bdnf loss affects activity, sociability, and anxiety-like behaviour in zebrafish

Brain-derived neurotropic factor (BDNF) has established roles in neuronal survival and differentiation, in synaptic plasticity, and in neurotransmitters release. Several lines of evidence suggest that variations in BDNF might alter behaviour and contribute to neurobehavioural disorders. We investigated the functional effects of BDNF loss on behaviour by phenotyping a recently-generated CRISPR/Cas9 bdnf^-/- zebrafish line through a battery of behavioural assays. Results of two behavioural tests suggested higher levels of locomotor activity in bdnf^-/- zebrafish compared to bdnf^+/+ zebrafish, in spite of similar swimming capacities observed in the two lines in a swim tunnel. bdnf^-/- zebrafish also displayed higher levels of attraction towards a social stimulus compared to wild-type zebrafish, suggesting an effect of BDNF on sociability. Last, in a scototaxis test, we found evidence of potential differences in anxiety-like behaviour between the two lines. Our study supports an effect of BDNF on several behavioural traits, in line with early studies in mutant rodent models and in humans, suggesting the possibility to use the zebrafish to investigate diseases that involve alteration in BDNF levels.