| Part 1 MRI and TTC staining in assessing the cerebral infarctvolume in ratsObjective: Acute cerebral infarct model were made in rats, two methods, the T2-weighed magnetic resonance imaging(MRI) and rutine 2,3,5-triphenyltetrazolium chloride(TTC) staining were used in assessing infarct volume.Methods: We made focal left middle cerebral artery occlusion model with fishing thread in rats, sequential T2-weighed MRI and TTC studies were performed at 6,12,and 24 hours after the onset of occlusion. Then we calculated the ratio of the infarct volume to the contralateral hemisphere volume respectively.Results: By the 6h after MCAO, T2-weighed MRI and TTC staining changes were localized the cortex, by the 12h and 24h the infarct volume enlarged. The spread of MRI changes were consistent with the injury with the TTC staining. There were highly significant correlations between lesion size determined by MRI and histopathology. The degree of damage observed in the T2-weighted MRI, as well as the size of TTC-stained tissue were, in turn, highly correlated with the scores of neurological deficiencies..Conclusion: Both T2-weighed MRI and TTC staining could be used to delineate areas of acute ischemic stroke in experimental models, T2-weighed MRI is more reproducible and faster and simpler than routine TTC staining , It could be used to evaluate infarct volume in vivo.Part 2 Expression of VEGF and its receptor and the relationship with microvessel density in rats of cerebral ischemiaObjective.To clarify the chronological expession of VEGFand its receptor(FLK-l) in experimental cerebral infarction and try to investigate the correlation between angiogenisis and induction of VEGF and FLK-1.Methods: With the use of a focal permanent middle cerebral artery occlusion model(MCAO) in rats, VEGF mRNA and VEGF/FLK-1 protein expression were identified by Reverse Transcription- polymerase chain reaction (RT-PCR) and immunohistochemistry respectively. Microvessels were marked by immunohistochemistry with anti-laminin antibody.These indexes were analyzed at different time courses from 3h to 7d using semi-quantitative methods.Results: VEGF and FLK-1 were upregulated commencing 3h after onset of MCAO,reached a peak after 24h,and remained expressed at low levels until 3d after MCAO,there was no expession at 7d.The numbers of microvessels began to increase at 3d after onset of MCAO,and continue to heighten at 7d.Conclusiorr.The correlation between the induction of angiogenesis with VEGF/FLK-1 expression suggests that the ischemic upregulation of VEGF and FLK-1 represents a compensatory physiological response of the brain to resist ischemic injury.The endogeneous angiogenesis is the root of recovering cerebral blood and the basis of exogenous treatment.Part 3 Protective effects of intracortex infusion VEGF on focalcerebral ischemia in ratsObjective:To study the angiogenic and neuroprotective effects of chronic intracortex infusion VEGF 164 on ischemic rat brain tissue,and to investigate the effects of different-dose VEGFon the rats of 7d and 6h after left middle cerebralartery occlusion (MCAO).Methods.Part 1: Rats underwent 7-day left MCAO,recombinant rat VEGF 164 was infused into the left cortex of rats at a rate of 0.5ul/min for 20 min,one time per day for three days, at concentrations of 10ug/ml,20 ug/ml,30 ug/ml,control animals received PBS only.Infarction volume was shown with T2-weighed MRI,neurological deficit scorces were determined with a 0-5 grade scale.Vessels were indentified in laminin immunohistochemical analyses.Brain edema was assessed with brain water content measurements .In addition,TUNEL staining was examined to investigate the effect of VEGF administration on neuronal cellular apoptisis.Transmission electron microscope was used to observe ultrastructure of cerebral tissue and to find hyper-proliferation cells.Part 2: Rats underwent 6-hour left MCAO, VEGF 164 was infused into the left cortex of rats at a rate of 0.5ul/min for 20 min, at concentrations of 30 ug/ml,the indexes we observed...
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