Validation of a larval zebrafish locomotor assay for discovery of GABAA-receptor modulators via HPLC-based activity profiling of extracts

Gamma aminobutyric acid type A (GABAA) receptors are the target for numerous clinically important drugs used to treat anxiety, insomnia and epilepsy. We previously identified a series of allosteric GABAA receptor agonists with the aid of HPLC-based activity profiling, whereby activity was tracked with an electrophysiological assay in Xenopus oocytes expressing GABAA receptors of desired subunit composition [1]. To accelerate the discovery process, we now established an approach for HPLC activity profiling using larval zebrafish seizure model [2] instead of Xenopus oocytes. The assay uses zebrafish larvae in a 96-well format, and automated tracking of larval movements with an IR-sensitive camera. Larval convulsions are provoked by the pro-convulsant GABAA receptor antagonist pentylenetetrazol (PTZ), and GABAA receptor agonistic extracts and compounds are identified through a decrease in locomotor activity.