis between the right carotid artery and the right external jugular vein on 16 Wistar male rats. The animals were divided into two groups:group A(n=6)(the carotid artery occlusion only) and group B(n=10). Local cerebral blood flow (lCBF)and Local cerebral blood volume (1CBV) at 25 locations were assessed by a modern laser Doppler scanning technique at 4 time points before and after the fistula. Regional cerebral blood flow( rCBF) and regional cerebral blood volume (rCBV )were measured by the median of 25 data. Results In the bilateral hemisphere of group A and the left hemisphere of group B, both of rCBF and rCBV didn' t change. However, in the right hemisphere rCBV significantly increased 2 weeks after the bypass but recovered after clipping of thefistula(P<0. 05), and rCBF significantly decreased 2 weeks after the bypass but recovered after clipping of the fistula (P<0. 05). Conclusion The rat model of carotid-jugular arteriovenous fistula is clinically relevant and useful for studying the pathophysiology of chronic venous hypertension. Venous ischemia is a reversible condition which can be improved by appropriate early-stage treatment.Part TwoEstablization of the Rat Dural Arteriovenous Fistula Model and VEGF Expression in the Modelobjective To develop the rat dural arteriovenous fistula model ,study the cause of dural arteriovenous fistula (dAVF), and investigate the role of vascular endothelial growth factor (VEGF) in dAVF formation. Methods An improved Herman' s method was performed on 36 Wistar male rats, which were divided into group A(n=12), group B(n=12) and two control group(n=6). The rat dAVF model was developed by creating a carotid-jugular fistula as well as a superior sagittal sinus ligation. The expression of VEGF was observed in dural vessels with imraunohistochemistry 2 weeks later and the cerebral angiography(CAG) was studied 90 days later. Results Significant changes of VEGF expression and CAG were not observed in control groups. 58% rats (7/12) in group A were positive of VEGF expression, 75%(9/12) showed VEGF positive in the cerebralcortex and basal nuclei, and 41% rats(5/12) of group B showed dAVF in the face vein and/or transverse sinus. Conclusion VEGF expression may play an important role in the angiogenesis and dAVF under chronic intracranial venous hypertension in the rat.The Permeability Changes of Blood-brain Barrier during Reperfusion after Chronic Hypoperfusional Cerebral Ischemia in RatsObjective To quantificationally analyze the permeability of blood-brain barrier (BBB) with the hypersensitive fluorescent methods during reperfusion after chronic hypoperfusional cerebral ischemia. Methods The male Wistar rats(n=40) were divided into 3 groups: contrast group(n=5), no reperfusion group (n=5) and reperfusion group (n=30). The end-to-end anastomosis of the right common carotid artery and the right external jugular vein was performed, the superior sagittal sinus was ligated and the the rat model of carotid-jugular arteriovenous fistula was established in the reperfusion group and the no reperfusion group. Only the right common carotid artery was ligated in contrast group.2 weeks later, The Evans Blue(EB) was injectted into the caudal vein at 2 hours before the end of experiment in every group. The anastomosis locus was blocked to form the reperfusion after the ischemia in the reperfusion group. The EB fluorescence quantitative method was used to observe the permeability of BBB at 2h after EB injection in contrast group and no reperfusion group and at 2h, 3h, 9h, 24h, 48h...