Zebrafish: A Predictive Model for Assessing Seizure Liability - Zebrafish: Methods for Assessing Drug Safety and Toxicity - page 161

13.1.3 Zebrafish Seizure Liability Model
Several recent studies describe use of a zebrafish seizure model for drug screening
(Baraban et al., 2005; Berghmans et al., 2007; Winter et al., 2008). In these studies,
after treatment with PTZ, a potent proconvulsant, and other seizure inducing drugs,
zebrafish movement was quantified using automated motion detection systems,
including EthoVision (Noldus Information Technology) or VideoTrack (ViewPoint
Life Sciences). Three distinct stages of seizure-like behavior were observed: (1) in-
creased total movement, (2) whirlpool-like high-speed movement, and (3) loss of
normal body orientation and immobilization, resembling a clonic seizure (Baraban
et al., 2005; Berghmans et al., 2007; Winter et al., 2008). Both increased total
movement and whirlpool-like high-speed movement were observed after treatment
with PTZ concentrations between 2.5 and 15mM and loss of normal body orientation
and immobilization were observed after treatment with 15mM (Baraban et al., 2005;
Berghmans et al., 2007; Winter et al., 2008). Winter et al. (2008) reasoned that D at
high speed (greater than 20mm/s) in zebrafish could be used to predict compound-
induced seizures in humans; using this parameter, nonspecific movement unrelated to
compound-induced seizure-like activity was eliminated. Further confirming that
high-speed movement in zebrafish was predictive of seizures in humans, after PTZ
treatment, zebrafish EEG recordings revealed ictal spike-wave discharges, similar to
those observed in epilepsy patients (Baraban et al., 2005).
Use of video-based motion detection for assessing zebrafish behavior has now
been adapted for several additional end points, including neurons (Chapter 10),
muscles (Chapter 18), and overall development (Chapter 12). These highly versatile
systems will make it possible to validate use of zebrafish motility for a wide variety of
toxicity, safety, and efficacy studies.
13.2 MATERIALS AND METHODS
13.2.1 Embryo Handling
Phylonix AB zebrafish were generated by natural pairwise mating in our aquaculture
facility. Four to five pairs were set up for each mating; on average, 50-100 embryos
per pair were generated. Embryos were maintained in embryo water (5 g of Instant
Ocean Salt with 3 g of CaSO 4 in 25 L of distilled water) at 28 C for approximately
24 h before sorting for viability. The seizure assay was performed using 6dpf
zebrafish. Because the early-stage embryo receives nourishment from an attached
yolk sac, no additional maintenance was required.
13.2.2 Recording Zebrafish Movement Using
a Motion Detector
To analyze zebrafish movement, we used a video motion tracking device (VideoTrack
System, ViewPoint Life Sciences, Lyons, France). This instrument, adapted for