Faculty Opinions recommendation of New insights into the early mechanisms of epileptogenesis in a zebrafish model of Dravet syndrome.

Abstract Energy producing pathways are novel therapeutic targets for the treatment of neurodevelopmental disorders. Here, we focused on correcting metabolic defects in a catastrophic pediatric epilepsy, Dravet syndrome which is caused by mutations in sodium channel NaV1.1 gene, SCN1A. We utilized a translatable zebrafish model of Dravet syndrome (scn1lab) which exhibits key characteristics of Dravet syndrome patients and shows metabolic deficits accompanied by downregulation of gluconeogenesis genes, pck1 and pck2. Using a metabolism-based small library screen, we identified compounds that increased gluconeogenesis via upregulation of pck1 gene expression in scn1lab larvae. Treatment with PK11195, a pck1 activator and a translocator protein ligand, normalized dysregulated glucose levels, metabolic deficits, translocator protein expression and significantly decreased electrographic seizures in mutant larvae. Inhibition of pck1 in wild-type larvae mimicked metabolic and behavior defects observed in scn1lab mutants. Together, this suggests correcting dysregulated metabolic pathways can be therapeutic in neurodevelopmental disorders such as Dravet syndrome arising from ion channel dysfunction.

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Defective Excitatory/Inhibitory Synaptic Balance and Increased Neuron Apoptosis in a Zebrafish Model of Dravet Syndrome

Cells ◽

10.3390/cells8101199 ◽

2019 ◽

Vol 8 (10) ◽

pp. 1199 ◽

Cited By ~ 7

Author(s):

Alexandre Brenet ◽

Rahma Hassan-Abdi ◽

Julie Somkhit ◽

Constantin Yanicostas ◽

Nadia Soussi-Yanicostas

Keyword(s):

Local Field ◽

Local Field Potential ◽

Field Potential ◽

Dravet Syndrome ◽

Inhibitory Synapses ◽

Neuron Activity ◽

Loss Of Function ◽

Zebrafish Model ◽

Neuron Apoptosis

Dravet syndrome is a type of severe childhood epilepsy that responds poorly to current anti-epileptic drugs. In recent years, zebrafish disease models with Scn1Lab sodium channel deficiency have been generated to seek novel anti-epileptic drug candidates, some of which are currently undergoing clinical trials. However, the spectrum of neuronal deficits observed following Scn1Lab depletion in zebrafish larvae has not yet been fully explored. To fill this gap and gain a better understanding of the mechanisms underlying neuron hyperexcitation in Scn1Lab-depleted larvae, we analyzed neuron activity in vivo using combined local field potential recording and transient calcium uptake imaging, studied the distribution of excitatory and inhibitory synapses and neurons as well as investigated neuron apoptosis. We found that Scn1Lab-depleted larvae displayed recurrent epileptiform seizure events, associating massive synchronous calcium uptakes and ictal-like local field potential bursts. Scn1Lab-depletion also caused a dramatic shift in the neuronal and synaptic balance toward excitation and increased neuronal death. Our results thus provide in vivo evidence suggesting that Scn1Lab loss of function causes neuron hyperexcitation as the result of disturbed synaptic balance and increased neuronal apoptosis.

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in vivo Phenomic Screening System for Antiepileptic Drugs using Dravet Syndrome Zebrafish Model

Proceedings for Annual Meeting of The Japanese Pharmacological Society ◽

10.1254/jpssuppl.92.0_3-o-20 ◽

2019 ◽

Vol 92 (0) ◽

pp. 3-O-20

Author(s):

Mina Okamura ◽

Ikuko Mikami ◽

Junko Koiwa ◽

Yuka Takahashi ◽

Erina Kitahara ◽

...

Keyword(s):

Antiepileptic Drugs ◽

Dravet Syndrome ◽

Screening System ◽

Zebrafish Model

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Defective excitatory/inhibitory synaptic balance and increased neuron apoptosis in a zebrafish model of Dravet syndrome

10.1101/781393 ◽

2019 ◽

Author(s):

Alexandre Brenet ◽

Rahma Hassan-Abdi ◽

Julie Somkhit ◽

Constantin Yanicostas ◽

Nadia Soussi-Yanicostas

Keyword(s):

Local Field ◽

Local Field Potential ◽

Field Potential ◽

Dravet Syndrome ◽

Inhibitory Synapses ◽

Neuron Activity ◽

Loss Of Function ◽

Zebrafish Model ◽

Neuron Apoptosis

AbstractDravet syndrome is a type of severe childhood epilepsy that responds poorly to current anti-epileptic drugs. In recent years, zebrafish disease models with Scn1Lab sodium channel deficiency have been generated to seek novel anti-epileptic drug candidates, some of which are currently undergoing clinical trials. However, the spectrum of neuronal deficits observed following Scn1Lab depletion in zebrafish larvae has not yet been fully explored. To fill this gap and gain a better understanding of the mechanisms underlying neuron hyperexcitation in Scn1Lab-depleted larvae, we analyzed neuron activity in vivo using combined local field potential recording and transient calcium uptake imaging, studied the distribution of excitatory and inhibitory synapses and neurons as well as investigated neuron apoptosis. We found that Scn1Lab-depleted larvae displayed recurrent epileptiform seizure events, associating massive synchronous calcium uptakes and ictal-like local field potential bursts. Scn1Lab-depletion also caused a dramatic shift in the neuronal and synaptic balance toward excitation and increased neuronal death. Our results thus provide in vivo evidence suggesting that Scn1Lab loss of function causes neuron hyperexcitation as the result of disturbed synaptic balance and increased neuronal apoptosis.

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Phenotype-based screening of synthetic cannabinoids in a Dravet Syndrome zebrafish model

10.1101/815811 ◽

2019 ◽

Author(s):

Aliesha Griffin ◽

Mana Anvar ◽

Kyla Hamling ◽

Scott C. Baraban

Keyword(s):

Clinical Evidence ◽

Seizure Activity ◽

Synthetic Cannabinoids ◽

Field Potential ◽

Dravet Syndrome ◽

Zebrafish Model ◽

Spontaneous Seizures ◽

Increased Risk ◽

Potential Recording ◽

Field Potential Recording

Dravet syndrome (DS) is a catastrophic epilepsy of childhood, characterized by cognitive impairment, severe seizures and increased risk for sudden unexplained death in epilepsy (SUDEP). Although refractory to conventional antiepileptic drugs, emerging preclinical and clinical evidence suggests that modulation of the endocanniboid system could be therapeutic in these patients. Here we used a validated zebrafish model of DS, scn1lab homozygous mutants, to screen a commercially available library containing 370 synthetic cannabinoid (SC) compounds for compounds effective in reducing spontaneous seizures. Primary phenotype-based screening was performed using a locomotion-based assay in 96-well plates, and a secondary local field potential recording assay was then used to confirm suppression of electrographic epileptiform events. Identified SCs with anti-seizure activity, in both assays, included five SCs structurally classified as indole-based cannabinoids: JWH 018 N-(5-chloropentyl) analog, JWH 018 N-(2-methylbutyl) isomer, 5-fluoro PB-22 5-hydroxyisoquinoline isomer, 5-fluoro ADBICA, and AB-FUBINACA 3-fluorobenzyl isomer. Our approach demonstrates that two-stage phenotype-based screening in a zebrafish model of DS successfully identifies synthetic cannabinoids with anti-seizure activity, and supports further investigation of SCs for refractory epilepsies.

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NaV1.1 and NaV1.6 selective compounds reduce the behavior phenotype in a novel zebrafish model for Dravet Syndrome

10.1101/675082 ◽

2019 ◽

Author(s):

Wout J. Weuring ◽

Sakshi Singh ◽

Linda Volkers ◽

Martin Rook ◽

Ruben H. van ‘t Slot ◽

...

Keyword(s):

Treatment Strategies ◽

Epileptic Seizures ◽

Selective Inhibition ◽

Epileptic Encephalopathy ◽

Model Systems ◽

Dravet Syndrome ◽

Loss Of Function ◽

Zebrafish Model ◽

Neuronal Inhibition ◽

Increased Sensitivity

AbstractDravet syndrome is caused by dominant loss-of-function mutations in SCN1A which cause reduced activity of Nav1.1 leading to lack of neuronal inhibition. On the other hand, gain-of-function mutations in SCN8A can lead to a severe epileptic encephalopathy subtype by over activating NaV1.6 channels. These observations suggest that Nav1.1 and Nav1.6 represent two opposing sides of the neuronal balance between inhibition and activation. Here, we hypothesize that Dravet syndrome may be treated by either enhancing Nav1.1 or reducing Nav1.6 activity. To test this hypothesis we generated and characterized a novel DS zebrafish model and tested new compounds that selectively activate or inhibit the human NaV1.1 or NaV1.6 channel respectively. We used CRISPR/Cas9 to generate two separate Scn1Lab knockout lines as an alternative to previous knock-down models. Using an optimized locomotor assay, spontaneous burst movements were detected that were unique to Scn1Lab knockouts and disappear when introducing human SCN1A mRNA. Besides the behavioral phenotype, Scn1Lab knockouts show sudden, electrical discharges in the brain that indicate epileptic seizures in zebrafish. Scn1Lab knockouts showed increased sensitivity to the convulsant pentylenetetrazole and a reduction in whole organism GABA levels. Drug screenings further validated a Dravet syndrome phenotype. We tested the NaV1.1 activator AA43279 and our newly synthesized NaV1.6 inhibitors MV1369 and MV1312 in the Scn1Lab knockouts. Both type of compounds significantly reduced the number of burst movements. Our results show that selective inhibition of NaV1.6 could be just as efficient as selective activation of NaV1.1 and these approaches could prove to be novel potential treatment strategies for Dravet syndrome and other (genetic) epilepsies. Compounds tested in zebrafish however, should always be further validated in other model systems, preferably human derived.

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Large-Scale Phenotype-Based Antiepileptic Drug Screening in a Zebrafish Model of Dravet Syndrome

eNeuro ◽

10.1523/eneuro.0068-15.2015 ◽

2015 ◽

Vol 2 (4) ◽

pp. ENEURO.0068-15.2015 ◽

Cited By ~ 57

Author(s):

Matthew T. Dinday ◽

Scott C. Baraban

Keyword(s):

Antiepileptic Drug ◽

Drug Screening ◽

Large Scale ◽

Dravet Syndrome ◽

Zebrafish Model

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Efficacy of Fenfluramine and Norfenfluramine Enantiomers and Various Antiepileptic Drugs in a Zebrafish Model of Dravet Syndrome

Neurochemical Research ◽

10.1007/s11064-021-03358-2 ◽

2021 ◽

Author(s):

Jing Li ◽

Maxim Nelis ◽

Jo Sourbron ◽

Daniëlle Copmans ◽

Lieven Lagae ◽

...

Keyword(s):

Antiepileptic Drugs ◽

Parent Compound ◽

Treatment Algorithm ◽

Dravet Syndrome ◽

Racemic Mixture ◽

Preclinical Model ◽

Zebrafish Model ◽

Experimental Conditions ◽

Larval Zebrafish ◽

Kinetics Of

AbstractDravet syndrome (DS) is a rare genetic encephalopathy that is characterized by severe seizures and highly resistant to commonly used antiepileptic drugs (AEDs). In 2020, FDA has approved fenfluramine (FFA) for treatment of seizures associated with DS. However, the clinically used FFA is a racemic mixture (i.e. (±)-FFA), that is substantially metabolized to norfenfluramine (norFFA), and it is presently not known whether the efficacy of FFA is due to a single enantiomer of FFA, or to both, and whether the norFFA enantiomers also contribute significantly. In this study, the antiepileptic activity of enantiomers of FFA (i.e. (+)-FFA and (−)-FFA) and norFFA (i.e. (+)-norFFA and (−)-norFFA) was explored using the zebrafish scn1Lab−/− mutant model of DS. To validate the experimental conditions used, we assessed the activity of various AEDs typically used in the fight against DS, including combination therapy. Overall, our results are highly consistent with the treatment algorithm proposed by the updated current practice in the clinical management of DS. Our results show that (+)-FFA, (−)-FFA and (+)-norFFA displayed significant antiepileptic effects in the preclinical model, and thus can be considered as compounds actively contributing to the clinical efficacy of FFA. In case of (−)-norFFA, the results were less conclusive. We also investigated the uptake kinetics of the enantiomers of FFA and norFFA in larval zebrafish heads. The data show that the total uptake of each compound increased in a time-dependent fashion. A somewhat similar uptake was observed for the (+)-norFFA and (−)-norFFA, implying that the levo/dextrotation of the structure did not dramatically affect the uptake. Significantly, when comparing (+)-FFA with the less lipophilic (+)-norFFA, the data clearly show that the nor-metabolite of FFA is taken up less than the parent compound.

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