Heylen Lise, Pham Duc-Hung, De Meulemeester Ann-Sofie, Samarut Éric, Skiba Adrianna, Copmans Daniëlle, Kazwiny Youcef, Vanden Berghe Pieter, de Witte Peter A M, Siekierska Aleksandra
Laboratory for Molecular Biodiscovery, KU Leuven, Leuven, Belgium.
Department of Neurosciences, Research Center of the University of Montreal Hospital Center, University of Montreal, Montreal, QC, Canada.
Front Mol Neurosci. 2021 Oct 14;14:753936. doi: 10.3389/fnmol.2021.753936. eCollection 2021.
Epilepsy is a common disorder of the brain characterized by spontaneous recurrent seizures, which develop gradually during a process called epileptogenesis. The mechanistic processes underlying the changes of brain tissue and networks toward increased seizure susceptibility are not fully understood. In rodents, injection of kainic acid (KA) ultimately leads to the development of spontaneous epileptic seizures, reflecting similar neuropathological characteristics as seen in patients with temporal lobe epilepsy (TLE). Although this model has significantly contributed to increased knowledge of epileptogenesis, it is technically demanding, costly to operate and hence not suitable for high-throughput screening of anti-epileptic drugs (AEDs). Zebrafish, a vertebrate with complementary advantages to rodents, is an established animal model for epilepsy research. Here, we generated a novel KA-induced epilepsy model in zebrafish larvae that we functionally and pharmacologically validated. KA was administered by pericardial injection at an early zebrafish larval stage. The epileptic phenotype induced was examined by quantification of seizure-like behavior using automated video recording, and of epileptiform brain activity measured via local field potential (LFP) recordings. We also assessed GFP-labeled GABAergic and RFP-labeled glutamatergic neurons in double transgenic KA-injected zebrafish larvae, and examined the GABA and glutamate levels in the larval heads by liquid chromatography with tandem mass spectrometry detection (LC-MS/MS). Finally, KA-injected larvae were exposed to five commonly used AEDs by immersion for pharmacological characterization of the model. Shortly after injection, KA induced a massive damage and inflammation in the zebrafish brain and seizure-like locomotor behavior. An abnormal reorganization of brain circuits was observed, a decrease in both GABAergic and glutamatergic neuronal population and their associated neurotransmitters. Importantly, these changes were accompanied by spontaneous and continuous epileptiform brain discharges starting after a short latency period, as seen in KA rodent models and reminiscent of human pathology. Three out of five AEDs tested rescued LFP abnormalities but did not affect the seizure-like behavior. Taken together, for the first time we describe a chemically-induced larval zebrafish epilepsy model offering unique insights into studying epileptogenic processes and suitable for high-throughput AED screening purposes and rapid genetic investigations.
癫痫是一种常见的脑部疾病，其特征为自发性反复发作的癫痫发作，这些发作在一个称为癫痫发生的过程中逐渐发展。脑组织和神经网络向癫痫易感性增加转变的机制过程尚未完全明了。在啮齿动物中，注射 kainic 酸（KA）最终会导致自发性癫痫发作的发生，反映出与颞叶癫痫（TLE）患者相似的神经病理学特征。尽管该模型对增加癫痫发生的认识有显著贡献，但它技术要求高、操作成本高，因此不适合用于抗癫痫药物（AEDs）的高通量筛选。斑马鱼作为一种与啮齿动物具有互补优势的脊椎动物，是一种成熟的癫痫研究动物模型。在此，我们在斑马鱼幼体中建立了一种新的 KA 诱导癫痫模型，并对其进行了功能和药理学验证。在斑马鱼幼体早期通过心包注射给予 KA。通过使用自动视频记录对癫痫样行为进行量化，以及通过局部场电位（LFP）记录测量癫痫样脑活动，来检查诱导的癫痫表型。我们还评估了双转基因 KA 注射斑马鱼幼体中 GFP 标记的 GABA 能神经元和 RFP 标记的谷氨酸能神经元，并通过液相色谱串联质谱检测（LC-MS/MS）检查幼体头部的 GABA 和谷氨酸水平。最后，通过浸泡将 KA 注射的幼体暴露于五种常用的 AEDs 中，以对该模型进行药理学特征分析。注射后不久，KA 在斑马鱼脑中引起大量损伤和炎症以及癫痫样运动行为。观察到脑回路的异常重组，GABA 能和谷氨酸能神经元群体及其相关神经递质减少。重要的是，这些变化伴随着在短暂潜伏期后开始的自发性和持续性癫痫样脑放电，这在 KA 啮齿动物模型中可见，并且让人联想到人类病理学情况。测试的五种 AEDs 中有三种挽救了 LFP 异常，但不影响癫痫样行为。综上所述，我们首次描述了一种化学诱导的斑马鱼幼体癫痫模型，该模型为研究癫痫发生过程提供了独特的见解，适用于高通量 AED 筛选目的和快速基因研究。
