Molecular and behavioral responses of zebrafish embryos/larvae after sertraline exposure

Sertraline (SER) is one of the most frequently detected antidepressant drugs in aquatic environments. However, knowledge regarding SER-induced behavioral alterations in fish is insufficient, as well as the mechanisms underlying SER-induced toxicity. The present study aimed to determine behavioral and molecular responses in larval fish following SER exposure with a focus on its mode of action. Zebrafish embryos (similar to 6 h-post-fertilization, hpf) were exposed to one of three concentrations of SER (1, 10, 100 mu g/L) for 6 days, respectively. Evaluated parameters included development, behavior, transcripts related to serotonin signaling, serotonin levels, and acetylcholinesterase activity. Accelerated hatching of zebrafish embryos was observed for those fish exposed to 100 mu g/L SER at 54 hpf. Locomotor activity (e.g. distance moved and mobile cumulative duration) was significantly reduced in larval zebrafish following exposure to 10 and 100 mu g/L SER. Conversely, larval fish showed increased dark-avoidance after exposure to 1-100 mu g/L SER. Of the measured transcripts related to serotonin signaling, only serotonin transporter (serta) and serotonin receptor 2c (5-ht2c) mRNA levels were increased in fish in response to 10 mu g/L SER treatment. However, serotonin levels were unaltered in larvae exposed to SER. There were no differences among groups in acetylcholinesterase activity at any concentration tested. Taking together, the results evidenced that exposure to SER alters behavioral responses in early-staged zebrafish, which may be related to the abnormal expression of 5-ht2c. This study elucidates molecular responses to SER and characterizes targets that may be sensitive to antidepressant pharmaceuticals in larval fish.

Automated summary

The study investigated the behavioral and molecular responses in larval fish following exposure to different concentrations of SER. It was found that exposure to SER altered the behavior of early-stage zebrafish, with changes in locomotor activity and dark-avoidance. Additionally, an increase in mRNA levels of serotonin transporter and serotonin receptor 2c was observed in fish exposed to 10 μg/L SER.