神经生物学：神经元之间的信息传递

1、2013诺贝尔生理学与医学奖授予3名美德科学家 2013年10月07日 2013诺贝尔生理学或医学奖 授予 James E. Rothman, Randy W. Schekman （美国）& Thomas C. Sdhof （德国），以表彰他们在细胞的囊泡运输机制研究中的杰出贡献。神经元之间的信息传递突触传递（Synaptic transmission)突触（Synapse) 电突触 (electric synapse) (少见） 化学突触 (chemical synapse) （主要形式） - through 神经递质（neurotransmitter) Acetylcholine Glut

2、amate GABA Serotonin Noradrenaline Adrenaline Dopamine Histamine 神经递质 特定的化学物质 负责突触处信号的化学 传递Monoamines (单胺类递质)儿茶酚胺 (catecholamine,CA)多巴胺（Dopamine, DA)去甲肾上腺素（ Noradrenaline, norepinephrine, NA或NE)肾上腺素（ adrenaline, epinephrine, A或E)吲哚胺 (indolamine)5-羟色胺（ Serotonine, 5-HT)儿茶酚Serotonin Pathways in CNS Ne

3、urochemistry Receptors Central FunctionsContents1.1 PATHWAYS in CNS cell body location projection pathway1962年， Falk-Hillarp technique(甲醛诱发荧光法)Formaldehyde vapourmonoaminebright-green flurorescence (DA, NE) yellow flurorescence (5-HT)1972年瑞典学者Bjorklund和Lindvail创立了乙醛酸诱发荧光法单胺类神经递质脑内分布的观察手段2. Use of im

4、munofluorescence technique Enzymes，transporters，1. Use of fluorescence histochemistry (Falck & Hillarp)单胺类神经递质脑内分布的观察手段 Major Noradrenergic (blue)去甲肾上腺素, Dopaminergic (red)多巴胺 and Serotonergic (green) 5-羟色胺 Pathways in the CNS A8 (lateral, caudal, dorsal to A9) A9 (substantia nigra, SN 黑质） A10 (vent

5、ral to A9, ventral tegmentum,腹侧被 盖区 ) A12 (arcuate nucleus，弓状核)A8-A10 contains 70% of the DA neurons in the brain Location of DA cell bodies（多巴胺 胞体分布）A8 A10: midbrain 中脑A11A17: diencephalon 间脑A9A10nigrostriatal pathway:黑质-纹状体通路 （运动控制）A8, A9- striatum（纹状体) caudate nucleus（尾核）, putamen（壳核）, amygdala（杏

6、仁核）mesolimbocortical system:中脑-边缘皮质投射 （情感和认知）A10-nucleus accumbent（伏隔核）, olfactory tubercle（嗅结节）, prefrontal（前额叶皮层） and perirhinal cortex（嗅皮层）A9,A10-anterior cingulate cortex(前扣带皮层）tuberoinfundibular system:结节漏斗系统（DA能短投射） A12-pituitary gland（垂体） （抑制垂体分泌激素）下行束脊髓(Spinal cord)（调节躯体和内脏感觉运动） projection p

7、athways of DA neurons （神经投射通路）nigrostriatal pathway:黑质-纹状体通路 （运动控制）A8, A9- striatum（纹状体) caudate nucleus（尾核）, putamen（壳核）, amygdala（杏仁核）mesolimbocortical system:中脑-边缘皮质投射 （情感和认知）A10-nucleus accumbent（伏隔核）, olfactory tubercle（嗅结节）, prefrontal（前额叶皮层） and perirhinal cortex（嗅皮层）A9,A10-anterior cingulate

8、 cortex(前扣带皮层）tuberoinfundibular system:结节漏斗系统（DA能短投射） A12-pituitary gland（垂体） （抑制垂体分泌激素）下行束脊髓(Spinal cord)（调节躯体和内脏感觉运动） projection pathways of DA neurons （神经投射通路）nigrostriatal pathway:黑质-纹状体通路 （运动控制）A8, A9- striatum（纹状体) caudate nucleus（尾核）, putamen（壳核）, amygdala（杏仁核）mesolimbocortical system:中脑-边缘皮

9、质投射 （情感和认知）A10-nucleus accumbent（伏隔核）, olfactory tubercle（嗅结节）, prefrontal（前额叶皮层） and perirhinal cortex（嗅皮层）A9,A10-anterior cingulate cortex(前扣带皮层）tuberoinfundibular system:结节漏斗系统（DA能短投射） A12-pituitary gland（垂体） （抑制垂体分泌激素）下行束脊髓(Spinal cord)（调节躯体和内脏感觉运动） projection pathways of DA neurons （神经投射通路）nigr

10、ostriatal pathway:黑质-纹状体通路 （运动控制）A8, A9- striatum（纹状体) caudate nucleus（尾核）, putamen（壳核）, amygdala（杏仁核）mesolimbocortical system:中脑-边缘皮质投射 （情感和认知）A10-nucleus accumbent（伏隔核）, olfactory tubercle（嗅结节）, prefrontal（前额叶皮层） and perirhinal cortex（嗅皮层）A9,A10-anterior cingulate cortex(前扣带皮层）tuberoinfundibular s

11、ystem:结节漏斗系统（DA能短投射） A12-pituitary gland（垂体） （抑制垂体分泌激素）下行束脊髓(Spinal cord)（调节躯体和内脏感觉运动） projection pathways of DA neurons （神经投射通路） locus coeruleus (LC 蓝斑) complex -A4,A6 lateral tegmental nuclei 外侧被盖核 -A1,A3,A5,A7,A2 Location of NA cell bodies（去甲肾上腺素能神经元-胞体分布）A1 A7: Pons、medulla 脑桥、延髓LC Projection pa

12、thways of NE neuronsThe locus coeruleus complexLateral tegmental nucleiCerebral cortex HippocampusBrainstem nuclei (sensory)Spinal cordCerebellum ThalamusHypothalamusAmygdala SeptumBrainstem nuclei (motor)Hypothalamus (all nuclei)Frontal cortexOlfactory bulbparaventricular nucleus suprachiasmatic nu

13、cleus蓝斑复合体视交叉上核Noradrenaline pathways in rat brain Synthesis Storage Release Eliminate Reuptake Metabolism1.2 NEUROCHEMISTRYDA/NEDopamineVesiclesynthesisstoragereleasereceptoreliminationreuptakemetabolism神经递质的Neurochemistry 示意图Enzymes: tyrosine hydroxylase(TH, 酪氨酸羟化酶）Dopa decarboxylase(DDC, 多巴脱羧酶）SY

14、NTHESIS (合成）DA and NA synthesis are SimilarPrecursor: tyrosine(酪氨酸）Synthesis for DA in cytoplasm of CA neurons （儿茶酚胺能神经元） Synthesis for NA in vesicles of NA neurons（NA 神经元囊泡）Dopamine-hydroxylase (DH) SYNTHESIS NA DAPrecursor:Tyrosine (tyr) tyrEnzymes: tyrosine hydroxylase (TH)* TH*Dopa decarboxylase

15、 (DDC) DDCDopamine-hydroxylase (DH)Cytosol and vesicle cytosolNAergic neurons DAergic SYNTHESIS* rate-limiting enzyme SYNTHESISThe enzymes involved:Tyrosine hydroxylase (TH, 酪氨酸羟化酶）Dopa decarboxylase (DDC, 多巴脱羧酶）Dopamine-hydroxylase (DH,多巴胺羟化酶) SYNTHESISTyrosine hydroxylase (TH, 酪氨酸羟化酶）Cytoplasmic e

16、nzyme： tyrL-dopa Km=510-6 M 脑内色氨酸Fe2+,O2, and tetrahydropterine (BH4)Substrate-specificInhibitors: desferrioxamine(去铁草酰胺); dopamine; PCPATrp: rate-limiting factor!TrpbloodBBBbrainLNAA carriers: large neutral amino acids carriers （大分子中性氨基酸转运体：for Trp, Phe, Leu, Ile, Val 转运）TrpTPH正常情况下，脑内TPH远未饱和Neuroc

17、hemistry of Serotonindietary availabilityFM&Q Fig 9.4FM&Q Fig 9.5high carbo (碳水化合物） and low protein diet is best for increasing 5-HT. SYNTHESIS5-HTP decarboxylase (5-羟色氨酸脱羧酶)soluble enzyme： 5-hydroxytryptophan 5-HTKm=10 MSubstrate-specificL-aromatic amino acid decarboxylase (AADC) the same enzyme in

18、volved in the biosynthesis of catecholamines SYNTHESISControl of 5-HT synthesis1, brain Trp level- rate-limiting factor2, brain 5-HT level- negative feedback3, TPH （色氨酸羟化酶） rapid: activity slow: expressionEvidence:Neuronal depolarization phosphorylation:Neuronal depolarization TPH activation Ca2+/ca

19、lmodulin-dependent protein kinase inhibitorPhosphorylation of TPH -an increase in activity Ca2+/calmodulin-dependent protein kinase II cAMP-dependent protein kinase (PKA) SYNTHESIS2.2 STORAGE (储存） Vesicular storage (30-35 mm diameter) （囊泡储存） Vesicles containing serotonin-binding proteins (SBP), form

20、 a macromolecular complex with 5-HT SBP can be secreted into the synapse along with 5-HT VMAT （囊泡单胺转运体）： 质子泵产生的 H+ 梯度作为能量 STORAGE2.3 RELEASE （释放） 胞裂外排 （exocytosis) Autoreceptors suppress 5-HT release: 5-HT1A receptors: on the cell bodies of neurons in the Raphe nuclei ; 5-HT1B/1D receptors: on their

21、 terminals Heteroceptors modify 5-HT release: nAChR: increase release from striatal synaptosomes; 2A adrenoceptors: depress cortical release Releasing agent: fenfluramine2.4 REUPTAKE （重摄取）serotonin transporter (SERT) Na+/Cl- dependent transporterSERT has large number of potential phosphorylation sit

22、es and can be phosphorylated by PKA and PKC. In vitro SERT phosphorylation by PKC leads to the internalization of the protein and to a reduction in serotonin reuptake.“uptake-1” and “uptake-2”.FM&Q Fig 9.1Dependent on Na+ and Cl- bindingNa+ and Cl- are brought into the cell along with 5-HT and K+ is

23、 extrudedDrugs that block 5-HT reuptake bind to the 5-HT binding siteEnergy supplied by Na+/K+ dependent ATPasePhosphorylation of SERTAt least 8 phosphorylation siteRapid, short-term regulationPKA, PKC: internalization (decrease the reuptake of 5-HT)Inhibitors of 5-HT transporter (SERT) TCA（Tricycli

24、c antidepressants，三环类抗抑郁药）: clomipramine(氯丙咪嗪)， Selective serotonin reuptake inhibitor (SSRIs): fluoxetine, sertraline, fluvoxamine, paroxetine, citalopram Cocaine （可卡因） Amphetamine （安非他命） Fenfluramine（芬弗拉明）(DAT, SERT) MDMA（ecstasy，摇头丸）：neurotoxin for 5-HT neuron(similar to the effect of MPTP on DA

25、neuron) （SERT底物，刺激脑部快速释放大量的5-HT）2.5 METABOLISM （酶解失活）MAOA- CHO- COOH5-HT 5-HIAA（5-羟吲哚乙酸）醛脱氢酶MOAI（-）NCNCNH2COOHCOOHNH2OHNCNH2OHHTryptophan5-Hydroxytryptophan5-HydroxytryptamineNCCOOH5-OH Indole Acetaldehyde5-Hydroxy Indole Acetic AcidTryptophan hydroxylase5-OH Tryptophan decarboxylaseMAOAldehyde dehy

26、drogenase(Rate limiting)In diet. ActiveCNS transport 7 distinct families 14 distinct subtypes have been cloned so far3. RECEPTORS（5-HT受体）The pharmacology of 5-HT is extremely complex, with its actions being mediated by a large and diverse range of 5-HT receptors - many of which have poorly character

27、ised physiological functions.All are G protein coupled receptors except 5-HT3 5-HT3 : ligand-gated ion channels: 5-HT3A， 5-HT3B， 5-HT3CSplice variants: 5-HT3, 5-HT4 , 5-ht6, 5-HT7 RNA edited isoforms: 5-HT2C Different central distribution and function5HT1A: role in anxiety/depression5HT1D: role in m

28、igraine5HT2: role in CNS various behaviors, and in cardiovascular system5-HT3: role in nausea and vomiting esp. due to Chemotherapy.5-HT1A: hippocampus, septum, amygdala, dorsal raphe, cortex5-HT1B: substantia nigra, basal ganglia5-HT1D: substantia nigra, striatum, accumbens, hippocampus less than 5

29、-HT1B5-ht1E, 5-ht1F： lack of specific ligands 5-HT1A receptors: somatodendritic autoreceptors reside on serotonergic cell bodies and dendrites reduce cell firing and curtails the synthesis and release of 5-HT 5-HT1B/1D receptors: reside on presynaptic nerve terminal decrease the local synthesis and

30、release of 5-HTAutoreceptors on somatodendrites and terminals5-HT2A: cortex, olfactory tubercle, claustrum5-HT2B: not located in brain (lack of specific ligands)5-HT2C: basal ganglia, choroid plexus, substantia nigra5-HT3 receptor: Spinal cord, cortex, hippocampus, brain stem nucleia ligand-gated io

31、n channel that is homologous to other receptor ionophores.nonselective cation channel; triggers a rapid, transient depolarizing current that is carried by Na+ and K+.5-HT4: hippocampus, nucleus accumbens, striatum, substantia nigra5-ht5A: cortex, hippocampus, cerebellum5-ht5B: hippocampus5-ht6: stri

32、atum, olfactory tubercle, cortex, hippocampus5-HT7: hypothalamus, thalamus, cortex, suprachiasmatic nucleusSerotonin Agonists （受体激动剂）Sumatriptan(舒马曲坦): 5-HT1D agonist; antimigraineBuspirone(丁螺环酮) : 5-HT1A agonist for anxietyCisapride(西沙比利): 5-HT4 agonist to GI motility and decrease GE reflux (Remove

33、d from US market due to fatal arrhythmias)LSD: 5HT1A agonist hallucinogen(致幻剂)Serotonin Antagonists（受体拮抗剂）Methysergide（二甲麦角新碱） and Cyproheptadine（赛庚啶）: 5HT2 antagonists. In carcinoid, migraine. Ketanserin（酮舍林,凯坦生）: 5HT2 and Alpha antagonist used as antihypertensive.Ondansetron（奥坦西隆）: 5-HT3 antagonis

34、t for chemotherapy induced nausea and vomitingClozapine（氯氮平）: 5HT2A/2C antagonist: for schizophrenia.Interference with 5-HT systema shift back to less selective compoundsInterference with 5-HT system Levels of serotonin in the brain can be manipulated by:Inhibit tryptophan uptake into CNS: exclusion

35、 of tryptophan from the dietInhibit synthesis: p-chlorophenylalanine (irreversible) （TH）Inhibit neuronal re-uptake: cocaine, SSRI (e.g. fluoxetine), TCA (e.g. imipramine丙咪嗪)Inhibit storage-deplete: reserpineInhibit metabolism: MAO inhibitorsPromote release: p-chloroamphetamine - then depletes (e.g.

36、fenfluramine to appetite)Neurotoxins:5,6-DHT/5,7-DHTNon-selectiveAlthough serotonin can mediate numerous therapeutic actions, too much serotonin can cause dangerous toxicity. The blind men and the elephant. 5-HT, 5-hydroxytryptamine or serotonin;CBF, cerebral blood flow; GI, gastrointestinal. Figure

37、 adapted from a woodblock print by Katsushika Hokusai (17601849).4. CENTRAL FUNCTIONS Pain perception （projection from inferior group neurons to spinal cord) Sleep/Wakefulness Various behaviors normal/abnormal: depression, schizophrenia, obsessive compulsive behavior, etc. DepressionOld Man with his

38、 Head in his HandsVan Gogh, 1882 Depression Catecholamine HypothesisFifteen percent of individuals prescribed reserpine for hypertension developed depression.MAOIs being prescribed for tuberculosis (肺结核） were found to elevate mood.Cocaine and amphetamine, which increase catacholamines, elevate mood.

39、NE is found in abundance in the limbic systems（大脑边缘系）and is thought to regulate mood.Depressed individuals show low levels of MHPG, a metabolite of NE.Tricyclic antidepressant drugs were found to inhibit the reuptake of NE.(抑郁症可能与CA的功能不足/降低有关）Problems with the Catacholamine HypothesisTryicyclic anti

40、depressant drugs required several days or weeks to alleviate the symptoms of depression.Healthy individuals did not show elevated mood with tricyclic antidepressants.Cocaine and amphetamine are not good antidepressants.Non-tricylcic antidepressants that specifically affected 5-HT were found to be cl

41、inically affective in alleviating the symptoms of depression.Depression - Serotonin Hypothesis (抑郁症可能与5-HT的功能不足/降低有关）The most clinically effective antidepressants are those that are most selective for reuptake of 5-HT (SSRIs).The data that previously were taken in support of the catacholamine hypoth

42、esis could also support the role of 5-HT because reserpine, MAOIs and tricyclics also affect 5-HT.But the effects of SSRIs also take days or weeks even though the biochemical action on 5-HT reuptake is immediate. Depression - Support for the Serotonin HypothesisDepressed individuals have:Lower level

43、s of plasma tryptophan.Lower CSF levels of 5HIAA.Decreased platelet （血小板）5-HT uptake suggesting lower levels of 5-HT release.Blunted responsiveness to serotonin agonist challenge suggesting decreased 5-HT responsiveness.Specific Treatments for DepressionAll effective antidepressants act by increasin

44、g the activity of one or both of these neurotransmitter systemsBlock neurotransmitter reuptake systemsSerotonin Re-uptake inhibitors (SSRIs) Tricyclic antidepressants (TCAs)Block neuronal metabolism and so increase amount releasedMonoamine Oxidase Inhibitors (MAOIs)Increase amount of neurotransmitte

45、r releasedPresynaptic autoreceptor blockadeElectroconvulsive Therapy (ECT)More effective than drug therapiesRapid therapeutic effect (1-2 weeks vs 4-6 weeks for other therapies)Minimal adverse effectsPossible Sites of Antidepressant Drug Action Monoamine Oxidase InhibitorsAutoreceptor AntagonistsMir

46、tazepineRe-Uptake InhibitorsSSRIsTCAs Requirments1）Pathways and distribution of DA,NA and 5-HT in CNS (Substantia nigra, locus coeruleus, or raphe nucleus)2）Neurochemistry of DA,NA and 5-HT synthesis（enzymes and regulation factors: TH, DDC, DbH; TPH, 5-HTPDC; Rate-limiting enzyme） storage (Vesicle,

47、VMAT; H+ dependent transporter; Reserpine) release reuptake (DAT, NET, SERT, Na+/Cl- dependent transporter; Cocaine, amphetamine, TCAs, SSRIs, MPTP, 6-OHDA) metabolism (MAO, COMT, MAOI )3）Receptors of DA,NA and 5-HT Classification (D1D5; a1, a2, b; 5HT1.5HT7 receptors; autoreceptors) mechanisms (ago

48、nist, antagonist)4） Central function DA & Parkinsons disease (PD) DA & Schizophrenia Monoamines (NA & 5-HT) & Depression 谢 谢！ Roberto Maggio1 and Mark J Millan, Current Opinion in Pharmacology 2010, 10:100107Homomers: D2D2 Heteromers: D2D3, D1/D5, D2/D3/D4, 磷酸化的DARPP-32是蛋白磷酸酯酶-I (PP1)的强大抑制剂，阻止PP1的去磷

49、酸化作用，使生理效应增强。其重要生理意义：1，DARPP-32达到最大半数抑制效应时，所需的浓度极低（10nmol/L），而在神经元侧棘中DARPP-32的浓度比上述抑制作用浓度高1000-5000倍；2，其 抑制作用完全依赖于分子结构中Thr 34 的磷酸化，一旦被去磷酸化，抑制作用随之解除；3，脑内只有磷酸酯酶-I受到磷酸化的DARPP-32的抑制，故有极好的选择性，增强D1受体的生理效应，放大D1受体的作用。4,磷酸化的DARPP-32本身被蛋白磷酸酯酶2B去磷酸化后，则失去抑制磷酸酯酶I的作用。Regulation of DARPP-32 phosphorylation by four

50、kinases and three phosphatasesNeuropharmacology 47 (2004) 1423；Cell. Mol. Life Sci. 65 (2008) 2125 2127学生课后提问-2012-10 ：华山医院神经内科一学生：他们拟用影像学方法标记和检测人脑黑质（LC）中的VMAT，用于分析LC脑区DA neuron 在不同病程阶段 PD病人的特征。 此时，黑质中的 NA，或5-HT 神经元（其中同样也包含 VMAT ）是否会对其分析产生影响？学生课后提问-2011-10 ：已知PKC对 TH的 Ser 40 磷酸化有促进作用，并增强其活性。 但在随后的论文介绍中， PKC-delta 却是通过增强PP2B 的磷酸化和活性，从而抑制TH 活性的。 那么， PKC-delta 究竟是否也能通过直接磷酸化TH的Ser40 从而增强其活性，只是该途径的效应要小于 PP2B 途径 ？（从而使总的效应是： PKC-delta 降低TH 磷