Plasticity Of Hippocampal Structure And Expression Of Microtube Associated Protein Tau In The Spatial Learning And Memory Of Rats

ObjectiveTo explore the mechanisms of hippocampal morphological changes resulted from the information storage,we investigated plasticity of hippocampal structure and expression of microtube-associated protein tau in the spatial learning and memory of rats.MethodsMale SpragueDawley rats,2 months,were randomly divided into the model group (n=20),the swimming group(n=20) and the normal group(n=20).The model of spatial learning and memory was established by the Morris water maze training for 7 days in rats.The distribution change of mossy fiber was studied by Neo-Timm staining.The distribution change of microtube-associated protein tau-1 in the hippocampus CA3 region was observed by immunofluorescence staining.Expression change of tau was detected by Western blotting.Results1.Latency of platform in the model group decreased from 35.18±10.24 s to 6.54±2.86 s and the path to reach the platform became the linear from the tendency after Morris water maze training for 7 days.2.In the swimming group or normal group,mossy fiber terminals were only distributed in the stratum lucidum.In the model group,mossy fiber terminals were also found in the CA3 stratum oriens region by Neo-Timm staining.Mossy fiber spouting scale:the model group was 3.30±0.49;the swimming group was 0.88±0.47 and the normal group was 0.39±0.11((?)±s,n=20,P＜0.01).Distribution of tau-1 was obviously observed in stratum pyramidale and stratum oriens region of CA3 region by immunofluorescence staining in the model group.3.The expression of non-phosphorylated tau-1(Ser198/199/202) in the model group was highly up-regulated compared with the other groups(P＜0.05).No significant changes of phosphorylated tau at Ser396 and Ser404 were found in the model group compared with the swimming group or the normal group(P＞0.05). Conclusion1.Spatial learning and memory induced the remodeling of the hippocampal mossy fibers of CA3 region in rats.Mossy fibers could be a ideal structure for studying the relationship between axonal remodeling and learning.2.Non-phosphorylated tau-1(Ser198/199/202) might be involved in the hippocampal spatial learning and memory,and phosphorylated tau at Ser396 and Ser404 were not the key point of the learning and memory.