Disentangling astroglial physiology with a realistic cell model in silico (Savtchenko et al 2018)

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Accession:243508
"Electrically non-excitable astroglia take up neurotransmitters, buffer extracellular K+ and generate Ca2+ signals that release molecular regulators of neural circuitry. The underlying machinery remains enigmatic, mainly because the sponge-like astrocyte morphology has been difficult to access experimentally or explore theoretically. Here, we systematically incorporate multi-scale, tri-dimensional astroglial architecture into a realistic multi-compartmental cell model, which we constrain by empirical tests and integrate into the NEURON computational biophysical environment. This approach is implemented as a flexible astrocyte-model builder ASTRO. As a proof-of-concept, we explore an in silico astrocyte to evaluate basic cell physiology features inaccessible experimentally. ..."
Reference:
1 . Savtchenko LP, Bard L, Jensen TP, Reynolds JP, Kraev I, Medvedev N, Stewart MG, Henneberger C, Rusakov DA (2018) Disentangling astroglial physiology with a realistic cell model in silico. Nat Commun 9:3554 [PubMed]
Model Information (Click on a link to find other models with that property)
Model Type: Glia;
Brain Region(s)/Organism: Hippocampus;
Cell Type(s): Astrocyte;
Channel(s): I Calcium; I Potassium; Kir;
Gap Junctions: Gap junctions;
Receptor(s):
Gene(s):
Transmitter(s): Glutamate;
Simulation Environment: NEURON; MATLAB; C or C++ program;
Model Concept(s): Calcium waves; Calcium dynamics; Potassium buffering; Volume transmission; Membrane Properties;
Implementer(s): Savtchenko, Leonid P [leonid.savtchenko at ucl.ac.uk];
Search NeuronDB for information about:  I Calcium; I Potassium; Kir; Glutamate;
load_file("nrngui.hoc")
load_file("CellInit.hoc")
load_file("CellUpdate.hoc")
load_file("MechanismSwitch.hoc")
load_file("MainUi.hoc")
load_file("GeometricalParameters.hoc")
load_file("Simulations/SimFrapInCircleGeometry.hoc")
load_file("Simulations/SimFrapLine.hoc")
load_file("Simulations/SimSpatialVoltageDistributions.hoc")
load_file("Simulations/SimConstantElectricalSimulations.hoc")
load_file("Simulations/SimFrequencyElectricalSimulation.hoc")
load_file("Simulations/SimCalciumDynamics.hoc")
load_file("Simulations/SimCalciumWave.hoc")
load_file("Simulations/SimGlutamate.hoc")
load_file("Simulations/SimPotassium.hoc")

// Sets initial params.
proc initParamsMain() {
    GapResistance = 100000          // Megaohm
    potential = -85                 // mV
    res_gap(GapResistance, potential)

    Z_coordinate = 10   // the stochastic parameter changes the Z-distribution of astrocytes branches 
    ScalingDiam = 0.127 //  the parameter scales the diameter of the central dendrites
	
	LengthXY = 5.5
	LengthZ =2
	ShiftXY=200
	Distance=2
	jd = 0
    SwitchOffGapJunction=1	
	
     if (ScaleGeometryParameters==1) {
	 stretch(Z_coordinate, ScalingDiam)
	 } else {
	     // stretchXY( LengthXY, LengthZ, ShiftXY)
		  }
	//
   
    // This parameter defines how fast calcium relaxes between neighboring astrocytes.
    // The larger value means a slower connection between astrocytes.
  
	//***************************************************************************************
     insertGapJunc()
     CaGapFlux(jd, SwitchOffGapJunction)
	//*************************************************************************************** 
    InsertElectricMechanisms(1)
    DensityGluTransporters = 1e12   				 // 1/um2
    MaxDimLeaves = 2.5             					 // um
    MinDimLeaves = 0.1             					 // um
    MaxLenLeaves = 0.12            					 // um
    MinLenLeaves = 0.1             					 // um
	GPassive = 0.001 								 // Ohm cm
    setLeaves(MaxDimLeaves, MinDimLeaves, MaxLenLeaves, MinLenLeaves, nanoDistrLoaded, DensityGluTransporters, GPassive)
    
    MaxDimStalk = 0.1                               // um
    MinDimStalk = 0.1                               // um
    MaxLenStalk = 1*12/NumberLeaves                 // um
    MinLenStalk = 0.9*12/NumberLeaves               // um
    setStalks(MaxDimStalk, MinDimStalk, MaxLenStalk, MinLenStalk, nanoDistrLoaded, DensityGluTransporters)
    OnlySingleGluSimulations = 1 // parameter for Glu and Potassium single  voltage clamp mechanism
    dt = 1
    steps_per_ms = 1                // ms   
    tstop = 10000                   // ms
    v_init = -85                    // mV
    finitialize(v_init)
}

// Opens the main program window.
proc runMain() {
    initCell()
    initParamsMain()
    showRunPanel()
    showMainUi()
}

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