Anxiolytic effects of fluoxetine and nicotine exposure on exploratory behavior in zebrafish

Zebrafish (Danio rerio) have emerged as a popular model for studying pharmacological effects on behavior and anxiety. While there have been numerous studies documenting the anxiolytic and anxiogenic effects of common drugs in zebrafish, many do not report or test for behavioral differences between the sexes. Previous studies of zebrafish have indicated that males and females differ in their behavioral responses to anxiety. In this study, we test for sex-dependent effects of fluoxetine and nicotine. We exposed fish to system water (control), 10 mg/L fluoxetine, or 1 mg/L nicotine for three minutes prior to being subjected to four minutes in an open-field drop test. Video recordings were tracked using ProAnalyst. Fish from both drug treatments reduced swimming speed, increased vertical position, and increased use of the top half of the open field when compared with the control, though fluoxetine had a larger effect on depth related behaviors while nicotine mostly affected swimming speed. A significant sex effect was observed where females swam at a slower and more constant speed than males in all treatments. No interactions between sex and the drugs were observed across the entire study.