| Objective:Stroke, as a common disease of the central nervous system (CNS),seriously harms people's health and claims high mortality rate and disability rate. 70-80% of survivors leave sequelaes of different degree,including motor dysfunction, sensibility dysfunction, cognitive dysfunction and so on, 40% of survivors can not take care of themselves. These not only take pain to the sufferer, but also take burden to their family and society. Nowadays, stroke rehabilitaion developes rapidly, active rehabilitative therapy for the survivors can help 90% of them restore their ability to walk and take care of themselves, and 30% do some light work again. However, without active rehabilitative therapy, the rates in the two above recoveries can reach only 60% and 5% respectively. In the animal experiments, there were irrefutably evidence indicated that: rats reared in enriched environment(EE) after MCAO recovered better than reared in standard environment. But how does it affect on the recovery of extremity function?Which factor in EE plays the main effect?What is the mechanism? All of these are not clear. It confined deeper development of rehabilitative effect. Therefore, in order to improve stroke survivors's living quality and help them go back to the society,to study the best environment intervention method after CNS injury, the more active component of enriched environment, and the recovery mechanisms of all kinds of dysfunction has aroused increasingly great attention. Large amounts of experimentation and clinical research indicate that CNS of adult animals after CNS injury is plastic. CNS plasticity is reflected on many levels and in many taches, both on synaptic and neuron levels, pathway levels and on cerebral cortex level. Neuroimaging reaserch on stroke indicated that CNS activity mode changed after stroke. Some reaserch showed that at cortical neuron and glial cells of peripheral cortex, local cortex leision could cause dendrite, axon growth branching and synapse increasing. What's more, spontaneous recovery was thought related with CNS plasticity. But the reasearch about the effect of exploratory and learning on peripherial cortex plasticity and hippocampus after stroke is seldom, and no reaserch is about bFGF and NG. In this case, on the basis of MCAO model, we randomly divided rats into sham group, control group, and exploratory and learning group. We observed ethology changes and the expression of bFGF,NG in the peri-ischemic cortex and hippocampus by Ethology tests and immunohistochemistry in attempt to study the mechanisms and effects of CNS structure plasticity after exploratory and learning intervention.Methods: 80 male Sprague-Dawley rats were adopted. After making the model of MCAO by electric coagulation successfully, they were randomly divided into exploratory and learning group(n=30, living in exploratory cages), control group(n=30, 5 as a group living in large standard cages).Other 20 rats didn't electric coagulat the middle cerebral artery, as sham group living in standard cage. 15 rats were chosen randomly from both the the groups for Berderson test,manual muscle test and balancing test at the 1st, 7th, 14th, 28th day after operation, and water maze test from 21st day after operation. At the 1st, 7th, 14th, 28th day after MCAO, 5 rats were randomly killed separately in learning group and control group. 5 rats in sham group were randomly killed separately at the 7th, 28th day after operation. The expression of bFGF, Ng in the peri-ischemic cortex and hippocampus were examined by using immunohistochemistry straining.Results: 1. After 24 hours of MCAO, severe impairment of function occurred in operated groups and there was no significant abnormal in sham group. 2. Berderson test: In 1-7 days after MCAO, there were no significant difference among the operated groups(P>0.05); In 14-28 days exploratory and learning group scored better than control group (P<0.05); 3. mesh exercise: In 1-7 days after MCAO, there were no significant difference among the operated groups(P>0.05); in 14-28 days,there were significant difference among the operated groups(P<0.05); 4. balancing test:In 1-7 days after MCAO, there were no significant difference among the operated groups(P>0.05); in 14-28 days,there were significant difference among the operated groups (P<0.05).3. Water maze test: It is thus clear that the latent phase of the operated groups were longer than the sham group since 21st to 25th day in the testing phase (P<0.05). Compared to the control group, the latent phase of learning group was shorter since 21st to 25th day in the testing phase (P<0.05). The latent phase of the operated groups decrease quickly in the first 3 days, then tended to stable since the 24th day, and maintained at a constancy level.The expression of bFGF in the peri-ischemia cortex: The expression of bFGF increased at 1 day after operetion in exploratory and learning group, there were significant difference between sham group and exploratory and learning group(P<0.01).The expression of bFGF in all operated group after MCAO 7th day was higher than sham group (P<0.01), and decreased with time.But at 28th day,the expression of bFGF of operatd group was higher than sham group(p<0.01).The expression of bFGF of exploratory and learning group was higher than control group and sham group from 1st week(P<0.01).The expression of Ng in the peri-ischemia cortex: In all operated group, the number of Ng labeled cells in the peri-ischemia cortex was lower than sham group at any time point. They had significant difference compared with sham group(P<0.01). In all operated group after opertation, the expression was increased gradually with time ,at 14th day the number of Ng labeled cells was highest. Then the expression decreased gradually.The Ng expression of exploratory and learning group was significantly higher than control group after 7th day(P<0.01).Conclusions:1. Model of MCAO was made successfully by occluding MCA from the olfactory tract ot lateral to the inferior cerebral vein with electric coagulation.2. Exploratory and learning could enhance the functional and memory recovery of local infarcted rats.3. bFGF can strongly stimulate and promote the growth and differentiation of neurocytes, put off the degeneration and aging of neurons, maintain the survival and normal functions of neurocytes and promote the repair of injured cells. Exploratory and learning promoted the expression of NF in the peri-ischemic cortex.4. Neurogranin(Ng) was involved in the mechanism of synaptic plasticity, including several path ways of protein signal transductionin the brain, long- term potentiation and long - term depression.Exploratory and learning promoted the expression of Ng in the peri-ischemic cortex.
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