A Single Seizure Episode Leads to Rapid Functional Activation of KCC2 in the Neonatal Rat Hippocampus

Khirug, Stanislav; Ahmad, Faraz; Puskarjov, Martin; Afzalov, Ramil; Kaila, Kai; Blaesse, Peter

doi:10.1523/jneurosci.3154-10.2010

Cited by 89 publications

(101 citation statements)

References 43 publications

(69 reference statements)

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“…transporter proteins, including NKCC1 and KCC2 (Rivera et al, 2004;Jin et al, 2005;Dzhala et al, 2010;Khirug et al, 2010). However, we found that adenosine had no direct effect on steadystate E GABAA or the recovery of depolarizing GABA A R responses back to hyperpolarizing.…”

Section: Discussionmentioning

confidence: 61%

Adenosine Release during Seizures Attenuates GABA_AReceptor-Mediated Depolarization

Ilie¹,

Raimondo²,

Akerman³

2012

J. Neurosci.

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Seizure-induced release of the neuromodulator adenosine is a potent endogenous anticonvulsant mechanism, which limits the extension of seizures and mediates seizure arrest. For this reason several adenosine-based therapies for epilepsy are currently under development. However, it is not known how adenosine modulates GABAergic transmission in the context of seizure activity. This may be particularly relevant as strong activation of GABAergic inputs during epileptiform activity can switch GABA A receptor (GABA A R) signaling from inhibitory to excitatory, which is a process that plays a significant role in intractable epilepsies. We used gramicidin-perforated patchclamp recordings to investigate the role of seizure-induced adenosine release in the modulation of postsynaptic GABA A R signaling in pyramidal neurons of rat hippocampus. Consistent with previous reports, GABA A R responses during seizure activity transiently switched from hyperpolarizing to depolarizing and excitatory. We found that adenosine released during the seizure significantly attenuated the depolarizing GABA A R responses and also reduced the extent of the after-discharge phase of the seizure. These effects were mimicked by exogenous adenosine administration and could not be explained by a change in chloride homeostasis mechanisms that set the reversal potential for GABA A Rs, or by a change in the conductance of GABA A Rs. Rather, A 1 R-dependent activation of potassium channels increased the cell's membrane conductance and thus had a shunting effect on GABA A R currents. As depolarizing GABA A R signaling has been implicated in seizure initiation and progression, the adenosine-induced attenuation of depolarizing GABA A R signaling may represent an important mechanism by which adenosine can limit seizure activity.

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Section: Discussionmentioning

confidence: 61%

Adenosine Release during Seizures Attenuates GABA_AReceptor-Mediated Depolarization

Ilie¹,

Raimondo²,

Akerman³

2012

J. Neurosci.

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“…Imposing a defined somatic Cl Ϫ load via the patch pipette enables assessment of the efficacy of Cl Ϫ extrusion. As shown previously (Khirug et al, 2005(Khirug et al, , 2008(Khirug et al, , 2010Blaesse et al, 2006;Li et al, 2007;Gauvain et al, 2011), functional expression of KCC2 results in a somatodendritic gradient of [Cl Ϫ ] i , which can be measured as a gradient in E GABA between the somatic and dendritic compartments (⌬E GABA ). Notably, control levels of ⌬E GABA remained unchanged for the experimental duration of 0 -4 h (0 -2 h: Ϫ6.05 Ϯ 0.31 mV/50 m; n ϭ 12 cells; 3-4 h: Ϫ6.28 Ϯ 0.28 mV/50 m; n ϭ 14 cells).…”

Section: Total Block Of Protein Synthesis Does Not Affect Kcc2 Proteimentioning

confidence: 63%

“…In some experiments, calpain-2 was preincubated with 100 M MDL-28170 for 5 min. (Khirug et al, 2010;Ahmad et al, 2011) was used to analyze the surface expression of KCC2. Briefly, transverse hippocampal slices were treated with cod trypsin (Zymetech), a protease that retains its activity at low temperatures while trafficking of membrane proteins is blocked.…”

Section: Methodsmentioning

confidence: 99%

“…Cells with stable access resistance between 10 and 20 M⍀, and resting membrane potential below Ϫ55 mV were accepted for analysis. The efficacy of KCC2-mediated Cl Ϫ extrusion was quantified on the basis of ⌬E GABA , which was measured as the difference between the reversal potential of GABA A -mediated currents (E GABA ) at the soma and at 50 m away along the apical dendrite (Khirug et al, 2010). Membrane potential was held at Ϫ50 mV to reduce the driving force for outward leak Cl Ϫ conductance and to minimize its contribution to the measured Cl Ϫ extrusion.…”

Section: Methodsmentioning

confidence: 99%

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Activity-Dependent Cleavage of the K-Cl Cotransporter KCC2 Mediated by Calcium-Activated Protease Calpain

et al. 2012

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The K-Cl cotransporter KCC2 plays a crucial role in neuronal chloride regulation. In mature central neurons, KCC2 is responsible for the low intracellular Cl Ϫ concentration ([Cl Ϫ ] i ) that forms the basis for hyperpolarizing GABA A receptor-mediated responses. Fast changes in KCC2 function and expression have been observed under various physiological and pathophysiological conditions. Here, we show that the application of protein synthesis inhibitors cycloheximide and emetine to acute rat hippocampal slices have no effect on total KCC2 protein level and K-Cl cotransporter function. Furthermore, blocking constitutive lysosomal degradation with leupeptin did not induce significant changes in KCC2 protein levels. These findings indicate a low basal turnover rate of the total KCC2 protein pool. In the presence of the glutamate receptor agonist NMDA, the total KCC2 protein level decreased to about 30% within 4 h, and this effect was blocked by calpeptin and MDL-28170, inhibitors of the calcium-activated protease calpain. Interictal-like activity induced by incubation of hippocampal slices in an Mg 2ϩ -free solution led to a fast reduction in KCC2-mediated Cl Ϫ transport efficacy in CA1 pyramidal neurons, which was paralleled by a decrease in both total and plasmalemmal KCC2 protein. These effects were blocked by the calpain inhibitor MDL-28170. Taken together, these findings show that calpain activation leads to cleavage of KCC2, thereby modulating GABAergic signaling.

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“…These results suggest that nerve injury reduces KCC2 protein levels and synaptic inhibition in the spinal cord through activation of NMDARs and subsequent Ca 2ϩ influx. Nerve Injury Induces Proteolysis of KCC2 at the C Terminus through NMDAR Activation-The KCC2 protein is present in both the plasma membrane and cytoplasmic fractions (12,34). To determine whether nerve injury alters the subcellular distribution of KCC2 in the spinal cord, we analyzed the protein level of KCC2 in the plasma membrane and cytosolic fractions in the dorsal spinal cords of SNL rats.…”

Section: Nerve Injury Switches Glycine-mediated Synaptic Inhibition Tmentioning

confidence: 99%

N-Methyl-d-aspartate Receptor- and Calpain-mediated Proteolytic Cleavage of K+-Cl− Cotransporter-2 Impairs Spinal Chloride Homeostasis in Neuropathic Pain

Zhou

Chen

Byun

et al. 2012

Journal of Biological Chemistry

125

159

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A Single Seizure Episode Leads to Rapid Functional Activation of KCC2 in the Neonatal Rat Hippocampus

Abstract: Functional expression of the K-Cl cotransporter KCC2 in developing central neurons is crucial for the maturation of Cl

Cited by 89 publications

References 43 publications

Adenosine Release during Seizures Attenuates GABA_AReceptor-Mediated Depolarization

Adenosine Release during Seizures Attenuates GABA_AReceptor-Mediated Depolarization

Activity-Dependent Cleavage of the K-Cl Cotransporter KCC2 Mediated by Calcium-Activated Protease Calpain

N-Methyl-d-aspartate Receptor- and Calpain-mediated Proteolytic Cleavage of K+-Cl− Cotransporter-2 Impairs Spinal Chloride Homeostasis in Neuropathic Pain

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A Single Seizure Episode Leads to Rapid Functional Activation of KCC2 in the Neonatal Rat Hippocampus

Abstract: Functional expression of the K-Cl cotransporter KCC2 in developing central neurons is crucial for the maturation of Cl

Cited by 89 publications

References 43 publications

Adenosine Release during Seizures Attenuates GABAAReceptor-Mediated Depolarization

Adenosine Release during Seizures Attenuates GABAAReceptor-Mediated Depolarization

Activity-Dependent Cleavage of the K-Cl Cotransporter KCC2 Mediated by Calcium-Activated Protease Calpain

N-Methyl-d-aspartate Receptor- and Calpain-mediated Proteolytic Cleavage of K+-Cl− Cotransporter-2 Impairs Spinal Chloride Homeostasis in Neuropathic Pain

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Adenosine Release during Seizures Attenuates GABA_AReceptor-Mediated Depolarization

Adenosine Release during Seizures Attenuates GABA_AReceptor-Mediated Depolarization