| Objective: In China, Stroke is a common disease with a high rate of morbility and disability. Sequla occurred in 70-80% of the patients ,such as cognitive impairment, difficulty in walking. Stroke is a risk factor for VD, 40% of the VD patients lose self-care ability. It not only bring great pain to the sufferers, but also take burden to their families and society. Nowadays, stroke rehabilitaion developes rapidly, but curative effects are influenced by many aspects such as learning memory ability.So how to improve the ability of learning and memory becomes the focus of attention.Neurogenesis, the production of neurons, continues in two regions of the adult mammalian brain: the subgranular zone (SGZ) of the hippocampal dentate gyrus (DG) and the subventricular zone (SVZ) of the lateral ventricle In the DG, newborn neurons are generated in the SGZ, then migrate and differentiate into mature neurons in the granule cell layer (GCL), where they are functionally integrated into the neural circuit in the DG.PSA on NCAM is developmentally regulated thus playing a prominent role in different forms of neural plasticity spanning from embryonic to adult nervous system, including axonal growth, outgrowth and fasciculation, cell migration, synaptic plasticity, activity-induced plasticity, neuronal-glial plasticity, embryonic and adult neurogenesis. It has a great role on memory and learning ability.Lots of studies have reported that Acetylcholine (ACh) is one of the most important neurotransmitters in learning and memory, chronic cholinergic stimulation with ChEI-treatment promotes the survival of newborn neurons in the DG. The neurogenic regions DG is extensively innervated with basal forebrain cholinergic (BFC)neurons.Neurons in the DG abundantly express nicotinic acetylcholine receptors (nAChRs). The extracellular ACh level in the brain varies depending on various changes which occur under physiological conditions. Learning, motor activity and estrogen treatment increase ACh release in the cortex and hippocampus.Our study was to indicate that the exploring learning has great influence on the memory learning ability and the express of PSA-NCAM and nACHR in rats after MCAO. Futhermore, elucidate the mechanism of restoring the damage nervous system.Methods: The study was made up of two setions. One section was to establish the MCAO model:120 male Sprague-Dawley rats were adopted, 5rats per standard cage ,then 80 rats were randomly chosen for making the model of MCAO by electric coagulation successfully after 7days.After 24 hours of MCAO, there were no significant difference among them by Bederson method (P>0.05),after that they were randomly divided into social communication group(n=40, 5 rats per standard cage), exploring learning group(n=40, 10 rats per exploring learning cage) and sham operated group(n=40, 5 rats per standard cage);10 rats in each group were randomly chosen and the spatial learning and memory were tested by Morris water maze for 5 days after 23 days of MCAO. In section two,the rat's cerebral tissue fixed up via perfusion of 4% paraformaldehyde solution, then we respectively observed the pathological change of hippocampus in each group at 1th and 28th day after the operation, all rats were also randomly assigned to be killed after MCAO: at the 1th,3nd,7th, 14th,28th day,5 rats were randomly killed separately in each group. The expression of PSA-NCAM,nACHR in dentate gyrus were examined by 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-operated group. 2. Morris water maze:The first day of Morris water maze, there were no significant difference among the groups(P>0.05); From 2nd to 5th days the escape latency of exploring group was shorter than the social communication group (P<0.05);From 2nd to 3nd days the escape latency of the sham-operated group was shorter than the exploring learning group (P<0.05). From 4th to 5th days there were no significant difference of the escape latency between the sham-operated group and the exploring learning group (P>0.05).From 2nd to 5th, the escape latency of the sham-operated group was shorter than that of the social communication group (P<0.05).3. The expression of PSA-NCAM in dentate gyrus: The 1th day the PSA-NCAM positive cells in the exploring learning group compared with those in social communication group had no significant difference (P>0.05), there were little expression in the sham-operated group and less than the operated group (P<0.05); the 3nd and 7th day,the PSA-NCAM positive cells in exploring learning group were more than the cells in social communication group but there were no significant difference between them(P>0.05),the positive cells in the operated group were more than those in the sham-operated group(P<0.05);the 14th and 28th days the PSA-NCAM labled cells in the exploring learning group were more compared with the cells in social communication group (P<0.05),the cells in social communication group were more than those in the sham-operated group (P<0.05). 4. The expression of nACHR in dentate gyrus:The 1th,3th,7th and 14th day the nACHR labeled cells in the sham-operated group were more than the cells in the operated groups(P<0.05) , the 28th day compared with the exploring learning group their had no stastical difference(P>0.05);the 1th, 3nd and 7th day the positive cells in the social communication group and the exploring learning group had no significant statistical difference (P>0.05);the 14th and 28th day the nACHR labeled cells in exploring learning group were more than those in the social communication group(P<0.05).Conclusion: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 Exploring learning could enhance the memory and learning ability of local infarcted rats.3 Exploring learning can enhance the expression of PSA-NCAM and n ACHR in dentate gyrus of adult Rats after Unilateral Local Cerebral Infarction.4 The more express of PSA-NCAM, nACHR maybe enhance the ability of learning and memory of rats in the exploring group. |
PDF Full Text Request