A study published in PLOS Biology reveals that microorganisms play a crucial role in the social development of zebrafish by influencing neural pruning in their developing brains. Researchers from the University of Oregon found that germ-free zebrafish larvae, which lack microbiota early in development, exhibited inhibited social behavior and denser neural connections due to reduced activity of immune cells called microglia. The addition of intestinal bacteria restored normal social behavior and neural development, indicating that microbiota significantly impacts microglial activity and synaptic pruning.
The study utilized transparent zebrafish larvae to closely observe their neuronal and social development with or without their natural microbiota during the first week of life. Despite regaining microbiota after seven days, germ-free larvae showed persistent changes in brain structure and behavior by day 14. By genetically modifying microglia or introducing various bacterial groups, the researchers demonstrated that these microglia are vital for synaptic pruning and that an intact microbiota is essential for normal social development. The findings highlight a critical developmental window, underscoring the gut-brain connection in social behavior and neural remodeling in zebrafish.
