| Objective: To study effect of Kangnaoling@ on learning and memory impairment induced by amyloid # -peptide in elder rats,as well as the changes of expression of NMDA receptor NR2B subtype, synaptophysin and SI00# ,apoptosis and configuration in hippocampus.Methods: KangnaolingHIwas made of seven kinds of Chinese drugs. Sixty Wistar rats, aged 10-12 months and weighed 350-400g at the beginning of the experiment, were divided by random number table into the five groups: NS control, model group, low dose of Kangnaoling@ group, high dose of Kangnaoling@group, estradiol benzoate group. The elder rats were injected bilaterally Ap25~35 10ug into the hippocampus to induce learning and memory dysfunction. Kangnaolinglll was administered with two different doses(2g?4g.d-1 ) and the rats of estradiol benzoate infection group were injected with estradiol benzoate Img.kg-1 once for every three days 24h after the injection of Ap25~35for 18d. The rats of NS group and model group were administered with distilled water.The Morris water maze were used together to determine effects of A@25-35 and Kangnaoling III on learning and memory. The rats were trained in the Morris water maze for 5 days. The latency of escaping was recorded in the place navigation test. The percentage of the time in each quadrant was recorded in the spatial probe test in the fifth day afternoon. Eighteen days after injection ,brain tissues were fixed with 10 % neutral formalin solution.The section were stained with haematoxylin-eosin (HE).The amyloid deposits were detected using Congo red. The pathomorphological changes of the neurons were observed by Nissl staining.The expression of synaptophysin ,S100@ ,NMDAR2B and caspase-3 were analyzed by immunohistochemical method.Results: The latency of escaping in the five groups decreased as time passed by. In the model group, the latency of escaping significantly increased (P<0.05), while thepercentage of time in the platform quadrant obviously decreased (P0.05) compared with the NS group. NS group had only slight glial cells hyperplasia and CA1 pyramidal cells disorder and loss where NS injection crossed. Also in model group, a decrease in the number of neurons in cortex and hippocampus, a massive glial reaction, were detected by HE staining. By electron microscope, A25-35 induced hippocampal neurons to undergo apoptosis was observed in model group, including morphological changes of chromatin condensation, chromatin agglomerated formation, nucleus shrinkage. In high dose of Kangnaoling group the apoptosis of neuron reduced. The laminar distribution patterns of immunoreactive products of anti-synaptophysin were found in the hippocampal formation. The corrected optical densities (COD)of immunoreactive products in the two brain regions were significantly decreased in model group in comparison with NS group(P0.0l). Kangnaolinglll, giving for 18d, increased the expression of synaptophysin. the expression of S-100 of model group increased in comparison withNS group (P<0.05). Compared with model group, the expression of S-100 of high dose of Kangnaolinglll group significantly decreased (PO.05). Compared with model group, the immunoreactivity density of NR2B receptor in hippocampus of low dose of Kangnaoling group?high dose of Kangnaolinglll group?estradiol group increased(P<0.05). Low dose of KangnaolingIIIgroup?high dose of Kangnaoling group,estradiol group and control group , compared with each other , P>0.05. Compared with model group, the positive rate of caspase-3 protein of high dose of KangnaolingIIIgroup,low dose of Kangnaolinglll group and estradiol group significantly decreased(P<0.01).Conclusion: Kangnaoling III could enhance the impaired learning and memory induced by A25~35 in elder rats in Morris water maze test, inhibit apoptosis of hippocampal neurons,increas expression of hippocampal NR2B receptor and Synaptophtsin, adjust expression of S-100 . The AP25~35 injected into hippocampus could induce neurotoxicity. Positive correlation was showed between neurotoxicity and glial cells hyperplasia. Kan...
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