Abstracts

Rationale: Dravet syndrome is a debilitating and catastrophic childhood epilepsy. Available antiseizure drugs fail to effectively treat this disease. The continued pharmaco-refractory nature of this disorder suggests novel approaches to drug-screening are needed. Our long-term goal is to use zebrafish and mice models of Dravet to uncover new drugs for this patient population. Using zebrafish, we developed a metabolism-based drug screening platform that assays for decreases in metabolic hyperexcitability as an unbiased approach to uncover antiseizure drugs with new mechanisms of action. Here we compared efficacies of 25 antiseizure drugs across two zebrafish models of Dravet syndrome, to gain insight into the similarities and differences between Dravet models with distinct genetic underpinnings. Methods: We used CRIPSR/cas9 to introduce mutations into the zebrafish ortholog of human SCN1A (e.g., scn1lab) and GABRA1 (e.g., gabra1) epilepsy-associated genes to create both Dravet models.  Extensive metabolic profiles of both scn1lab and gabra1 mutant zebrafish were analyzed withXF24e Seahorse Bioanalyzer. We conducted a shelf screen of 25 known antiseizure drugs in both models to test their ability to restore altered metabolic functions.  Results: The scn1lab and gabra1 mutant zebrafish exhibited distinctly opposite bioenergetics phenotypes for oxidative phosphorylation and glycolysis, including altered basal respiration, mitochondrially-mediated respiration, and ATP-linked respiration. Interestingly however, similar numbers (8-10) of antiseizure drugs were effective in both models. There was only 25-30% drug overlap between both models. The fewer number of compounds efficacious in the Dravet syndrome models is consistent with the pharmaco-refractory nature of this disease. Conclusions: Our metabolic approach to drug screening represents a new direction that can be used to identify novel therapeutics for monogenic intractable epilepsy. Funding: This work was funded by Brain Canada Platform Support Grant and Alberta Children’s Hospital Foundation.