The Study Of The Protection Of Stilbene-glycoside On The Damage Of Synaptic Plasticity In Rats With Alzheimer Disease

Background and ObjectiveAlzheimer disease (AD) is a degenerate disease of centre nervesystem which character is progressive intelligence deterioration. Nowstudies have showed that the learning and memory have close relationshipwith the plasticity of synapse's structure and functions of centre nervesystem. Organism aging is often accompanied with decrease of synapse,abnormality of synapse's structure, calcium overload and the rapidattenuation of LTP. And in AD, studies have not only found the changesof the synapse's numbers and structure, but also the abnormal expressionof the calcium, the N- methyl- D- aspartate receptor subunit NR2B(NR2B), non-receptor protein-tyrosine kinase Src and the importantnuclear factor CREB which may play a key role in the information of LTP.Up to now, there are a little studies about the plasticity of synapse in ADin our country. Traditional Chinese medicine indicates that theFleeceflower Root may be help to the intelligence and longevity. Modernmedicine has studied the Fleeceflower and 2,3,5,4'-tetrahydroxystilbene-2-O-β-D-glucoside(TSG) which is the main component of theFleeceflower deeply and found it's multifold mechanisms ofimproving the AD rat's memory. But there are less studies about2,3,5,4'-tetrahydroxystibene-2-O-β-D-glucoside's contribution to theplasticity of synapse. This study discusses the relationship between AD and the plasticity of synapse and the molecular mechanisms about2,3,5,4'-tetrahydroxystilbene-2-O-β-D-glucoside's effect to thisplasticity through observing the ultramicrostructure of synapse, theconcentration of calcium ion in hippocampus, the changed expression ofNR2B, Src and CREB and the 2,3,5,4'-tetrahydroxystilbene-2-O-β-D-glucoside's effect to these factors. These provide theoretical foundationfor elucidating the pathogenesy of AD and finding effective medicine totreating AD.MethodSeventy- two rats sieved out through the Y-maze experiment weredivided randomly into control group, model group and TSG group.Alzheimer disease animal model was established by injected Aβ1-42 intothe rat's hippocampus. TSG group was intragastric administration by the2,3,5,4'-tetrahydroxystilbene-2-O-β-D-glucoside's (0.05g/kg.d),thecontrol group and model group were intragastric administration by partesaequales Sodium Chloride. Y- maze experiment was used to detect thefrequencies what the rats needed to handle the methods of dodgingelectric stimulation on the 7th, 14th,21th and 28th day; HE stain was usedto observe the neuronal morphous in CA1 of the hippocampus after 28days; Congo red stain was used to view the deposition ofβ-amyloid;Electron microscope was used to view the structure of synapse in CA1of the hippocampus; and transmission electron microscope and image analyzer were utilized to survey and quantitative analysis textureparameters of the type Grayâ… synaptic interface in area CA1 of thehippocampus, intracellular Ca2+ in the cells of the hippocampus wasloading measured by LASER Copolymerization Focus Fluo-3/AM; Theexpression of NR2B,p-Src,p-CREB in area CA1 of the hippocampuswas determined by immunity tissue method; RT-PCR was used tomeasured the expression of NR2BmRNA,SrcmRNA,CREBmRNA inthe hippocampus, and Western blotting to detect the expression ofNR2B,p-Src,p-CREB in the hippocampus.Result1 The rats in AD model need more electrical stimulus for learning toescape than the rat in control group and TSG group (P＜0.05). Thisdifference has statistical significance.2 The neurons in the hippocampal CA1 areas of the rats in ADmodel group decrease and distribute irregularly. The damages of thestructure of synapse in CA1 area are more prominent. The neuron in thehippocampal CA1 areas of the rats of the rats in TSG group increase anddistribute more regularly and the damages of the structure of synapse inCA1 area are alleviative.3 The width of synaptic cleft in the hippocampal CA1 areas of therats in AD group is remarkably increased, the thickness of PSD reducesapparently, flat synapses increase significantly, negative curve synapses and perforated synapses reduce apparently. But TSG can reverse thesepathological change of the synaptic interface (P＜0.05). Theseabove-mentioned datas are differential between the AD model group andthe TSG group and the difference has statistical significance (P＜0.05).4 The calcium ion concentration in the hippocampal neuron of therats in AD model group is prominently higher than it in control group(P＜0.05).5 The expression ofNR2B,p-Src,p-CREB in the hippocampal CA1area of the rats in AD group is prominently less than it in controlgroup(P＜0.05) and TSG group(P＜0.05). It has statistical significant.6 The expression of the mRNA of NR2B,p-Src,p-CREB in thehippocampal CA1 area of the rats in AD group is prominently less than itin control group(P＜0.05) and TSG group(P＜0.05). It has statisticalsignificant.7 The expression ofNR2B,p-Src,p-CREB in the hippocampus ofthe rats in AD group is significantly less than it in the control group(P＜0.05) and TSG group(P＜0.05).Conclusion1. We injected Aβ1-42 into the rat's hippocampus in order to foundthe model of AD. This model had a good reproducibility and stabilization.This model was an ideal model of groundwork study in AD.2. AD models induced by Aβ1-42 existed the damage of synaptic plasticity may be because it could induce the structural impairment ofsynapse and overloading of intra-ceUular Ca²⁺ in the hippocampus,reduced the expression of NMDA receptor subunit NR2B,non-receptortyrosine protein kinase Src phosphorylation and intranuclear transcriptionfactor CREB phosphorylation in the hippocampus differently.3. improvement of the state of intra-cellular Ca²⁺ overloading inneurons of the hippocampus and texture parameters' retroconversion ofthe type Grayâ… synaptic interface in area CA1 of the hippocampus mightbe the morphologic foundation that TSG could relieve the damage of thesynaptic plasticity of strucyure of the AD rats.4. TSG could protect the synaptic plasticity of function in thehippocampus impaired by Aβ1-42 and enhanced AD rats' capabilities oflearning and memory, which might be through increasing the expressionNMDA receptor subunit NR2B, Src phosphorylation, nuclear proteinCREB phosphorylation in the hippocampus.