title: Pharmacological characterization of an antisense knockdown zebrafish model of Dravet syndrome: inhibition of epileptic seizures by the serotonin agonist fenfluramine.
abstract: Dravet syndrome (DS) is one of the most pharmacoresistant and devastating forms of childhood epilepsy syndromes. Distinct de novo mutations in the SCN1A gene are responsible for over 80% of DS cases. While DS is largely resistant to treatment with existing anti-epileptic drugs, promising results have been obtained in clinical trials with human patients treated with the serotonin agonist fenfluramine as an add-on therapeutic. We developed a zebrafish model of DS using morpholino antisense oligomers (MOs) targeting scn1Lab, the zebrafish ortholog of SCN1A. Zebrafish larvae with an antisense knockdown of scn1Lab (scn1Lab morphants) were characterized by automated behavioral tracking and high-resolution video imaging, in addition to measuring brain activity through local field potential recordings. Our findings reveal that scn1Lab morphants display hyperactivity, convulsive seizure-like behavior, loss of posture, repetitive jerking and a myoclonic seizure-like pattern. The occurrence of spontaneous seizures was confirmed by local field potential recordings of the forebrain, measuring epileptiform discharges. Furthermore, we show that these larvae are remarkably sensitive to hyperthermia, similar to what has been described for mouse models of DS, as well as for human DS patients. Pharmacological evaluation revealed that sodium valproate and fenfluramine significantly reduce epileptiform discharges in scn1Lab morphants. Our findings for this zebrafish model of DS are in accordance with clinical data for human DS patients. To our knowledge, this is the first study demonstrating effective seizure inhibition of fenfluramine in an animal model of Dravet syndrome. Moreover, these results provide a basis for identifying novel analogs with improved activity and significantly milder or no side effects.
authors.affiliation: Laboratory for Molecular Biodiscovery, Department of Pharmaceutical and Pharmacological Sciences, University of Leuven, Leuven, Belgium.
authors.forename: Yifan
authors.initials: Y
authors.lastname: Zhang
authors.affiliation: Laboratory for Molecular Biodiscovery, Department of Pharmaceutical and Pharmacological Sciences, University of Leuven, Leuven, Belgium.
authors.forename: Angéla
authors.initials: A
authors.lastname: Kecskés
authors.affiliation: Laboratory for Molecular Biodiscovery, Department of Pharmaceutical and Pharmacological Sciences, University of Leuven, Leuven, Belgium.
authors.forename: Daniëlle
authors.initials: D
authors.lastname: Copmans
authors.affiliation: Luxembourg Center for Systems Biomedicine, University of Luxembourg, Esch-sur-Alzette, Luxembourg.
authors.forename: Mélanie
authors.initials: M
authors.lastname: Langlois
authors.affiliation: Laboratory for Molecular Biodiscovery, Department of Pharmaceutical and Pharmacological Sciences, University of Leuven, Leuven, Belgium; Luxembourg Center for Systems Biomedicine, University of Luxembourg, Esch-sur-Alzette, Luxembourg.
authors.forename: Alexander D
authors.initials: AD
authors.lastname: Crawford
authors.affiliation: Department of Neurology-Child Neurology, University Hospital Antwerp & University of Antwerp, Antwerp, Belgium.
authors.forename: Berten
authors.initials: B
authors.lastname: Ceulemans
authors.affiliation: Department of Paediatric Neurology, University Hospitals Leuven, Leuven, Belgium.
authors.forename: Lieven
authors.initials: L
authors.lastname: Lagae
authors.affiliation: Laboratory for Molecular Biodiscovery, Department of Pharmaceutical and Pharmacological Sciences, University of Leuven, Leuven, Belgium.
authors.forename: Peter A M
authors.initials: PA
authors.lastname: de Witte
authors.affiliation: Laboratory for Molecular Biodiscovery, Department of Pharmaceutical and Pharmacological Sciences, University of Leuven, Leuven, Belgium.
authors.forename: Camila V
authors.initials: CV
authors.lastname: Esguerra
mesh_terms: D000818:Animals; D000927:Anticonvulsants / Q000008:administration & dosage / Q000627:therapeutic use; D004195:Disease Models, Animal; D004831:Epilepsies, Myoclonic / Q000188:drug therapy* / Q000235:genetics* / Q000473:pathology; D005277:Fenfluramine / Q000008:administration & dosage* / Q000627:therapeutic use; D055785:Gene Knockdown Techniques; D006801:Humans; D060172:Morpholinos / Q000378:metabolism; D062550:NAV1.1 Voltage-Gated Sodium Channel / Q000235:genetics* / Q000378:metabolism; D016376:Oligonucleotides, Antisense / Q000378:metabolism; D017367:Selective Serotonin Reuptake Inhibitors / Q000008:administration & dosage* / Q000627:therapeutic use; D014635:Valproic Acid / Q000008:administration & dosage / Q000627:therapeutic use; D015027:Zebrafish; D029961:Zebrafish Proteins / Q000235:genetics* / Q000378:metabolism
chemical_list: D000927:Anticonvulsants; D005277:Fenfluramine; D060172:Morpholinos; D062550:NAV1.1 Voltage-Gated Sodium Channel; D016376:Oligonucleotides, Antisense; D017367:Selective Serotonin Reuptake Inhibitors; D014635:Valproic Acid; D029961:Zebrafish Proteins