The Study On Protective Effect Of Ginsenoside Rg2 On Brain Of Rats With Alzheimer's Disease

Alzheimer's Disease (AD) is the disease with clinical charactors of progressive memory loss and disorder of recognition and language .The rate of suffering AD is rising lasting owning to the increasing of the number of old men, so studing the reasons and mechanisms of AD, finding a effective method to therapy AD become the studing focus of medical science. Basic studies show that, Ginsenoside Rg1 is a kind of effective medicine to therapy AD, Ginsenoside Rg2 is in the same group with ginsenoside Rg1. There is consistence between their molecular structures, but the effect of ginsenoside Rg2 on AD hasn't been studied so far. This experiment used rats for AD models by injecting Aβ25～35 to the hippocampus of rats, examined the results by praxiology, morphological and immunohistochemical methods. The objective is to study whether ginsenoside Rg2 has preventing and therapeutic effect on AD.84 cleaning group rats, one half is male and another half is female, are divided randomly into model group, normal group, control group(model+ xing ding), dissolve medium group(1,2-bingerchun), ginsenoside Rg2Ⅰgroup (model +ginsenoside Rg2 with low dose) , ginsenoside Rg2Ⅱgroup (model+ ginsenoside Rg2 with middle dose) and ginsenoside Rg2Ⅲgroup (model+ ginsenoside Rg2 with high dose) and . NS was given to model group and normal group with dose of 2ml.kg-1.d-1;Xingding was given with dose of 3.6mg/kg·d to rats of control group; Dissolve medium was given with dose of 2ml/kg·d to rats of dissolve medium group. Ginsenoside Rg2 was given with dose of 3mg/kg·d to rats of ginsenoside Rg2Ⅰgroup, with dose of 6mg/kg·d to rats of ginsenoside Rg2Ⅱgroup and with dose of 12mg/kg·d to rats of ginsenoside Rg2Ⅲgroup.The rats of groups above were injected abdomen for 14 days. On the fifteenth day, NS was injected into hippocampus of rats of normal group(4ul), Aβ25～35 was injected into hippocampus of every rats with the same doseexcepted that of normal group. Praxiology examination including Morris water maze and step-down test was carried out after 2 weeks.Then, the rats'brain of every group was got to observe the general changes of neuron in cerebral cortex and hippocampus; SP by staining of Bielschowsky silver; the expression of synaptophysin (SY )by staining of anti-SY using immunohistochemical methods by light mroscope(LM) and observe super microstructure of neurons in hippocampus by transmission electron microscope(TEM).The results of praxiology test showed that , compared with model group, the studying and memory abilities of ginsenoside Rg2Ⅱ,Ⅲgroup had improved evidently; the studying ability of ginsenoside Rg2Ⅰgroup had improved obviously, however, the memory ability of that hadn't improved obviously. The results of staining with HE showed that , compared with normal group, the number of neurons of model group and dissolve medium group decreased seriously, and lots of necrosis neurons were observed; the number and morphology of neurons in cerebral cortex and hippocampus of control group and ginsenoside Rg2Ⅰ,Ⅱ,Ⅲgroups had improved ,especially, the morphology and structure of neurons in hippocampus of control group and ginsenoside Rg2Ⅲgroup were close to that of normal group. The results of staining with bielschowsky silver showed that, SP were observed only in cerebral cortex of model group, dissolve medium group and ginsenoside Rg2Ⅰgroup,not in other groups. The results of staining SY showed that , compared with normal group, the expression of SY of model group and dissolve medium group;in contrast to model group, the expression of SY of ginsenoside Rg2Ⅰ,Ⅱ,Ⅲgroup was improved obviously. The results observed by TEM showed that, in model group and dissolve medium group, the numbers of dark nerons in hippocampus increased evidently and pyknosis in different steps were observed;mitochondria swelling and lipofuscin were observed in cytoplasm;there was neuropil cavitation, and the neurofilament and mitochondria decreased obviously.In thehippocampus of control group and ginsenoside Rg2Ⅲgroup ,most neurons were normal, mitochondria and rough endoplasmic reticulum(RER) were abundant. In hippocampus of ginsenoside Rg2ⅡandⅢgroups,some dark neurons were observed.The result of the experiment showed that ,AD model could be set up successfully by injecting Aβ25～35 into hippocampus.Ginsenoside Rg2 groups of different doses could improve the abilities of studing and memory of AD rats, and the effect depended on the dose; improve the morphology of neurons in cerebral cortex and hippocampus of AD rats.The effect of ginsenoside Rg2Ⅲgroup was similar with that of control group. The results of this experiment would supply the theory foundation for studing the mechanisms of AD and medicine for AD.