High-throughput Screening in Larval Zebrafish Identifies Novel Potent Sedative-hypnotics

Area of Science:

• Pharmacology
• Neuroscience
• Drug Discovery

Background:

• Traditional discovery of sedative-hypnotics relies on empirical methods.
• Existing drug screens often exclude animal models, limiting the scope of discovered compounds.
• A novel, efficient, and animal-based screening approach is needed to identify new sedative-hypnotics.

Purpose of the Study:

• To develop and validate a high-throughput screening assay using zebrafish larvae for identifying novel sedative-hypnotic compounds.
• To compare the efficacy of the zebrafish larvae assay with traditional tadpole assays.
• To discover and characterize new sedative-hypnotic agents from a compound library.

Main Methods:

• A computerized photomotor response assay was developed for zebrafish larvae, capable of tracking up to 96 animals simultaneously.
• The assay was validated against tadpole loss of righting reflexes using known sedative-hypnotics.
• A library subset of 374 compounds was screened for hypnotic activity, and identified hits were further investigated for their molecular mechanisms.

Main Results:

• The zebrafish larvae assay demonstrated high agreement (100%) and similar potency correlation (r > 0.999) with tadpole assays.
• Zebrafish assays required significantly less drug, time, and effort compared to tadpole assays.
• Two novel, potent, and reversible sedative-hypnotics (CMLD003237 and CMLD006025) were identified, with distinct molecular targets including GABA-A, nicotinic, and NMDA receptors.

Conclusions:

• Zebrafish larvae photomotor response assays provide a mechanism-independent platform for high-throughput screening of novel sedative-hypnotics.
• This approach significantly enhances the efficiency and scope of drug discovery for sedative-hypnotic agents.
• The diversity of chemical structures capable of inducing hypnosis is likely greater than currently recognized.