Activity-dependent extracellular potassium changes in unmyelinated versus myelinated areas in olfactory regions of the isolated female guinea-pig brain.

Autor: Uva L; Epilepsy Unit, Fondazione IRCCS Istituto Neurologico Carlo Besta, via Celoria 11/via Amadeo 42, Milano, Italy.. Electronic address: Laura.Uva@istituto-besta.it., Bruno G; Epilepsy Unit, Fondazione IRCCS Istituto Neurologico Carlo Besta, via Celoria 11/via Amadeo 42, Milano, Italy.; Dipartimento di Biologia e Biotecnologia, via Forlanini, 6, Università di Pavia, 27100, Pavia, Italy.. Electronic address: gaia.bruno01@universitadipavia.it., de Curtis M; Epilepsy Unit, Fondazione IRCCS Istituto Neurologico Carlo Besta, via Celoria 11/via Amadeo 42, Milano, Italy.. Electronic address: marco.decurtis@istituto-besta.it.
Jazyk: angličtina
Zdroj: Experimental neurology [Exp Neurol] 2024 Sep; Vol. 379, pp. 114884. Date of Electronic Publication: 2024 Jul 09.
DOI: 10.1016/j.expneurol.2024.114884
Abstrakt: The potassium released in the extracellular space during neuronal activity is rapidly removed by glia and neurons to maintain tissue homeostasis. Oligodendrocyte-derived myelin axonal coating contributes to potassium buffering and is therefore crucial to control brain excitability. We studied activity-dependent extracellular potassium ([K + ] o ) changes in the piriform cortex (PC), a region that features highly segregated bundles of myelinated and unmyelinated fibers. Four-aminopyridine (4AP; 50 μM) treatment or patterned high-frequency stimulations (hfST) were utilized to generate [K + ] o changes measured with potassium-sensitive electrodes in the myelinated lateral olfactory tract (LOT), in the unmyelinated PC layer I and in the myelinated deep PC layers in the ex vivo isolated guinea-pig brain. Seizure-like events induced by 4AP are initiated by the abrupt [K + ] o rise in the layer I formed by unmyelinated fibers (Uva et al., 2017). Larger [K + ] o shifts occurred in unmyelinated layers compared to the myelinated LOT. LOT hfST that mimicks pre-seizure discharges also generated higher [K + ] o changes in unmyelinated PC layer I than in LOT and deep PC layers. The treatment with the Kir4.1 potassium channel blocker BaCl 2 (100 μM) enhanced the [K + ] o changes generated by hfST in myelinated structures. Our data show that activity-dependent [K + ] o changes are intrinsically different in myelinated vs unmyelinated cortical regions. The larger [K + ] o shifts generated in unmyelinated structures may represent a vehicle for seizure generation.
Competing Interests: Declaration of competing interest None.
(Copyright © 2024 Elsevier Inc. All rights reserved.)
Databáze: MEDLINE
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