Status epilepticus alters dentate basket cell tonic inhibition (Yu J et al 2013)

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Accession:155602
Status epilepticus (SE) leads to changes in dentate inhibitory neuronal networks and alters synaptic and tonic inhibition in granule cells. Recently, we identified that one week after pilocarpine-induced status epilepticus, dentate fast-spiking basket cells (FS-BCs), which underlie fast perisomatic inhibition, show two distinct changes in inhibition: (1) enhanced tonic currents (IGABA) and (2)depolarizing shift in GABA reversal (EGABA) following SE. These two changes can have opposing effects on neuronal inhibition with increases in tonic GABA conductance (gGABA) reducing excitability when the GABA currents are shunting (or hyperpolarizing) and potentially enhancing excitability when GABA currents are depolarizing. The following model is used to examine the post-SE changes in tonic GABA conductance, together with the depolarized GABA reversal potential modify FS-BC excitability and dentate network activity.
Reference:
1 . Yu J, Proddutur A, Elgammal FS, Ito T, Santhakumar V (2013) Status epilepticus enhances tonic GABA currents and depolarizes GABA reversal potential in dentate fast-spiking basket cells. J Neurophysiol 109:1746-63 [PubMed]
Model Information (Click on a link to find other models with that property)
Model Type: Realistic Network;
Brain Region(s)/Organism:
Cell Type(s): Dentate gyrus basket cell;
Channel(s):
Gap Junctions:
Receptor(s): GabaA;
Gene(s):
Transmitter(s): Gaba;
Simulation Environment: NEURON;
Model Concept(s): Epilepsy;
Implementer(s):
Search NeuronDB for information about:  GabaA; Gaba;
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YuEtAl2013
ReadMe.html
bgka.mod *
CaBK.mod *
ccanl.mod *
gap.mod
Gfluct2.mod *
gskch.mod *
hyperde3.mod *
ichan2.mod *
LcaMig.mod *
markov.mod *
nca.mod *
tca.mod *
tonic.mod *
fixed rseed Control -74 spill_ tonic 10uS with mossy kill.hoc
fixed rseed Pilo -54 spill_ tonic 10uS with mossy kill.hoc
mosinit.hoc
screenshot1.png
                            
COMMENT
	calcium accumulation into a volume of area*depth next to the
	membrane with a decay (time constant tau) to resting level
	given by the global calcium variable cai0_ca_ion
ENDCOMMENT

NEURON {
	SUFFIX ccanl
USEION nca READ ncai, inca, enca WRITE enca, ncai VALENCE 2
USEION lca READ lcai, ilca, elca WRITE elca, lcai VALENCE 2
USEION tca READ tcai, itca, etca WRITE etca, tcai VALENCE 2
RANGE caiinf, catau, cai, ncai, lcai,tcai, eca, elca, enca, etca
}

UNITS {
        (mV) = (millivolt)
	(molar) = (1/liter)
	(mM) = (milli/liter)
	(mA) = (milliamp)
	FARADAY = 96520 (coul)
	R = 8.3134	(joule/degC)
}

INDEPENDENT {t FROM 0 TO 100 WITH 100 (ms)}

PARAMETER {
        celsius = 6.3 (degC)
	depth = 200 (nm)	: assume volume = area*depth
	catau = 9 (ms)
	caiinf = 50.e-6 (mM)	: takes precedence over cai0_ca_ion
			: Do not forget to initialize in hoc if different
			: from this default.
	cao = 2 (mM)
	ica (mA/cm2)
	inca (mA/cm2)
	ilca (mA/cm2)
	itca (mA/cm2)
	cai= 50.e-6 (mM)
}

ASSIGNED {
	enca (mV)
	elca (mV)
	etca (mV)
	eca (mV)
}

STATE {
	ncai (mM)
	lcai (mM)
	tcai (mM)
}

INITIAL {
	VERBATIM
	ncai = _ion_ncai;
	lcai = _ion_lcai;
	tcai = _ion_tcai; 
	ENDVERBATIM
	ncai=caiinf/3
	lcai=caiinf/3
	tcai=caiinf/3
	cai = caiinf	
	eca = ktf() * log(cao/caiinf)	
	enca = eca
	elca = eca
	etca = eca
}


BREAKPOINT {
	SOLVE integrate METHOD derivimplicit
	cai = ncai+lcai+tcai	
	eca = ktf() * log(cao/cai)	
	enca = eca
	elca = eca
	etca = eca
}

DERIVATIVE integrate {
ncai' = -(inca)/depth/FARADAY * (1e7) + (caiinf/3 - ncai)/catau
lcai' = -(ilca)/depth/FARADAY * (1e7) + (caiinf/3 - lcai)/catau
tcai' = -(itca)/depth/FARADAY * (1e7) + (caiinf/3 - tcai)/catau
}

FUNCTION ktf() (mV) {
	ktf = (1000)*R*(celsius +273.15)/(2*FARADAY)
} 

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