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Antagonistic effects of extract from leaves of Ginkgo biloba on glutamate neurotoxicity

摘要撰写人 : TsingHua
浏览次数 : 17  词语: 300   出版日期: 八月 30, 1997
AntagonisticefectsofextractfromleavesofGinkg obilobaonglutamateneurotoxicityZHULi,WUJuan ,LIAOHong,GAOJing,ZHAOXiaoNing,ZHANGZuXua n(SchoolofMedicine,NanjingUniversity,Nanjin g210093,China)1ProjectsupportedbytheNatural ScienceFoundationofJiangsuProvince,№BK93030 311.Received19960715Accepted19970227KEY WORDSculturedcels;neurons;calcium;cerebralc ortex;arcuatenucleus;glutamates;Ginkgobilob a;ginkgolideB;quercetinAIM:Todeterminewheth ertheextractofleavesofGinkgobilobaL(EGb)and severalactiveconstituentsofEGbhaveprotectiv eefectsagainstglutamate(Glu)inducedneurona ldamage.METHODS:Microscopyandimageanalysiso fnucleusareasinthearcuatenuclei(AN)ofmicewe remade.Theneuronalviabilityinprimaryculture sfrommousecerebralcortexwasasesedusingMTT[3 (4,5dimethylthiazol2yl)2,5diphenyltet razoliumbromide]stainingandtheintracelularf reecalciumconcentration([Ca2+]i)ofsingleneu ronwasmeasuredusingFura2.RESULTS:EGb(25mg ·L-1)anditsconstituentginkgolideB(GinB,2mg· L-1)protectedtheneuronalviabilityagainstGlu inducedinjury,andpreventedtheGluinducedel evationin[Ca2+]i.EGb(3-10mg·kg-1)atenuatedt hedecreaseofnucleusareasinarcuatenucleiindu cedbyGlu(1g·kg-1,sc).CONCLUSION:EGbandGinBp reventneuronsfromGluneurotoxicitythroughred uctionoftherisein[Ca2+]i.Glutamateneurotoxi city(GNT)participatedintheneuronlossassocia tedwithanumberofneurodegenerativediseases,e g,AlzheimersdiseaseandHuntingtonsdisease〔 1,2〕.ToinvestigatetheGNTandantiGNTdrugs,ap rimarycelculturesystemderivedfromfetalmouse neocortexwasused.Invivostudiesweretodetectt heefectsinarcuatenucleusinhypothalamus,whic hwerenotfulyprotectedbythebloodbrainbarier (BBB)inimmatureanimals〔3〕.OveractivationofG lureceptorscausedanexcesiveinfluxofCa2+into theneuron,whichresultedinactivationoflipase ,protease,andproteinkinaseC,subsequentlyled tothegenerationoffatyacids,freeradicals,and ultimatelyneuronaldeath.Ca2+overloadingandl osofCa2+homeostasismightplayanimportantrole inGNT〔4,5〕.TheextractofleavesofGinkgobiloba L(EGb)contained24%offlavonoidglycosides,the aglyconofwhichwasaflavonol(includingquercet in,kaempferol,andisorhamnetin),6%ofterpenel actones(includingginkgolidesA,B,C,J,andbilo balide),and70%ofothersubstances(proanthocya nidins,organicacids,sugars,etc)〔6〕.EGbhadpr otectiveefectsonGNTinadosedependentmanneri nbothculturedmousecorticalneuronsandculture dhumanhippocampalneurons〔7〕.Thisstudywastoi nvestigatewhetherEGborsomeofitsconstituents protectedneuronsagainstGNTinvitroandinvivo. GinkgolideBMATERIALSANDMETHODSReagentsEGbwa stheproductofJarowFormulas,Inc(LosAngelesCA ,USA),whichwasanalyticalycontroledtoensurec onsistencyofitscomposition,andstandardizedt ocontain24%flavonoidglycosidesand6%terpenel actones.GinkgolideB(GinB,BN52021,lyophilisa t)wastheproductofIpsen(30rueCambronne,Paris ,France).Quercetin(Que),Fura2,HEPES,andLg lutamicacid(LGlu)werepurchasedfromSigma.L Gluweredisolvedindeionizeddistiledwateranda djustedtopH70withNaOH1mol·L-1.Dulbeccosmo difiedEaglemedium(DMEM)andtetrazoliumsalt(M TT)werepurchasedfromGibcoandFluka,respectiv ely.OtherreagentswereofARgrade.Alsolutionsw erepreparedwithdeionizeddistiledwater.Prima rycorticalcelcultureMousecorticalneuronswer epreparedfrom14-17doldembryosusingtechniq uewithminormodification〔8〕.Thecerebralcorte xwasminced,incubatedin0125%trypsinat37℃for 10minandstoppedwithHanksbalancedsaltsoluti on.ThecelpeletwasresuspendedinDMEMsupplemen tedwith20%heatedinactivatedfetalbovineseru m,LGlu20,NaHCO324,HEPES10,andglucose25mmo l·L-1.Celswereseededon96welplates(3×105cel sperwel)coatedwithLpolylysingandincubated at37℃in5%CO2atmosphere.After5-7dinculture,n onneuronalcelsdivisionwashaltedby1-3dofexp osuretocytosinearabinoside(10μmol·L-1).Thec ulturemediumwasrenewedevery3-4d.Treatmentwi thGluandEGbExperimentswerecariedoutafter7di nculture.FolowingtheincubationwithEGb(25mg ·L-1),Que(20mg·L-1),andGinB(2mg·L-1)orbothQ ueandGinB(20mg·L-1+2mg·L-1),respectivelyfor 24h,celculturewasexposedtoGlu(05mmol·L-1)at25℃for30min,andthenthesolutionwasthoroughlywashedandtransferedtoCO2incubatoruntilthenextdayforMTTasayormicroscopy.MTTstainsMTTin

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