Clemizole and trazodone are effective antiseizure treatments in a zebrafish model of STXBP1 disorder

Abstract

CRISPR‐Cas9–generated zebrafish carrying a 12 base‐pair deletion in stxbpb1b, a paralog sharing 79% amino acid sequence identity with human, exhibit spontaneous electrographic seizures during larval stages of development. Zebrafish stxbp1b mutants provide an efficient preclinical platform to test antiseizure therapeutics. The present study was designed to test antiseizure medications approved for clinical use and two recently identified repurposed drugs with antiseizure activity. Larval homozygous stxbp1b zebrafish (4 days postfertilization (dpf)) were agarose‐embedded and monitored for electrographic seizure activity using a local field recording electrode placed in midbrain. Frequency of ictal‐like events was evaluated at baseline and following 45 min of continuous drug exposure (1 mM, bath application). Analysis was performed on coded files by an experimenter blinded to drug treatment and genotype. Phenytoin (PHT), valproate (VPA), ethosuximide (ESX), levetiracetam (LEV), and diazepam (DZP) had no effect on the ictal‐like event frequency in stxbp1b mutant zebrafish. Clemizole and trazodone decreased ictal‐like event frequency in stxbp1b mutant zebrafish by 80% and 83%, respectively. These results suggest that repurposed drugs with serotonin receptor–binding affinities could be effective antiseizure treatments. Clemizole and trazodone were previously identified in a larval zebrafish model for Dravet syndrome. Based primarily on these preclinical zebrafish studies, compassionate‐use and double‐blind clinical trials with both drugs have progressed. The present study extends this approach to a preclinical zebrafish model representing STXBP1 (syntaxin‐binding protein 1)‐related disorders and suggests that future clinical studies may be warranted.

Establishment of innovative ZebVortrack behavioral analysis system for quantitative epileptic seizure assessment in larval zebrafish

“…In this experiment, the ZebVortrack system was used to evaluate a variety of antiseizure drugs, and the results showed that these antiseizure drugs could reduce the activity frequency of larval zebra sh and suppress the seizure-like behavior induced by PTZ, which is in accordance with previous reports [34][35][36][37] .…”

STXBP1-Related Disorders: Clinical Presentation, Molecular Function, Treatment, and Future Directions

“…Another treatment option that has been considered is to trial medications that interact with serotonin receptors. The screening of various antiseizure medications in a zebrafish model of STXBP1-related disorders identified Clemizole and Trazodone as medications that decreased ictal events [64]. These findings suggest that medications with serotoninreceptor-binding affinities could be an effective antiseizure medication option, although further research is needed.…”

“…In recent years, a zebrafish animal model for STXBP1-related disorders has been developed [69,70]. Already these models have been used to screen antiseizure medications [64] and have been used to visualize in vivo network dynamics [59]. This may function to easily screen medications, as well as monitor changes in network dynamics.…”

Testing of putative antiseizure drugs in a preclinical Dravet syndrome zebrafish model

“…Recording chambers were placed on the stage of an upright microscope (Olympus BX-51W) and monitored continuously using a Zeiss Axiocam digital camera. Under visual guidance, gap-free LFP recordings (15 minute duration) were obtained from the optic tectum using a single-glass microelectrode (WPI glass #TW150 F-3) with approximately 1 µM tip diameter backfilled with 2 mM NaCl internal solution as described previously 29,[37][38][39][40] .…”