Effects of Fluoxetine on Anxiety-Like Behaviours of Zebrafish (Danio Rerio)

The zebrafish (Danio rerio) has emerged as a powerful model organism for studying anxiety. In this regard, a host of anxiolytic agents are available for testing, including fluoxetine - a selective serotonin reuptake inhibitor (SSRI). Adult wild-type zebrafish were used in this study which was approved by the Institutional Animal Use and Care Committee of St. Mary’s College of Maryland. Fluoxetinetreated and control groups underwent a startle cue test which consisted of three-time intervals: pre-stimulus, stimulus and poststimulus. Average proportion of time spent in the top half of the tank, and the average number of erratic movements were assessed. The difference between the average proportion of time spent in the top half of the tank was significantly different between the fluoxetine and control groups (t (22) = 2.074, p ˂ 0.05). In the fluoxetine group, there was a statistical difference between the proportion of time spent in the top half of the tank during the pre-stimulus, stimulus, and post stimulus intervals for both fluoxetine [F (2,11) = 3.98, p = 0.004] and control groups [F (2,11) = 3.98, p = 0.004]. Analysis of the average number of erratic movements revealed no statistical difference between the means of the fluoxetine and control groups. However, differences were observed in the average number of erratic movements between the three intervals of the startle cue test for both the fluoxetine and control groups (p =0.005, p = 0.001). Fluoxetine was therefore shown to exert anxiolytic effects on a stereotypic anxiety-like behaviour of the zebrafish. This provides proofof-principle for the behavioural assay involving a looming cue to evoke anxiety-like behaviour in this model animal.