The Effects Of Behavior Training On The Function Of Learning And Memory, And The Expression Of NR2B Around The Infarcted Focus As Well As In The Cortex Of Temporal Lobe In Rats With Hippocampal Infarction

Cerebral ischemia, as a common disease of the central nervous system (CNS), seriously harms people's health. In these patients with cerebral ischemia, mainly clinical manifestations are impairment of motor, sensory perception, especially the impairment of the ability of learning and memory, which is the most common and lasts a long time. Large amounts of experimentation and clinical research indicate that the CNS of adult animals after CNS injury is plastic and recoverable, structurally and functionally, which makes it possible for them to rehabilitate after CNS injury. CNS plasticity is reflected on many levels and in many taches, both on synaptic and neuron levels, pathway levels and on cerebral cortex level, which depends on the synchronic activation of many neurons necessary for any activity to be performed and the involvement of many nervous pathways and high central nerves. The rehabilitative training is equally important in the early, middle and advanced phases of CNS injury. It is by interacting with other people and his or her environment that the patient trains and practices his or her prompt andappropriate reactions to outside stimulants to adapt to the new environment and pick up his or her skills and abilities to learn, live and work. It is a process. Unless the injury is extremely mild, the self-recovery of the CNS is invariably limited. Only by rehabilitative trainig of the functions and by exercise can the recovery and the ability of the patient to adapt to the environment and to live independently be improved. Nevertheless, the fundamental of all these, the mechanism involved, remains unanswered.Hippocampus, a vital structure of closely related to learning and memory of CNS, often is vulnerable after global ischemia. In addition, hippocampus has high plasticity, which is the foundation of learning and memory ability. Photochemical induction method is generally used in the preparation of cerebral thrombosis model recently. Our lab had made the model of cortex infarction by the chlorophyll and He-Ne laser in the previous study and Yang wenqing et al also had made the model of middle cerebral artery(MCA) infarction by the self-made cold light source combined with rose bengal. And these models had been proved similar with the human cerebral thrombosis in the process of infarction. Single hippocampus infarction prepared by photochemical induction method has never been reported.From the past research, we know that NMDA-receptor is the key point to the learning and memory of CNS and is regarded as the capital regulator of synaptic plasticity and LTP of neurons in the hippocampus and cortex. Further more, NR2B subunit is critical to the structure and function of NMDA-receptor and also plays a very important role in the regulation of LTP. According to the research of NR2B gene, a new point was proposed that NR2B gene was the memory gene. Now, NR2B has been the focus of the research on learning and memory.The present study is a probe into the relationship between behavior training and CNS plasticity by means of establishing the model of photochemically induced hippocampal infarction in the rats and observing the effects of behavior training on the function of learning and memory and the expression of NR2B in the cortex of temporal lobe and hippocampus of cerebral infarcted rats in an attempt to contribute theoretically to the clinical rehabilitation therapy of cerebral stroke. The experiment consists of four parts.1. A model of photochemically induced unilateral hippocampal infarction in the ratsIn this experiment, the hippocampus infarction models of rats were made by photochemical induction method: the left hippocampus was irradiated by cold light source after intravenous injection of photosensitizer rose bengal. 3 days later, the infarct size, neuroethology and histopathology were detected. The results showed that the infarct volume had the linear correlation with concentration of rose bengal. However, in order to produce the infarction, the rose bengal concentration must be above 50mg/Kg. At the same time, in the unilateral hippocampal infarction models, we found that the impairment of neuroethology was not obvious.2. Establishment of photochemically induced bilateral hippocampal infarction in the rats30 SD rats were divided into two groups at random: photochemically-treated group and normal group. A photochemical-induced infarction was produced by tail vein injection of rose bengal (70mg/kg) and by immediate cold light irradiation (0.37W/cm~2) of bilateral hippocampus. 3 days later the changes in neuroethology and histopathology were observed. Results: Cerebral infarctionswere induced by 70mg/kg rose bengal combined with cold light irradiation. The sizes of infarction in bilateral hippocampus were stable, and changes in neuroethology and histopathology were pronounced.3. The effect of behavior training on the function of learning and memory in rats with bilateral hippocampal infarction30 SD rats were randomized into two groups: the behavior training(BT) group and the immobilization(IM) group 3 days after the rat model of bilateral hippocampal infarction had been immobilized, with 15 rats in each group. The BT groups were forced to practice in water maze; the IM groups were confined to barrel-shaped net cages and fed food and water from the head of the cage. The ability of learning and memory was tested at 3 days before infarction, 3 days after infarction, 7 days, 14 days and 21 days after behavior training. The results showed that the ability of learning and memory was decreased after bilateral hippocampal infarction (P<0.01); in BT group, recovery of the ability of learning and memory was faster than in IM group at different points of time.4. The effect of behavior training on the expression of NR2B around the infarcted focus and in the cortex of temporal lobe in rats with bilateral hippocampal infarction54 SD rats were randomized into fore-training, 7d, 14d, 21d training groups, fore-immobilization, 7d, 14d, 21d immobilization groups and control group. Behavior training and immobilization were performed at 3d after the infarction. The expression of NR2B around the infarcted focus and in the cortex of temporal lobe was detected at different points of time. The results showed that the expression of NR2B is abundant in the normal hippocampus and cortex of temporal lobe of rats. The expression of NR2B decreased after infarction and...