Sedative effect of u-49900 (3,4-dichloro-n-(2-(diethylamino)cyclohexyl)-n-methyl-benzamide) in adult zebrafish

U-49900 is a chemical analogue of a selective μ-opioid receptor agonist U-47700. Despite the growing abuse of synthetic opioids, including U-49900, its psychopharmacological and toxicological profiles remain poorly understood. The zebrafish (Danio rerio) is a promising model organism in neuroscience, and is often used for the psychopharmacological evaluation of neurotropic drugs. The psychopharmacological profile of U-49900 was evaluated here in adult zebrafish at 1, 5, 10 and 25 mg/l (water immersion) tested in the novel tank test. U-49900 at 25 mg/l for 20 min reduces the distance traveled and the number of top entries in the novel tank test (p0.001 vs. control group), but unalters other parameters in this test. Overall, the sensitivity of zebrafish to synthetic non-fentanyl opioids like U-49900 suggests the possibility of developing high-throughput screening platforms for finding effective therapies for pathological conditions caused by synthetic opioids.