Previous studies demonstrated that pentylenetetrazole (PTZ), a GABA type A receptor (GABAAR) antagonist, elicits seizure-like phenotypes in larval zebrafish (Danio rerio). Here, we determined whether the GABAAR antagonists, tetramethylenedisulfotetramine (TETS) and picrotoxin (PTX), both listed as credible chemical threat agents, similarly trigger seizures in zebrafish larvae. Larvae of three, routinely used laboratory zebrafish lines, Tropical 5D, NHGRI and Tupfel long fin, were exposed to varying concentrations of PTZ (used as a positive control), PTX or TETS for 20 min at 5 days post fertilization (dpf). Acute exposure to PTZ, PTX or TETS triggered seizure behavior in the absence of morbidity or mortality. While the concentration-effect relationship for seizure behavior was similar across zebrafish lines for each GABAAR antagonist, significantly less TETS was required to trigger seizures relative to PTX or PTZ. Recordings of extracellular field potentials in the optic tectum of 5 dpf Tropical 5D zebrafish confirmed that all three GABAAR antagonists elicited extracellular spiking patterns consistent with seizure activity, although the pattern varied between chemicals. Post-exposure treatment with the GABAAR positive allosteric modulators (PAMs), diazepam, midazolam or allopregnanolone, attenuated seizure behavior and activity but did not completely normalize electrical field recordings in the optic tectum. These data are consistent with observations of seizure responses in mammalian models exposed to these same GABAAR antagonists and PAMs, further validating larval zebrafish as a higher throughput-screening platform for antiseizure therapeutics, and demonstrating its appropriateness for identifying improved countermeasures for TETS and other convulsant chemical threat agents that trigger seizures via GABAAR antagonism.

中文翻译：

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幼虫斑马鱼对GABA A型受体拮抗剂的致癫痫活性的敏感性。

先前的研究表明，戊巴四唑（PTZ）是一种GABA A型受体（GABAAR）拮抗剂，在幼虫斑马鱼（Danio rerio）中会引起癫痫样表型。在这里，我们确定了被列为可靠化学威胁剂的GABAAR拮抗剂四亚甲基二磺基四胺（TETS）和微毒素（PTX）是否同样触发斑马鱼幼虫的癫痫发作。受精（dpf）后5天，将三个常规使用的实验室斑马鱼品系（热带5D，NHGRI和Tupfel长鳍）的幼虫暴露于不同浓度的PTZ（用作阳性对照），PTX或TETS中20分钟。在没有发病或死亡的情况下，急性暴露于PTZ，PTX或TEDS会引发癫痫发作。尽管每种GABAAR拮抗剂在斑马鱼品系中癫痫行为的浓度-效应关系相似，相对于PTX或PTZ，触发癫痫发作所需的TETS明显更少。在5 dpf热带5D斑马鱼视神经皮层中记录的细胞外场电势证实，所有三种GABAAR拮抗剂均引起与癫痫发作活动一致的细胞外突刺模式，尽管该模式在化学物质之间有所不同。用GABAAR阳性变构调节剂（PAMs），地西epa，咪达唑仑或allopregnanolone进行暴露后治疗，可减弱癫痫发作的行为和活动，但并未完全使视皮层中的电场记录正常化。这些数据与暴露于这些相同GABAAR拮抗剂和PAM的哺乳动物模型中癫痫发作反应的观察结果一致，进一步验证了幼虫斑马鱼作为抗癫痫治疗药的更高通量筛选平台，