Cognitive Impairment And Expression Of BDNF,TrKB Of Cortex And Hippocampus In Chronic Cerebral Ischemia Rats

Cerebral vascular disease is one of the most important diseases which are harm to our health. Ischemic cerebrov- ascular disease accounts for 70% cerebral vascular disease and possesses the specialty of high incidence of a disease, the disabled and recrudescence. Chronic cerebral ischemia is a common pathological status in nervous system,it accompanied with many cerebrovascular diseases, such as cerebral arteriosclerosis, Vascular dementia (VD), Alzheimer's disease (AD), Arteriovenous malformation. Cognitive impairment is the main clinical situation in earlier period of chronic cerebral ischemia, and then the permanent neural impairment. Its pathogenesis is different from acute cerebral ischemia. That endogenous BDNF and TrKB can inerease the plasticity of neuron of cortex and hippocampus and the activity of cholinergic system of the basal forebrain is thought to contribute to the improvement of cognitive function impairment.We adopted the permanent bilateral carotid arteries occlusion (2VO) in male Wistar rats to produce the chronic cerebral hypoperfusion. 72 rats were random divided into 3 groups after initial screening: blank control group, sham operation group, operation group. Morris water maze experiment tests the rats'memory change of each group of different time after 2VO (1,2,3,4 month). Brain samples with HE staining to observe the changes of nerve cell in each group rats'cortex and hippocampus iCA1 region with light microscopic methods; the changes of BDNF,TrKB by the immunohistochemical methods were observed. Explore brain damage of chronic cerebral hypoperfusion and protection of BDNF,TrKBthrough evaluating Behavioral changes and Pathological changes of therapy group and operation group at 1 months, 2 months, 3months and 4months after 2VO.The results are as follows:Behavioral changes: The rats with CCA occlusion performance showed their memory ability decreased from 1 month after operation, and with the time going, this situation become more serious.Pathological changes: With the time of the chronic cerebral ischemia going, the degenerating, necrosis and detachment of neuron could be seen in cortex and hippocampus CA1 region, even the pyramidal layer disappeared.The immunohistochemical changes: From the immunohistochemical slices, we saw there was a gradual decrease in number of BDNF,TrKB cortex and inhippocampus CA1 region after the occlusion of bilateral carotid arteries with the prolongation of ischemic time.From the whole experiment we can conclude:â‘ Permanent bilateral common carotid arteries occlusion to the rats can lead to chronic and permanent cognitive impairment.â‘¡Permanent bilateral common carotid arteries occlusion to the rats can lead to ischemic damage of the neuron and nerve fiberâ‘¢BDNF,TrKB can relieve the ischemic damage of neuron and nerve fiber caused by chronic ischemia.â‘£BDNF-TrKB can relieve the cognitive impairment caused by chronic ischemia.