The smell of “anxiety”: Behavioral modulation by experimental anosmia in zebrafish

• Intact and sham-anosmic fish showed similar behaviors and whole-body cortisol levels.
• Fluoxetine exposed fish displayed a robust anxiolytic-like effect.
• There were no differences in all parameters analyzed in the anosmic fish.
• Anosmia triggers anxiety-like behaviors in zebrafish.
• Experimentally-evoked anosmia modulates anxiety-like behaviors in adult zebrafish.

Olfaction is strongly involved in the regulation of fish behavior, including reproductive, defensive, social and migration behaviors. In fish, anosmia (the lack of olfaction) can be induced experimentally, impairing their ability to respond to various olfactory stimuli. Here, we examine the effects of experimental lidocaine-induced anosmia on anxiety-like behavior and whole-body cortisol levels in adult zebrafish (Danio rerio). We show that experimentally-induced anosmia reduces anxiolytic-like behavioral effects of fluoxetine and seems to interact with anxiogenic effect of stress also paralleling cortisol responses in zebrafish. These findings provide first experimental evidence that temporary anosmia modulates anxiety-like behaviors and physiology in adult zebrafish.