ZeEfficacy – Efficacy Services

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Epilepsy Model

Epilepsy is characterized by recurrent, unprovoked seizures that result from excessive and hypersynchronous electrical discharges in the brain. Exposure to the common convulsant agent pentylenetetrazole (PTZ) induces a stereotyped and concentration-dependent sequence of behavioral changes culminating in convulsions in zebrafish larvae. This model allows identifying compounds that prevent locomotor and convulsive behavioral alterations.

Applications

  • Study the causes and mechanisms of seizures.
  • High throughput screening of new anti-epileptic or anticonvulsant drugs.

Advantages

High conservation of zebrafish convulsive behavioral responses with mammals.

Zebrafish exposure to PTZ induces similar results in mammals physiologically and behaviourally, but thanks to the large zebrafish progenies we can test a high number of compounds simultaneously.

Automated locomotion monitoring rapidly highlights epilepsy phenotype rescue, identifying promising therapeutic compounds.

Method description

Zebrafish embryos are exposed to PTZ, to unchain seizures, together with the compound of interest. Behavior and seizures are assessed in treated larvae using the following experimental protocol to evaluate the anticonvulsant properties of compounds:

Figure 1. Experimental design.

Readouts

  • Toxicity: determination of Lethal Concentration 50 (LC50), Benchmark Dose (BMD) and mortality at 120 hpf.
  • Locomotion activity: total distance moved, locomotion pattern and visual stimuli response.
  • Convulsive response: seizures can be evaluated as a response to a flashlight. These are evaluated through velocity and angle turn parameters. 

Larval movement is traced and analyzed by DanioVision™ software (Noldus IT).

Figure 2. Epileptic readouts measurements. From left to right: Total distance moved, Angle Turn, and Maximum Velocity in response to flashlight (seizure characterization). PTZ-treated larvae show a strong locomotion activity increase and the appearance of seizures (increased Angle turns and Max Velocity) compared to control siblings. The observed phenotype can be rescued by anti-convulsive compounds.