title: Altered Glycolysis and Mitochondrial Respiration in a Zebrafish Model of Dravet Syndrome.
abstract: Altered metabolism is an important feature of many epileptic syndromes but has not been reported in Dravet syndrome (DS), a catastrophic childhood epilepsy associated with mutations in a voltage-activated sodium channel, Nav1.1 (SCN1A). To address this, we developed novel methodology to assess real-time changes in bioenergetics in zebrafish larvae between 4 and 6 d postfertilization (dpf). Baseline and 4-aminopyridine (4-AP) stimulated glycolytic flux and mitochondrial respiration were simultaneously assessed using a Seahorse Biosciences extracellular flux analyzer. Scn1Lab mutant zebrafish showed a decrease in baseline glycolytic rate and oxygen consumption rate (OCR) compared to controls. A ketogenic diet formulation rescued mutant zebrafish metabolism to control levels. Increasing neuronal excitability with 4-AP resulted in an immediate increase in glycolytic rates in wild-type zebrafish, whereas mitochondrial OCR increased slightly and quickly recovered to baseline values. In contrast, scn1Lab mutant zebrafish showed a significantly slower and exaggerated increase of both glycolytic rates and OCR after 4-AP. The underlying mechanism of decreased baseline OCR in scn1Lab mutants was not because of altered mitochondrial DNA content or dysfunction of enzymes in the electron transport chain or tricarboxylic acid cycle. Examination of glucose metabolism using a PCR array identified five glycolytic genes that were downregulated in scn1Lab mutant zebrafish. Our findings in scn1Lab mutant zebrafish suggest that glucose and mitochondrial hypometabolism contribute to the pathophysiology of DS.
authors.affiliation: Department of Pharmaceutical Sciences, University of Colorado Anschutz Medical Campus , Aurora, Colorado 80045.
authors.forename: Maneesh G
authors.initials: MG
authors.lastname: Kumar
authors.affiliation: Department of Pharmaceutical Sciences, University of Colorado Anschutz Medical Campus , Aurora, Colorado 80045.
authors.forename: Shane
authors.initials: S
authors.lastname: Rowley
authors.affiliation: Department of Pharmaceutical Sciences, University of Colorado Anschutz Medical Campus , Aurora, Colorado 80045.
authors.forename: Ruth
authors.initials: R
authors.lastname: Fulton
authors.affiliation: Department of Neurological Surgery, University of California San Francisco , San Francisco, California 94143.
authors.forename: Matthew T
authors.initials: MT
authors.lastname: Dinday
authors.affiliation: Department of Neurological Surgery, University of California San Francisco , San Francisco, California 94143.
authors.forename: Scott C
authors.initials: SC
authors.lastname: Baraban
authors.affiliation: Department of Pharmaceutical Sciences, University of Colorado Anschutz Medical Campus , Aurora, Colorado 80045.
authors.forename: Manisha
authors.initials: M
authors.lastname: Patel
mesh_terms: D015761:4-Aminopyridine / Q000494:pharmacology; D000818:Animals; D030801:Animals, Genetically Modified; D002952:Citric Acid Cycle / Q000187:drug effects / Q000235:genetics; D055423:Diet, Ketogenic / Q000379:methods; D004195:Disease Models, Animal; D004831:Epilepsies, Myoclonic / Q000178:diet therapy / Q000235:genetics / Q000503:physiopathology*; D005786:Gene Expression Regulation / Q000187:drug effects / Q000235:genetics; D006019:Glycolysis / Q000187:drug effects / Q000235:genetics*; D006649:Histocompatibility Antigens / Q000378:metabolism; D007814:Larva; D008928:Mitochondria / Q000187:drug effects / Q000378:metabolism*; D009154:Mutation / Q000235:genetics; D062550:NAV1.1 Voltage-Gated Sodium Channel / Q000235:genetics / Q000378:metabolism; D010101:Oxygen Consumption / Q000187:drug effects / Q000235:genetics*; D026902:Potassium Channel Blockers / Q000494:pharmacology; D018709:Statistics, Nonparametric; D015027:Zebrafish
chemical_list: D006649:Histocompatibility Antigens; D062550:NAV1.1 Voltage-Gated Sodium Channel; D026902:Potassium Channel Blockers; D015761:4-Aminopyridine
keywords: Dravet syndrome; epilepsy; glycolysis; metabolism; mitochondrial respiration; zebrafish