The toxicity of amyloid-beta（Aβ） is strongly associated with Alzheimer’s disease（AD）,which has a high incidence in the elderly worldwide.Recent evidence showed that alteration in the activity of N-methyl-D-aspar...The toxicity of amyloid-beta（Aβ） is strongly associated with Alzheimer’s disease（AD）,which has a high incidence in the elderly worldwide.Recent evidence showed that alteration in the activity of N-methyl-D-aspartate receptors（NMDARs） plays a key role in Aβ-induced neurotoxicity.However,the activation of synaptic and extrasynaptic NMDARs has distinct consequences for plasticity,gene regulation,neuronal death,and Aβ production.This review focuses on the dysregulation of synaptic and extrasynaptic NMDARs induced by Aβ.On one hand,Aβ downregulates the synaptic NMDAR response by promoting NMDAR endocytosis,leading to either neurotoxicity or neuroprotection.On the other hand,Aβ enhances the activation of extrasynaptic NMDARs by decreasing neuronal glutamate uptake and inducing glutamate spillover,subsequently causing neurotoxicity.In addition,selective enhancement of synaptic activity by low doses of NMDA,or reduction of extrasynaptic activity by memantine,a non-competitive NMDAR antagonist,halts Aβ-induced neurotoxicity.Therefore,future neuroprotective drugs for AD should aim at both the enhancement of synaptic activity and the disruption of extrasynaptic NMDAR-dependent death signaling.展开更多
Most hypotheses concerning the mechanisms underlying Parkinson＇s disease are based on altered synaptic transmission of the nigrostriatal system. However, extrasynaptic transmission was recently found to affect dopami...Most hypotheses concerning the mechanisms underlying Parkinson＇s disease are based on altered synaptic transmission of the nigrostriatal system. However, extrasynaptic transmission was recently found to affect dopamine neurotransmitter delivery by anisotropic diffusion in the extracellular matrix which is modulated by various extracellular matrix components such as flbronectin. The present study reviewed the neuroprotective effect of fibronectin in extrasynaptic transmission. Fibronectin can regulate neuroactive substance diffusion and receptor activation, and exert anti- neuroinflammatory, adhesive and neuroprotective roles. Fibronectin can bind to integrin and growth factor receptors to transactivate intracellular signaling events such as the phosphatidylinositol 3-kinase/protein kinase B pathway to regulate or amplify growth factor-like neuroprotective actions. Fibronectin is assembled into a fibrillar network around cells to facilitate cell migration, molecule and ion diffusion, and even drug delivery and treatment. In addition, the present study analyzed the neuroprotective mechanism of fibronectin in the pathogenesis of Parkinson＇s disease, involving integrin and growth factor receptor interactions, and discussed the possible therapeutic and diagnostic significance of fibronectin in Parkinson＇s disease.展开更多
Activation of N-methyl-D-aspartate receptors（NMDARs）mediates changes in the phosphorylation status of the glutamate receptors themselves.Previous studies have indicated that during synaptic activity,tyrosine kinases...Activation of N-methyl-D-aspartate receptors（NMDARs）mediates changes in the phosphorylation status of the glutamate receptors themselves.Previous studies have indicated that during synaptic activity,tyrosine kinases（Src and Fyn）or phosphatases（PTPαand STEP）are involved in regulating the phosphorylation of NMDARs.In this study,we used immunoblotting to investigate the role of an NMDAR subpopulation on the phosphorylation level of the GluN2B subunit at the Y1336 and Y1472sites in rat brain slices after NMDA treatment.We found that NMDA stimulation dramatically decreased the phosphorylation level of GluN2B at Y1472 in a dose-and time-dependent manner,but not at Y1336.Extrasynaptic NMDAR activation did not reduce the phosphorylation of GluN2B at Y1472.In addition,ifenprodil,a selective antagonist of GluN2Bcontaining NMDARs,did not abolish the decreased phosphorylation of GluN2B at Y1472 triggered by NMDA.These results suggest that the activation of synaptic GluN2A-containing NMDARs is required for the decreased phosphorylation of GluN2B at Y1472that is induced by NMDA treatment in rat brain slices.展开更多
γ-Aminobutyric acid（GABA）,plays a key role in all stages of life,also is considered the main inhibitory neurotransmitter.GABA activates two kind of membrane receptors known as GABAA and GABAB,the first one is respo...γ-Aminobutyric acid（GABA）,plays a key role in all stages of life,also is considered the main inhibitory neurotransmitter.GABA activates two kind of membrane receptors known as GABAA and GABAB,the first one is responsible to render tonic inhibition by pentameric receptors containing α4-6,β3,δ,or ρ1-3 subunits,they are located at perisynaptic and/or in extrasynaptic regions.The biophysical properties of GABAA tonic inhibition have been related with cellular protection against excitotoxic injury and cell death in presence of excessive excitation.On this basis,GABAA tonic inhibition has been proposed as a potential target for therapeutic intervention of Huntington＇s disease.Huntington＇s disease is a neurodegenerative disorder caused by a genetic mutation of the huntingtin protein.For experimental studies of Huntington＇s disease mouse models have been developed,such as R6/1,R6/2,Hdh Q92,Hdh Q150,as well as YAC128.In all of them,some key experimental reports are focused on neostriatum.The neostriatum is considered as the most important connection between cerebral cortex and basal ganglia structures,its cytology display two pathways called direct and indirect constituted by medium sized spiny neurons expressing dopamine D1 and D2 receptors respectively,they display strong expression of many types of GABAA receptors,including tonic subunits.The studies about of GABAA tonic subunits and Huntington＇s disease into the neostriatum are rising in recent years,suggesting interesting changes in their expression and localization which can be used as a strategy to delay the cellular damage caused by the imbalance between excitation and inhibition,a hallmark of Huntington＇s disease.展开更多
Volume transmission （VT） is a widespread mode of intercellular communication that occurs in the extracellular fluid （ECF） and in the cerebrospinal fluid （CSF） of the brain with VI signals moving from source to t...Volume transmission （VT） is a widespread mode of intercellular communication that occurs in the extracellular fluid （ECF） and in the cerebrospinal fluid （CSF） of the brain with VI signals moving from source to target cells via energy gradients leading to diffusion and convection （flow）. The VT channels are diffuse forming a plexus in the extracellular space, while in wiring transmission （WT） the channels （axons, terminals） are private. The speed is slow （seconds-minutes） in VT while rapid in the millisecond range in w-r. The extracellular space is the substrate for VT, which is modulated by the extracellular matrix. Extrasynaptic VT is linked to synaptic transmission and likely often takes place due to incomplete diffusion barriers with the synaptic transmitter reaching extrasynaptic domains of the pre-and post-synaptic membrane of the synapse, the astroglia, and even adjacent synapses. Indications exist for the existence of striatal D2-1ike receptor-mediated extrasynaptic form of dopamine （DA） VT at the local circuit level in vivo in the human striatum. Synaptic glutamate via extrasynaptic VT can act on extrasynaptic metabotropic glutamate receptors located on the astroglia leading to Ca2~ mediated astrocytic glutamate release into the extracellular space （ECS）. Long distance peptide VT and CSF VT is the major long distance VT with distances more than 1 mm and flow in the CSF. Indications for long distance vr of beta-endorphin and oxytocin are obtained. We propose that monogamy in the female prairie vole may take place through an increase in oxytocin v-r, especially in nucleus accumbens. Release of extracellular vesicles containing receptors, proteins, RNAs and mtDNA from cellular networks in the central nervous system （CNS） into the ECF and CSF may be a fundamental communication in the CNS. It represents a special form of volume transmission, the Roamer subtype of VT. It may greatly contribute to dynamic events of synaptic plasticity but also to spread of pathological proteins in protein conformational disorders. V＇i＂ also occurs in the peripheral nervous system and associated cells. Short and long distance VT may take place in meridian channels via diffusion and flow in the interstitial fluid. Acupuncture can produce VT signals by releasing transmitters and modulators from nerve terminals and mast cells.展开更多
基金supported by the National Natural Science Foundation of China(81371223 and 81371437)the Research Fund for the Doctoral Program of Higher Education of China(20122105110010)the Science and Technology Project of Liaoning Province,China(2011226006)
文摘The toxicity of amyloid-beta（Aβ） is strongly associated with Alzheimer’s disease（AD）,which has a high incidence in the elderly worldwide.Recent evidence showed that alteration in the activity of N-methyl-D-aspartate receptors（NMDARs） plays a key role in Aβ-induced neurotoxicity.However,the activation of synaptic and extrasynaptic NMDARs has distinct consequences for plasticity,gene regulation,neuronal death,and Aβ production.This review focuses on the dysregulation of synaptic and extrasynaptic NMDARs induced by Aβ.On one hand,Aβ downregulates the synaptic NMDAR response by promoting NMDAR endocytosis,leading to either neurotoxicity or neuroprotection.On the other hand,Aβ enhances the activation of extrasynaptic NMDARs by decreasing neuronal glutamate uptake and inducing glutamate spillover,subsequently causing neurotoxicity.In addition,selective enhancement of synaptic activity by low doses of NMDA,or reduction of extrasynaptic activity by memantine,a non-competitive NMDAR antagonist,halts Aβ-induced neurotoxicity.Therefore,future neuroprotective drugs for AD should aim at both the enhancement of synaptic activity and the disruption of extrasynaptic NMDAR-dependent death signaling.
基金supported by a grant from the National Science and Technology Infrastructure Platform,Ministry of Science and Technology,No. 2005DKA32400
文摘Most hypotheses concerning the mechanisms underlying Parkinson＇s disease are based on altered synaptic transmission of the nigrostriatal system. However, extrasynaptic transmission was recently found to affect dopamine neurotransmitter delivery by anisotropic diffusion in the extracellular matrix which is modulated by various extracellular matrix components such as flbronectin. The present study reviewed the neuroprotective effect of fibronectin in extrasynaptic transmission. Fibronectin can regulate neuroactive substance diffusion and receptor activation, and exert anti- neuroinflammatory, adhesive and neuroprotective roles. Fibronectin can bind to integrin and growth factor receptors to transactivate intracellular signaling events such as the phosphatidylinositol 3-kinase/protein kinase B pathway to regulate or amplify growth factor-like neuroprotective actions. Fibronectin is assembled into a fibrillar network around cells to facilitate cell migration, molecule and ion diffusion, and even drug delivery and treatment. In addition, the present study analyzed the neuroprotective mechanism of fibronectin in the pathogenesis of Parkinson＇s disease, involving integrin and growth factor receptor interactions, and discussed the possible therapeutic and diagnostic significance of fibronectin in Parkinson＇s disease.
基金supported by grants from the National Natural Science Foundation of China (30900418)the Natural Science Program of Department of Education of Zhejiang Province,China (Y201122469)
文摘Activation of N-methyl-D-aspartate receptors（NMDARs）mediates changes in the phosphorylation status of the glutamate receptors themselves.Previous studies have indicated that during synaptic activity,tyrosine kinases（Src and Fyn）or phosphatases（PTPαand STEP）are involved in regulating the phosphorylation of NMDARs.In this study,we used immunoblotting to investigate the role of an NMDAR subpopulation on the phosphorylation level of the GluN2B subunit at the Y1336 and Y1472sites in rat brain slices after NMDA treatment.We found that NMDA stimulation dramatically decreased the phosphorylation level of GluN2B at Y1472 in a dose-and time-dependent manner,but not at Y1336.Extrasynaptic NMDAR activation did not reduce the phosphorylation of GluN2B at Y1472.In addition,ifenprodil,a selective antagonist of GluN2Bcontaining NMDARs,did not abolish the decreased phosphorylation of GluN2B at Y1472 triggered by NMDA.These results suggest that the activation of synaptic GluN2A-containing NMDARs is required for the decreased phosphorylation of GluN2B at Y1472that is induced by NMDA treatment in rat brain slices.
基金the programs for the postdoctoral fellowships-Chilean CONICYT-FONDECYT#3140218,Mexican CONACYT#164978 and DID-UACh S-2015-81Sistema Nacional de Investigadores#58512 to Abraham Rosas-Arellano+2 种基金supported by USACH PhD fellowshipsupported with a PhD fellowship from CONACYT(#299627)FONDECYT grants 1151206 and 1110571 to Maite A.Castro
文摘γ-Aminobutyric acid（GABA）,plays a key role in all stages of life,also is considered the main inhibitory neurotransmitter.GABA activates two kind of membrane receptors known as GABAA and GABAB,the first one is responsible to render tonic inhibition by pentameric receptors containing α4-6,β3,δ,or ρ1-3 subunits,they are located at perisynaptic and/or in extrasynaptic regions.The biophysical properties of GABAA tonic inhibition have been related with cellular protection against excitotoxic injury and cell death in presence of excessive excitation.On this basis,GABAA tonic inhibition has been proposed as a potential target for therapeutic intervention of Huntington＇s disease.Huntington＇s disease is a neurodegenerative disorder caused by a genetic mutation of the huntingtin protein.For experimental studies of Huntington＇s disease mouse models have been developed,such as R6/1,R6/2,Hdh Q92,Hdh Q150,as well as YAC128.In all of them,some key experimental reports are focused on neostriatum.The neostriatum is considered as the most important connection between cerebral cortex and basal ganglia structures,its cytology display two pathways called direct and indirect constituted by medium sized spiny neurons expressing dopamine D1 and D2 receptors respectively,they display strong expression of many types of GABAA receptors,including tonic subunits.The studies about of GABAA tonic subunits and Huntington＇s disease into the neostriatum are rising in recent years,suggesting interesting changes in their expression and localization which can be used as a strategy to delay the cellular damage caused by the imbalance between excitation and inhibition,a hallmark of Huntington＇s disease.
基金Supported by grants from the Swedish Research Council (04X-715)Torsten and Ragnar Sderberg Foundation, Hjrnfonden and Marianne and Marcus Wallenberg Foundation to KF,by a grants from the Swedish Royal Academy of Sciences and Karolinska Institutet Forskningsstiftelser 2012 to DOB-E
文摘Volume transmission （VT） is a widespread mode of intercellular communication that occurs in the extracellular fluid （ECF） and in the cerebrospinal fluid （CSF） of the brain with VI signals moving from source to target cells via energy gradients leading to diffusion and convection （flow）. The VT channels are diffuse forming a plexus in the extracellular space, while in wiring transmission （WT） the channels （axons, terminals） are private. The speed is slow （seconds-minutes） in VT while rapid in the millisecond range in w-r. The extracellular space is the substrate for VT, which is modulated by the extracellular matrix. Extrasynaptic VT is linked to synaptic transmission and likely often takes place due to incomplete diffusion barriers with the synaptic transmitter reaching extrasynaptic domains of the pre-and post-synaptic membrane of the synapse, the astroglia, and even adjacent synapses. Indications exist for the existence of striatal D2-1ike receptor-mediated extrasynaptic form of dopamine （DA） VT at the local circuit level in vivo in the human striatum. Synaptic glutamate via extrasynaptic VT can act on extrasynaptic metabotropic glutamate receptors located on the astroglia leading to Ca2~ mediated astrocytic glutamate release into the extracellular space （ECS）. Long distance peptide VT and CSF VT is the major long distance VT with distances more than 1 mm and flow in the CSF. Indications for long distance vr of beta-endorphin and oxytocin are obtained. We propose that monogamy in the female prairie vole may take place through an increase in oxytocin v-r, especially in nucleus accumbens. Release of extracellular vesicles containing receptors, proteins, RNAs and mtDNA from cellular networks in the central nervous system （CNS） into the ECF and CSF may be a fundamental communication in the CNS. It represents a special form of volume transmission, the Roamer subtype of VT. It may greatly contribute to dynamic events of synaptic plasticity but also to spread of pathological proteins in protein conformational disorders. V＇i＂ also occurs in the peripheral nervous system and associated cells. Short and long distance VT may take place in meridian channels via diffusion and flow in the interstitial fluid. Acupuncture can produce VT signals by releasing transmitters and modulators from nerve terminals and mast cells.
