Role of KCC2-dependent potassium efflux in 4-Aminopyridine-induced Epileptiform synchronization

NEUROBIOLOGY OF DISEASE

卷:109

Article

Gonzalez, Oscar C.^1,2  Shiri, Zahra³  Krishnan, Giri P.²  Myers, Timothy L.^6,7  Williams, Sylvain⁴  Avoli, Massimo^3,5  Bazhenov, Maxim^1,2 

[1] Univ Calif San Diego, Neurosci Grad Program, San Diego, CA 92103 USA

[2] Univ Calif San Diego, Dept Med, San Diego, CA 92103 USA

[3] McGill Univ, Montreal Neurol Inst, Montreal, PQ H4H 1R3, Canada

[4] McGill Univ, Douglas Mental Hlth Univ Inst, Montreal, PQ H4H 1R3, Canada

[5] McGill Univ, Dept Physiol, Montreal, PQ H4H 1R3, Canada

[6] Univ Calif Riverside, Neurosci Grad Program, Riverside, CA 92521 USA

[7] Univ Calif Riverside, Dept Cell Biol & Neurosci, Riverside, CA 92521 USA

关键词: KCC2 co-transporter;    4-aminopyridine;    Epileptic seizures;    Ion concentration dynamics;    Network models;   

DOI  :  10.1016/j.nbd.2017.10.011

来源: Elsevier

【 摘 要 】

A balance between excitation and inhibition is necessary to maintain stable brain network dynamics. Traditionally, seizure activity is believed to arise from the breakdown of this delicate balance in favor of excitation with loss of inhibition. Surprisingly, recent experimental evidence suggests that this conventional view may be limited, and that inhibition plays a prominent role in the development of epileptiform synchronization. Here, we explored the role of the KCC2 co-transporter in the onset of inhibitory network-induced seizures. Our experiments in acute mouse brain slices, of either sex, revealed that optogenetic stimulation of either parvalbumin- or somatostatin-expressing interneurons induced ictal discharges in rodent entorhinal cortex during 4-aminopyridine application. These data point to a preconvulsive role of GABA(A) receptor signaling that is independent of the inhibitory input location (ie., dendritic vs. somatic). We developed a biophysically realistic network model implementing dynamics of ion concentrations to explore the mechanisms leading to inhibitory network-induced seizures. In agreement with experimental results, we found that stimulation of the inhibitory interneurons induced seizure-like activity in a network with reduced potassium A-current. Our model predicts that interneuron stimulation triggered an increase of interneuron firing, which was accompanied by an increase in the intracellular chloride concentration and a subsequent KCC2-dependent gradual accumulation of the extracellular potassium promoting epileptiform ictal activity. When the KCC2 activity was reduced, stimulation of the interneurons was no longer able to induce ictal events. Overall, our study provides evidence for a pro-convulsive role of GABA(A) receptor signaling that depends on the involvement of the KCC2 co-transporter.

【 授权许可】

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