神經元之間的信息傳遞突觸傳遞（Synaptictransmission)突觸（Synapse)

電突觸(electricsynapse)(少見）

化學突觸

(chemicalsynapse)（主要形式）

--through神經遞質（neurotransmitter)（囊泡運輸）2013諾貝爾生理學與醫學獎

授予3名美德科學家

2013年10月07日

2013諾貝爾生理學或醫學獎授予JamesE.Rothman,RandyW.Schekman（美國）&ThomasC.Südhof（德國），以表彰他們在細胞的囊泡運輸機制研究中的杰出貢獻。AcetylcholineGlutamateGABAAdrenalineDopamineNoradrenalineSerotoninHistamine…神經遞質

特定的化學物質負責突觸處信號的化學傳遞Monoamines(單胺類遞質)兒茶酚胺(catecholamine,CA)多巴胺（Dopamine,DA)去甲腎上腺素（Noradrenaline,norepinephrine,NA或NE)腎上腺素（adrenaline,epinephrine,A或E)吲哚胺(indolamine)5-羥色胺（Serotonine,5-HT)兒茶酚SerotoninMilestonesintheresearchhistoryofDACarlson(1958):highlevelinstriatum,70%ofthetotalcontentinbrainHornykiewicz(1960):criticallossofDAneuronsin

PDpatients

Dahlstrom(1964):prescribeDApathwaysinCNSbyfluorescent-histochemisty1971:6-OHDAistoxicforDAfunction1976:antipsychoticactivitycorrelatedwithDAreceptorbindingactivity1978:detectDAconcentrationwithvoltammetry1979:classificationofDAreceptors1982:detectDAreleasebymicrodialysis1983:MPTPneurotoxicity1988:D2receptorcloned1991:DAtransportercloned1996:knockoutDAtransportermice……1,

anindependentneurotransmitterinCNS2,aprecursortonoradreanline(NA)inNAneuronsDAis…NobelPrize2000inPhysiologyorMedicine“Theawardhasbeengivenforstudiesonsignaltransductioninthenervoussystems.”ArvidCarlsonPaulGreengardEricKandel1.1PATHWAYSinCNScellbodylocationprojectionpathway1962年，Falk-Hillarptechnique(甲醛誘發熒光法)Formaldehydevapourmonoaminebright-greenflurorescence(DA,NE)yellowflurorescence(5-HT)1972年瑞典學者Bjorklund和Lindvail創立了乙醛酸誘發熒光法單胺類神經遞質腦內分布的觀察手段2.Useofimmunofluorescencetechnique

Enzymes，transporters，……1.Useoffluorescencehistochemistry(Falck&Hillarp)單胺類神經遞質腦內分布的觀察手段

MajorNoradrenergic(blue)去甲腎上腺素,Dopaminergic(red)多巴胺

andSerotonergic(green)

5-羥色胺PathwaysintheCNS

A8(lateral,caudal,dorsaltoA9)

A9(substantianigra,SN黑質）

A10

(ventraltoA9,ventraltegmentum,腹側被蓋區)

A12(arcuatenucleus，弓狀核)A8-A10contains70%oftheDAneuronsinthebrain

LocationofDAcellbodies（多巴胺胞體分布）A8–A10:midbrain中腦A11–A17:diencephalon間腦A9A10nigrostriatalpathway:黑質-紋狀體通路

（運動控制）A8,A9----striatum（紋狀體)caudatenucleus（尾核）,putamen（殼核）,amygdala（杏仁核）mesolimbocorticalsystem:中腦-邊緣皮質投射

（情感和認知）A10----nucleusaccumbent（伏隔核）,olfactorytubercle（嗅結節）,

prefrontal（前額葉皮層）andperirhinalcortex（嗅皮層）A9,A10---anteriorcingulatecortex(前扣帶皮層）tuberoinfundibularsystem:結節漏斗系統（DA能短投射）

A12---pituitarygland（垂體）（抑制垂體分泌激素）下行束－脊髓(Spinalcord)（調節軀體和內臟感覺運動）

projectionpathwaysofDAneurons（神經投射通路）nigrostriatalpathway:黑質-紋狀體通路

（運動控制）A8,A9----striatum（紋狀體)caudatenucleus（尾核）,putamen（殼核）,amygdala（杏仁核）mesolimbocortical

system:中腦-邊緣皮質投射

（情感和認知）A10----nucleusaccumbent（伏隔核）,olfactorytubercle（嗅結節）,

prefrontal（前額葉皮層）andperirhinalcortex（嗅皮層）A9,A10---anteriorcingulatecortex(前扣帶皮層）tuberoinfundibularsystem:結節漏斗系統（DA能短投射）

A12---pituitarygland（垂體）（抑制垂體分泌激素）下行束－脊髓(Spinalcord)（調節軀體和內臟感覺運動）

projectionpathwaysofDAneurons（神經投射通路）nigrostriatalpathway:黑質-紋狀體通路

（運動控制）A8,A9----striatum（紋狀體)caudatenucleus（尾核）,putamen（殼核）,amygdala（杏仁核）mesolimbocortical

system:中腦-邊緣皮質投射

（情感和認知）A10----nucleusaccumbent（伏隔核）,olfactorytubercle（嗅結節）,

prefrontal（前額葉皮層）andperirhinalcortex（嗅皮層）A9,A10---anteriorcingulatecortex(前扣帶皮層）tuberoinfundibularsystem:結節漏斗系統（DA能短投射）

A12---pituitarygland（垂體）（抑制垂體分泌激素）下行束－脊髓(Spinalcord)（調節軀體和內臟感覺運動）

projectionpathwaysofDAneurons（神經投射通路）nigrostriatalpathway:黑質-紋狀體通路

（運動控制）A8,A9----striatum（紋狀體)caudatenucleus（尾核）,putamen（殼核）,amygdala（杏仁核）mesolimbocortical

system:中腦-邊緣皮質投射

（情感和認知）A10----nucleusaccumbent（伏隔核）,olfactorytubercle（嗅結節）,

prefrontal（前額葉皮層）andperirhinalcortex（嗅皮層）A9,A10---anteriorcingulatecortex(前扣帶皮層）tuberoinfundibularsystem:結節漏斗系統（DA能短投射）

A12---pituitarygland（垂體）（抑制垂體分泌激素）下行束－脊髓(Spinalcord)（調節軀體和內臟感覺運動）

projectionpathwaysofDAneurons（神經投射通路）SynthesisStorageReleaseEliminateReuptakeMetabolism1.2NEUROCHEMISTRYDopamineVesiclesynthesisstoragereleasereceptoreliminationreuptakemetabolism神經遞質的Neurochemistry示意圖Enzymes:

tyrosinehydroxylase(TH,酪氨酸羥化酶）Dopadecarboxylase(DDC,多巴脫羧酶）SYNTHESIS(合成）DAandNAsynthesisareSimilarPrecursor:

tyrosine(酪氨酸）

SYNTHESISTyrosinehydroxylase(TH,酪氨酸羥化酶）Cytoplasmicenzyme：tyr

L-dopa

Km=5

10-6M

<<腦內[Tyrosine]Fe2+,O2,andtetrahydropterine(BH4)Substrate-specificLowactivity,lowconcentrationInhibitedby

-methyl-p-tyrosineRate-limitingstepDA、NA能神經元的標志酶

SYNTHESISDopadecarboxylase(DDC,多巴脫羧酶）

cytoplasmicenzyme：L-dopaDArequirespyridoxalphosphate(vB6)lowsubstratespecificageneralL-aromataicamino-acid

（組氨酸，酪氨酸，色氨酸，苯丙氨酸）decarboxylase

芳香族左旋氨基酸脫羧酶

Highconcentration,highactivity

---lowconcentrationofL-dopainbraininhibitedby

-methyldopa

(Carbidopa+L-DOPAforPDtreatment)

（L-DOPA能通過BBB,DA不能；Carbidopa抑制外周DDC活性）Tyr

DopaDATHDDCControlsofsynthesis

SYNTHESISRate-limitingControlsofsynthesisInhibitTHactivity

enzymeinhibitorsend-productinhibitionDAautoreceptorsinpresynapticmembraneIncreaseTHaffinity

impulseflow(BH4increased)

Givetheprecursordopa(augmentDA)

SYNTHESISRegulationofTH1,Enzymeactivity

---Short-term,rapidchanges

（突觸水平，短而快速）

SYNTHESISByPhosphorylationatserine(Ser)residue

（絲氨酸磷酸化）

Post-transcriptionalregulationN

酪氨酸羥化酶（TH）上的磷酸化調控的位點atleastfourdistinctserineresiduescouldbephosphorylatedbyatleastninedistinctproteinkinasesSer40seemstobeacommontargetforallthekinases.Itisthoughtthatthissiteproducesaconformationalchangeintheenzymethatreducesitsaffinityforcathecholamines.RegulationofTH2,Enzymesynthesis

---Long-lastingchanges

（胞體水平，慢而持久）

SYNTHESISByregulatinggenetranscriptionTranscriptionalregulationCaffeine,nicotine,morphine：up-regulateAntidepressants:down-regulateStorageSTORAGE（儲存）StoredinvesiclesTransporterinthevesiclemembrane

vesicularmonoaminetransporter,VMAT

（囊泡單胺轉運體）12transmembranedomain

N-terminal,C-terminal----inplasma

H+dependent2H+/1DA(orNA)Inhibitedby:reserpine

利血平

（降壓藥；抗精神病藥.副作用：抑郁癥）

tetrabenazine丁苯喹嗪丁苯那嗪所有單胺類神經遞質共同的轉運體StructureoftheVesicularMonoamineTransporter(VMAT2)TheH+-dependentVMAT-2:Putativelycontains12hydrophobictransmembranespanningregionsHasintracellularN-andC-terminaldomainsHavealargeluminalloopbetweenTM1and2with3-5N-linkedglycosylationsitesHavePKAandPKCphosphorylationsitesinintracytoplasmicportionsVMAT２主要分布在神經元，VMAT１在非神經組織

STORAGERES(reserpine)利血平與單胺類遞質結合TBZ(tetrabenazine)丁苯喹嗪VMAT

existsintwodifferentconformationsGranulematrix抑制遞質從囊泡泄漏1NE(or1DA):2H+TheRESbindingsitehasahighaffinityforthesubstratesTheTBZbindingsitehasalowaffinityforthesubstratesRELEASE（釋放）Dopaminergicneuronsstimulation

dopaminereleasefromtheterminusA9A10SNstimulationDArelease

Vesicularexocytosis（胞裂外排）

RELEASE--autoreceptorsatpresynapticmembrane(activation/attenuaterelease)shortbutrapideffect

--nervestimulationincreasesTHactivity(highaffinityfractionofTHincreased)Otherfactors:--GABAinhibitDArelease--highK+,lowNa+enhanceDAreleaseControlsofDAreleaseEliminate

（消除）Reuptake（重攝取）Metabolism（代謝）REUPTAKE(重攝取）DopamineTransporter（DAT）DAreuptake12transmembranedomainsN-terminal,C-terminal----inplasmaDAspecification

Na+/Cl-dependent2Na+,1Cl-/1DAMembranepotentiationdependentBlockedbynomifensine

諾米芬新（forDAT）Transporterinthemembraneofneuralcellsdopaminetransporter(DAT)(cocaine,amphetaminecanalsobetakenup)StructureoftheDopamineTransporter(DAT)Havealargeextracellularloop2betweenTM3and4with2-4N-linkedglycosylationsites.（糖基化位點與轉運體在膜上的定位有關）Havemultiplephosphorylationsitesonthecytoplasmicdomains（胞質側各位點的磷酸化對轉運功能具有調控作用）DATandNETTheprimetargetsforPychostimulantdrugs（精神興奮性藥物的主要靶點）

cocaine,amphetamine,antidepressant……6-OHDA:6-羥基多巴胺

ToxinsforbothDAandNAneuronsBetakenupintonerveterminalsbyDAT/NETOxidisedanddegeneratetheterminals

------chemicalsympathectomy(化學性交感神經切斷術)MPTP:(1-甲基-4-苯基-1,2,3,6四氫吡啶,

1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine)

ToxinsspecificforDA

neuronsDependsonDATinneuronsDeaminatedtoMPP+whichisthentakenupbyDAnerveterminals

AnusefulmedicineinPDanimalmodelNEUROTOXINS（神經毒素）黑質部位DA神經元和樹突有高表達的DAT，易受MPTP高度選擇性損害黑質的DA神經元內含有Fe2+/Fe3+，是氧化應激的內在催化條件MPTPdeliveryinducedasignificantlossofTH-immunoreactiveneuronsinSNpc,andanotablyreduceofTH-immunoreactivestriatalfibersat4dfollowinglastMPTPinjection.Metabolism（代謝）Deamination(去氨基化）O-methylation（氧位甲基化）Twoimportantenzymesinvolved:monoamineoxidase(MAO，單胺氧化酶）catechol-O-methyltransferase(COMT，兒茶酚胺氧位甲基移位酶）MAO:deaminationenzymeinthemembraneofmitochondria

（線粒體膜上）

reactioninthecytosolplasma（胞漿內）

Subtypes:

MAOA–moreactiveinNAand5-HTneurons

MAOB–dominantenzymeforDAneuronsInhibitors:

selegiline(forMAOB)

METABOLISMCOMT:

O-methylation

extracellularenzyme（細胞外）

reactionoutsidecellsinhibitors:pyragallol,catechol(tootoxicforclinicaluse)entacapone,tolcapone(mainly

inPDtreatment)MAOHVA高香草酸MAOCOMTMHPEA

3-甲氧-4羥基－苯乙胺COMT外周終主要產物DOPAC3,4-雙羥苯乙酸中樞主要終產物中樞主要途徑DA的降解代謝突觸前重攝取（reuptake）突觸后攝取突觸間隙內降解逸漏入血COMT兒茶酚胺氧位甲基轉移酶再利用MAO單胺氧化酶降解突觸間隙的遞質消除TURNOVER(更新率)DAisfasterthanthatofNA

(inbrain)-MTinhibitTH:---T1/2(半衰期)ofDAis2h,T1/2ofNAis4h---DAlevelrecovery:1dNAlevelrecovery:4d在不同腦區,DA更新率不同:Caudatenucleus:7.4g/g/hNucleusaccumbens:2-6g/g/hClassificationDistributionMechanismsRECEPTORSAllDAreceptorsareGproteincoupledreceptors:Effector:AC1polypeptidechain7transmembranedomainGpr.coupled

D1family(D1/D1A,D5/D1B)---activationofAC

Gs-coupled

D2family(D2,D3,D4)---inhibitionofAC(D2L,D2S)

Gi/o-coupledClassification（分類）StructureofDopamineReceptors

D1-likereceptorshavealongCOOH-terminalandashort3rdintracellularloop(I3)

D2-likereceptorshaveashortCOOH-terminalandalong3rdintracellularloop(I3)第三胞內環(I3)在受體與G蛋白的偶聯中不起作用（不同于其它的G-蛋白偶聯受體）DA結合位點：TMD-3中Asp103TMD-5中Ser198,199,202跨膜區域（TMD)StructureofD2ReceptorIsoformsTheD2Lreceptorhasanextra29AAinthe3rdintracellularloopandismoreabundantlytranscribedD2Lisbelievedtobethepost-synapticreceptorD2SisbelievedtobethepresynapticautoreceptorD2receptor:

第一個被克隆得到的DA受體（1988）SignalTransductionPathways(信號傳導途徑）ofDopamineReceptorsMechanisms（作用機制）D1ACD1ACGGcAMPPKADARPP-32P-Thr34-DARPP-32Pr.P-Pr.生理作用PP-1DAcAMPPKAP-Thr75-DARPP-32DARPP-32CDK5

活化（如：cocaine濫用時）DARPP-32對D1受體功能的雙向調控作用Dopamineandadenosine-3’5’-monophosphate-regulatedphospho-protein-32Nature.1999Dec9;402(6762):669-71.D1-likeandD2-likereceptorsmayformheteromericcomplexeswitheachotherandwithotherreceptorsDistribution（在中樞神經系統中的分布）D1receptorfamilyD1:striatum,nucleusaccumbens,olfactorytubercle,cortex,hypothalamusstimulationofAC---lowaffinityforDA(micromolar)

（majorisoform)D5:hippocampus,hypothalamusmuchlowerexpressionthanD1stimulationofAC---higheraffinityforDA(submicromolar)大部分腦區，D1與D2共存，但受體密度不同D2receptorfamilyD2:

striatum,nucleusaccumbens,olfactorytubercle,SN,ventraltegmentumincreaseK+conductanceinhibitCa2+entry

autoreceptormajorisoformD3:muchlessabundantthanD2nucleusaccumbens,olfactorytubercle

autoreceptorhighaffinityforDAD4:lessabundantthanD2frontalcortex,midbrain,amygdalahighaffinityforDAAutoreceptors自身受體Autoreceptorstypicallyfunctiontoinhibitthecellsinwhichtheyreside,incellbodiesandinsynapticterminals.TyrDopaNE.............................

2-AR

-ARterminalPostsynaptictargets

2-ARD2RGABABR…D2receptors:autoreceptors（自身受體）Resideinthecellbodies,dendritesandterminusofDAneuronsCellbodyanddendrite:---inhibittheelectricalactivitiesofDAneuronsNerveterminus:---inhibitsynthesisandreleaseofDAAntagonist(拮抗劑）andagonist（激動劑）ofDAreceptorsCentralFunctionsofDA

DA:

Motoractivity,Psychoses,Reward&Reinforcement…Parkinson’sdisease

---withspecificdegenerationofthenigrostriataltract

MotoractivityKatherineHepburnMaoTseTungPopeJohnPaulIIMuhammadAliAdolfHitler

MotoractivityParkinson’sdisease

（黑質多巴胺能神經元的退行性病變

————黑質-紋狀體通路的退化）ImbalanceofDAandAChinPDAChGABA+-DAstriatumAChGABA+-DAstriatumnormalPDDAagonistMuscarinicantagonistL-DOPAadministrationWaitaminute!IfdopamineistoopolartocrosstheBBB,howcanL-DOPAcrossit?Answer!L-DOPAistransportedacrosstheBBBbyanaminoacidtransportsystem(sameoneusedfortyrosineandphenylalanine)Onceacross,L-DOPAisdecarboxylatedtodopaminebyDopaDecarboxylase.Thisisanexampleofa“prodrug.L-DOPAisalmostalwayscoadministeredtogetherwithaninhibitorofaromaticL-aminoaciddecarboxylase.Theinhibitorcommonlyusediscarbidopa,whichdoesnotcrosstheBBBitself.TheinhibitoralsopreventsundesirablesideeffectsofdopaminereleaseintothePNS,includingnausea.WhyisL-DOPAalwayscoadministeredwithcarbidopa?Huntington’sdisease/Huntington’schorea

---紋狀體神經元變性DAactivityenhanced

dyskinesiaGABA等其它種類神經遞質活性的降低

——對黑質多巴胺神經元的抑制性調節減弱

——DA能神經元過度活躍治療：DA受體拮抗劑耗竭CA的藥物（利血平，丁苯那嗪）

MotoractivityAChGABA+-DAstriatumAChGABA+-DAstriatumnormalHDDAantagonistSchizophrenia（精神分裂癥）："dopaminetheoryofschizophrenia"---schizophreniaiscausedbyanoveractivedopaminesysteminthebrain治療：DA受體（D2）拮抗劑（如：氯丙嗪Chlorpromazine等）

Psychoses（參與精神情緒活動）Chlorpromazine(氯丙嗪，冬眠靈):

---D2receptorantagonist（拮抗劑）

---inthetherapyofschizophrenia

（精神分裂癥）

---alsoTardivedyskinesia(TD)！

（遲發性運動障礙）LaiIC，etal.EurJClinPharmacol(2011)67:383–388dyskinesiamayresultfromdivergentchangesi