When facing a potential threat, zebrafish choose to continue mating rather than flee. This surprising response, different than that of some other species, appears to be controlled by specific brain regions that respond to pheromone cues.
These findings by scientists at Harvard University and Novartis Institutes of BioMedical Research (NIBR) illuminate an aspect of basic biology that will be important as researchers use zebrafish to model neurological diseases that affect social behavior, such as autism and schizophrenia. The study is published in Current Biology.
“Animals and people make behavioral decisions, ones controlled by environmental challenges and modulated by their internal drives, but little is known about the biology of these choices,” said Mark Fishman, Harvard professor of stem cell and regenerative biology and senior author of the study. “We looked at a critical decision for the survival of the species in zebrafish, giving them the choice between mating and fleeing a threat.”
To simulate a threat, the researchers used “skin extract,” a complicated mixture of pheromones that is released when a zebrafish is injured. When exposed to the substance, zebrafish usually show a strong alarm response, swimming quickly near the bottom of the tank and then freezing.
But when the zebrafish were mating, they ignored the threat. Moreover, they did not need to be mating to ignore the threat — being exposed to “mating water” that was previously conditioned by mating zebrafish was enough. This indicated to the researchers that the behavior was due to reproductive pheromones released in the water.