Effects of ibuprofen, diclofenac and paracetamol on hatch and motor behavior in developing zebrafish (Danio rerio)

Non-steroidal anti-inflammatory drugs (NSAIDs) which are widely used as pain relief medicines are causing increasing environmental concern due to their incomplete removal in wastewater treatment plant and potential toxicity on endocrine, kidney and reproduction in teleost fish. This study focused on the effects of widely used ibuprofen, diclofenac and paracetamol on the hatch and motor ability of early-stage zebrafish, by exposing embryos to the target chemicals at 5, 50 and 500 μg/L starting from 6 h postfertilization (hpf). A significant reduction in hatch rate at 55 hpf was caused by both ibuprofen (-63%) and diclofenac (-58%) at 500 μg/L. Exposure to high concentration of ibuprofen significantly decreased the spontaneous movement by 25%, and reduced the free swimming distance, duration and speed under dark condition by 41%, 29% and 30%, respectively. High concentration of diclofenac also caused 23% decrease in spontaneous movement, and reduced the swimming distance as well as active duration by 17% and 13% under light stimulation. In comparison, the exposure to paracetamol did not cause any notable effect. Among neuron related genes tested, the expression of neurog1 was down-regulated from ibuprofen and diclofenac exposure by 19% and 26%, while the expression of neurod1 was up-regulated only by ibuprofen (31%). These findings indicated that ibuprofen and diclofenac significantly affected embryo locomotivity and were potentially neurotoxic, thus posing threats to zebrafish development.