PUBLICATION

Inhibition of glutamate decarboxylase (GAD) by ethyl ketopentenoate (EKP) induces treatment-resistant epileptic seizures in zebrafish

Authors

Zhang, Y., Vanmeert, M., Siekierska, A., Ny, A., John, J., Callewaert, G., Lescrinier, E., Dehaen, W., de Witte, P.A.M., Kaminski, R.M.

ID

ZDB-PUB-170805-2

Date

2017

Source

Scientific Reports 7: 7195 (Journal)

Registered Authors

Keywords

Epilepsy, High-throughput screening

MeSH Terms

Structure-Activity Relationship
Enzyme Inhibitors/chemistry
Enzyme Inhibitors/pharmacology*
Seizures/drug therapy
Seizures/genetics
Seizures/metabolism*
Seizures/physiopathology*
Animals
Molecular Conformation
Disease Models, Animal
Models, Molecular
Biomarkers
Gene Expression
Motor Activity
Gene Expression Regulation, Developmental
Behavior, Animal
Glutamate Decarboxylase/antagonists & inhibitors*
Glutamate Decarboxylase/chemistry
Glutamate Decarboxylase/genetics
Zebrafish

(all 20)

PubMed

28775328 Full text @ Sci. Rep.

Abstract

Epilepsy is a chronic brain disorder characterized by recurrent seizures due to abnormal, excessive and synchronous neuronal activities in the brain. It affects approximately 65 million people worldwide, one third of which are still estimated to suffer from refractory seizures. Glutamic acid decarboxylase (GAD) that converts glutamate into GABA is a key enzyme in the dynamic regulation of neural network excitability. Importantly, clinical evidence shows that lowered GAD activity is associated with several forms of epilepsy which are often treatment resistant. In the present study, we synthetized and explored the possibility of using ethyl ketopentenoate (EKP), a lipid-permeable GAD-inhibitor, to induce refractory seizures in zebrafish larvae. Our results demonstrate that EKP evoked robust convulsive locomotor activities, excessive epileptiform discharges and upregulated c-fos expression in zebrafish. Moreover, transgenic animals in which neuronal cells express apoaequorin, a Ca²⁺-sensitive bioluminescent photoprotein, displayed large luminescence signals indicating strong EKP-induced neuronal activation. Molecular docking data indicated that this proconvulsant activity resulted from the direct inhibition of both gad67 and gad65. Limited protective efficacy of tested anti-seizure drugs (ASDs) demonstrated a high level of treatment resistance of EKP-induced seizures. We conclude that the EKP zebrafish model can serve as a high-throughput platform for novel ASDs discovery.

Genes / Markers

Figures

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Expression

Phenotype

Fish	Conditions	Stage	Phenotype	Figure
WT	chemical treatment by environment: 2-oxopent-4-enoic acid	Days 7-13	larval locomotory behavior process quality, abnormal	Fig. 2
WT	chemical treatment by environment: 2-oxopent-4-enoic acid	Days 7-13	optic tectum action potential process quality, abnormal	Fig. 3
WT	chemical treatment by environment: 2-oxopent-4-enoic acid	Days 7-13	whole organism fosab expression increased amount, abnormal	Fig. 3
WT	chemical treatment by environment: 2-oxopent-4-enoic acid	Days 7-13	whole organism decreased life span, abnormal	Fig. 2
WT	chemical treatment by environment: 2-oxopent-4-enoic acid	Days 7-13	whole organism increased behavioural activity, abnormal	Fig. 2
WT	chemical treatment by environment: pentetrazol	Days 7-13	whole organism fosab expression increased amount, abnormal	Fig. 3
mitfa^w2/w2; zf2031Tg	chemical treatment by environment: 2-oxopent-4-enoic acid	Days 7-13	brain EGFP expression increased amount, abnormal	Fig. 4
mitfa^w2/w2; zf2031Tg	chemical treatment by environment: perampanel, chemical treatment by environment: 2-oxopent-4-enoic acid	Days 7-13	brain EGFP expression amount, ameliorated	Fig. 5
mitfa^w2/w2; zf2031Tg	chemical treatment by environment: perampanel, chemical treatment by environment: 2-oxopent-4-enoic acid	Days 7-13	larval locomotory behavior process quality, ameliorated	Fig. 5
mitfa^w2/w2; zf2031Tg	chemical treatment by environment: perampanel, chemical treatment by environment: 2-oxopent-4-enoic acid	Days 7-13	whole organism behavioural activity, ameliorated	Fig. 5

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Mutations / Transgenics

Allele	Construct	Type	Affected Genomic Region
w2		Point Mutation	mitfa
zf2031Tg	Tg(elavl3:EGFP-Aequorin)	Transgenic Insertion

Human Disease / Model

Human Disease	Fish	Conditions	Evidence
epilepsy	mitfa^w2/w2; zf2031Tg	chemical treatment by environment: 2-oxopent-4-enoic acid	TAS
epilepsy	AB	chemical treatment by environment: 2-oxopent-4-enoic acid	TAS

1 - 2 of 2

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Sequence Targeting Reagents

Fish

Fish
AB
mitfa^w2/w2; zf2031Tg
WT

Antibodies

Orthology

Engineered Foreign Genes

Marker	Marker Type	Name
Aequorin	EFG	Aequorin
EGFP	EFG	EGFP

Mapping

Zhang et al., 2017 ZDB-PUB-170805-2 PMID:28775328

Inhibition of glutamate decarboxylase (GAD) by ethyl ketopentenoate (EKP) induces treatment-resistant epileptic seizures in zebrafish

Zhang et al., 2017

ZDB-PUB-170805-2
PMID:28775328