The Effects Of Rehabilitation Training And Its Molecular Mechanism On Ability Of Learning And Memory In Vascular Dementia Rat Model

ObjectiveVascular dementia (VD) is one of main types of senile dementia. While the definite pathogenesis is still not clear. Rehabilitation plays an important role in the recovery of cerebral ischemia. In the experiment. We investigated the effect of rehabilitation training on the ability of spatial learning and memory, and study its molecular mechanism. Thid will provide theory foundation in clinic rehabilitation application and help to discover more effecteve therapy.MethodsTwo-vessel occlusion(2VO) was employed to make vascular dementia. Morris water-maze test was performed to study the ability of spatial learning and memory in each group of rats. Electrophysiological method was used to observe the effects on LTP of hippocampal CA1 region. The expressions of NMDAR1 in hippocampal region were determined by Western Blot.The expressions of Synaptophysin (SYN) protein was detected with immunohistochemitry. The ultrastucture changes of the synapses were observed with electron microscopy.1. Animals54 male Wistar rats weighting 280-350g were randomly divided into control group,vascular dementia group and vascular dementia with rehablitation training group. 2. Vascular dementia modelWe made animal model using developed two-vessel occlusion method.The rats were performed fasting while could drink 8-12h before operation. Apply abdominal anesthesia with 10% chloral hydrate (0.3ml/100g body weight). Fix the rats lying on the back, select median incision on abdomen, and perform blunt dissection to expose double-side common carotid. The artery was occlusion by 4 type line. In the control group, above steps were performed except for common carotid occlusion.3. Rehablitation trainingThe rehablitation training group was forced to balancing beam, rolling stick, tumbling barrel and screen training everyday for 4 weeks.4. Morris water maze training procedureBefore training, a free swim trial was run in which the platform was removed so that animals were adapted to temperature and environment of Morris water maze. During the training, a submerged platform was placed in the Morris water maze which make animal to learn the location of the platform that could be used to escape from swimming. The rats were placed in the maze in different starting positions that were equally distributed around the perimeter of the maze. The trial was lasted for 5 days. Record the escape latencies in each group.Probe trial: In the 6th day a probe trial was given which consisted of a 120s free swim period without the platform. Times of crossing the former site of the removed hidden platform were calculated.5. LTP examinationElectrode implantation sites were identified by using stereotaxic coordinates. Recordings of fiels excitatory postsynaptic potential (fEPSP) were made from the CA1. After 15 minutes stable baseline recording, high frequency stimulation(HFS) was given to induce LTP.6. immunohistochemitry and Western blotThe expression of NMDAR1 and SYN in rats were detected with Western blot and immunohistochemistry according to the prediction. Apply semi-quantu imaging analysis with Adobe Photoshop 6.0 and MetaMorph analysis system.7. Statistical analysisUse SPSS software for statistical disposition. All results were expressed by mean±standard variance. Statistical comparison was made by using one-way ANOVA.Results1. Morris water maze resultsThere was obvious difference in each group. The escape latencies in VD group were statistically longer than those in control group (p＜0.01), and the escape latencies in the rehabilitation training group were shorter than those in VD group(p＜0.01). The number of crossing the former site of the removed hidden platform in VD group were less than those in control group (p＜0.01), and the number in the rehabilitation training group were more than those in VD group(p＜0.01).2. LTP alteration in CA1 regionThere was no obvious difference between each group before HFS(P＞0.05). After HFS the fEPSP in control group were obviously elevatored and larger than those in VD group(p＜0.01). LTP couldn't be induced almost in VD group. Rehabilitation training improved the induction of LTP. The fEPSP in rehabilitation training group were obviously larger than those in VD group(p＜0.05).3. The expression of NMDAR1 in hippocampus regionThe average gray values of NMDAR1 positive product in VD group were lower compared with control group(p＜0.05). The average gray values in rehabilitation training group were higher compared with VD group(p＜0.05).4. SYN protein immunohistochemitryThe average optical density of SYN positive product in VD group were higher compared with control group(p＜0.05). The average optical density in rehabilitation training group were higher compared with VD group(p＜0.05).5. The ultrastucture changes of the synapsesThe number density of the synapses in the hippocampi decreased in the VD group comparaed with control group(p＜0.05). The number density of the synapses in the hippocampi in the rehabilitation training group were higher than those in the VD group(p＜0.05).ConclusionVascular dementia rats have deficiency in the ability of spatial learning and memory, and the induction of LTP was injuried in Vascular dementia rats. Rehabilitation training can improve the ability of spatial learning and memory in vascular dementia rats, and also can significantly elevate the induction of LTP. With the expression and changes of SYN,NMDAR1 protein,our research proved that rehabilitation changed some texture parameters of synapse for example the number density of the synapses and then influenced the plasticity of synapse, thus in the end it improve the function of behavior,learning and memory.