Effects Of Hyperlipidemia On Expression Of VEGF In Rats Brain With Chronic Cerebral Ischemia

Cerebral vascular disease is one of three lethal causes to human being with higher incidence,mortality and mutilation rate. Ischemic cerebral vascular disease accounts for 80% .Now,we have known much about the mechanism in focal cerebral ischemia reperfusion injury,but there is no uniform conclusion on chronic cerebral ischemia. Chronic cerebral ischemia is a common pathological status in nervous system diseases,it accompanied with many cerebrovascular diseases, such as arteriosclerosis, vascular dementia(VD), Alzheimer's disease (AD),arteriovenous malformation. Cognitive impairment is the primary clinical symptom in earlier period of chronic cerebral ischemia, and then develop to the permanent neural impairment gradually. Vascular endothelial growth factor (VEGF) is multifunctional. VEGF and VEGF receptor increase in the anoxemic brain , promote the formation of lateral vessels in penumbra,protect neuron direct or indirectly ,and that decrease infarct volume,reduces ischemic neuronal apoptosis,promotes neural stem cells proliferation,migration and differentiation and improves nerve functions.Hyperlipemia ,especially low density lipoprotein(LDL) raising up ,is a main dangerous factor to cerebral ischemia. Some researches indicate that VEGF has a lower expression in the blood circulation with hyperlipemia.It is harmful to the recovery of vascular endothelial function.Does hyperlipemia have same effects on VEGF in brain?We still need more studies on it. Objective:Establish animal model of chronic cerebral ischemia and hyperlipemia to observe changes of learning and memory abilities,to research the expression of VEGF after chronic cerebral ischemia in hyperlipidemic rat brain.Mathods:Divided male wistar rats into four groups.Permanent occlusion of bilateral common carotid arteries (2VO) was used to produce the chronic cerebral ischemia models.Animal fatty feeds to the hyperlipemic groups. To determine the ability of the learning and memory after the Morris water maze task training and the change of pathobiology through HE staining,the expression of VEGF in hippocampal area of rats after 2VO by immunohistochemistry.Results:In the Morris water maze task, rats with common carotid ligation displayed a learning and memory deficit, but the impairment was more severe in experimental + hyperlipemic group.Pathological changes: The degeneration, necrosis and detachment of neuron in hippocampus could be seen in the rats besides the contral group, the longer the ischemic time, the worse neurological damages. Compared with experimental group, experimental + hyperlipemic group damaged worse. Immunohistochemistry: We could find VEGF positive cells of hippocampal area both in experimental group and experimental + hyperlipemic group.They express mainly on neurons in the earlier time,as time extended,it diverses to the vascular endothelial cells. Conclusions:1. By permanent internal carotid ligation could establish the animal model of chronic cerebral ischemia successfully,and impairs the ability of rats'spatial learning and memory, hyperlipemia may aggravate the damages.2. Chronic cerebral ischemia causes pathological damages to the brain tissues, leads to the degeneration, detachment and loss of neuron,as time extended,the damages became worse.3.The expression of VEGF in hippocampal area increased following chronic cerebral ischemia,it express mainly in neurons during earlier period, as time extended, it diverses to the Vascular endothelial cells.