Research reportMicrobial modulation of behavior and stress responses in zebrafish larvae

- Microbiota modulates anxiety-related behavior in zebrafish larvae.
- Larval stress responses are dramatically blunted in absence of microbiota.
- L. plantarum attenuates anxiety-related behavior in conventionally-raised larvae.
- Zebrafish larvae are a valuable tool for research on the gut-brain axis.

The influence of the microbiota on behavior and stress responses is poorly understood. Zebrafish larvae have unique characteristics that are advantageous for neuroimmune research, however, they are currently underutilized for such studies. Here, we used germ-free zebrafish to determine the effects of the microbiota on behavior and stress testing. The absence of a microbiota dramatically altered locomotor and anxiety-related behavior. Additionally, characteristic responses to an acute stressor were also obliterated in larvae lacking exposure to microbes. Lastly, treatment with the probiotic Lactobacillus plantarum was sufficient to attenuate anxiety-related behavior in conventionally-raised zebrafish larvae. These results underscore the importance of the microbiota in communicating to the CNS via the microbiome-gut-brain axis and set a foundation for using zebrafish larvae for neuroimmune research.