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

IF 4.6 2区医学 Q1 NEUROSCIENCES

Experimental Neurology Pub Date : 2024-07-09 DOI:10.1016/j.expneurol.2024.114884

Laura Uva , Gaia Bruno , Marco de Curtis

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Abstract

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 BaCl₂ (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.

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离体雌性豚鼠大脑嗅觉区域中无髓鞘区与有髓鞘区的细胞外钾变化与活动有关。

神经元活动时释放到细胞外空间的钾会被神经胶质细胞和神经元迅速清除，以维持组织的平衡。源于少突胶质细胞的髓鞘轴突包膜有助于钾缓冲，因此对控制大脑兴奋性至关重要。我们研究了梨状皮层（PC）活动依赖性细胞外钾（[K+]o）变化，该区域具有高度分离的有髓鞘和无髓鞘纤维束。利用四氨基吡啶（4AP；50 μM）处理或模式化高频刺激（hfST），在髓鞘外侧嗅束（LOT）、未髓鞘化的PC I层和髓鞘化的PC深层用钾敏电极测量[K+]o的变化。4AP 诱导的癫痫样事件是由无髓鞘纤维形成的 I 层中[K+]o 的突然升高引发的（Uva 等人，2017 年）。与有髓鞘的 LOT 相比，无髓鞘层发生的[K+]o 变化更大。模拟癫痫发作前放电的 LOT hfST 也会在无髓鞘 PC I 层产生比 LOT 和 PC 深层更高的[K+]o 变化。Kir4.1 钾通道阻断剂 BaCl2（100 μM）可增强 hfST 在有髓鞘结构中产生的[K+]o 变化。我们的数据表明，在有髓鞘和无髓鞘皮质区域，活动依赖性[K+]o变化本质上是不同的。在无髓鞘结构中产生的较大[K+]o变化可能是癫痫发作的载体。

本文章由计算机程序翻译，如有差异，请以英文原文为准。

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来源期刊

Experimental Neurology 医学-神经科学

CiteScore

10.10

自引率

3.80%

发文量

258

审稿时长

42 days

期刊介绍： Experimental Neurology, a Journal of Neuroscience Research, publishes original research in neuroscience with a particular emphasis on novel findings in neural development, regeneration, plasticity and transplantation. The journal has focused on research concerning basic mechanisms underlying neurological disorders.

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