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extrasynaptic receptors - Coggle Diagram

- - - - spillover
        
        extrasynaptic receptor
      - crosstalk
        
        other synapse
      - other
        
        target glia
    - - non-junctional
    - - limited to specificity and affinity of NTM receptors
    - - 1 to many
    - - slow, 100ms
    - - widespread change in excitability or readiness of the network
    - - ambient NTM
        
        excitatory
        
        glutamate (neuron and glia
        
        inhibitory
        
        GABA (neuron
    - - neuron
        
        spillover
        
        crosstalk
      - glia
    - - by plasma membrane transporters
        
        neuronal
        
        glial
      - by enzymatic degradation
        
        acetylcholinesterase
        
        monoamine oxidase
- - - - GluR
        
        NMDA
        
        electrophysiology
        
        upon binding glutamate, lead to positive current flows if Vmem > -40 mV
        
        results in
        
        EPSP
        
        intracellular CA2+ increase
        
        location
        
        with neural development, the ratio of synap to extrasynap shift
        
        activity-dependent movement
        
        the mobility depends on subunit
        composition or co-agonist binding
        
        NMDA2bR move better
        
        glycine, D-serine
        
        function
        
        hippocampus
        
        Synaptic NMDAR – Support LTP, CREB activation, and cell survival
        Extrasynaptic NMDAR – Support LTD, CREB inactivation, and cell death
        In the intact hippocampus, extrasynaptic NMDARs are probably only activated under pathological conditions
        
        striatum
        
        In slices and in vivo, striatal neurons show up state and down state activity. (to synchronize different brain region)
        Activation of extrasynaptic NMDAR induces
        the excited state
        
        summary
        
        Brain region and cell-type specific
        
        Direction of synaptic plasticity
        
        Activation of distinct intracellular signaling cascades
        
        Developmental & pathological cell survival signal
        
        Different co-agonist binding (synaptic – d-serine, extrasynaptic –glycine
        
        Correlating network up-states
        
        AMPA
        
        kainate
      - GABAaR
        
        subunit composition
        
        2 alpha, 2 beta, 1 gamma or 1 delta
        
        delta
        
        Extrasynaptic location
        
        Higher GABA sensitivity (~10nM)
        
        Non-desensitizing
        
        Smaller and slower currents
        
        electrophysiology
        
        inhibition
        
        phasic
        
        rapid and precise activation of postsynapse
        
        hign concentration of GABA
        
        short inhibiton
        
        tonic
        
        general activation of postsynapse
        
        low, persistent concentration
        
        continuous inhibition
        
        extrasynaptic GABAaR provides low-level tonic inhibition
      - neuromodulatory receptors
        
        nicotinic AchR
        
        electrophysiology
        
        nonselective cation channel
        
        location
        
        mostly hippocampal ACh axons form non-juctional terrminals
        
        pre and post synapse (most of are interneurons
        
        function
        
        nACh alpha 7 help induce LTP of Ca2+ transient influx and EPSPs
        
        Majority of ACh function is extra- or peri/pre-synaptic!
        
        5-HT3
    - - mGluR
        
        location
        
        initiate G protein cascade
        
        found at presynaptic terminal(inhibitory) and postsynaptic (excitatory (can be changed, depending on subtypes
        
        bind 2 glu
        
        electrophysiology
        
        depression of EPSP due to reduce glu release
        
        caused by clock of Ca2+ channels
        
        small effect but longlasting
      - GABAbR
      - neuromodulatory receptors
        
        muscarinic ACh
        
        DA
        
        NE
        
        5-HT