In a groundbreaking study that reshapes our understanding of gut-brain communication researchers at Duke University School of Medicine have identified a neurobiotic sense a newly discovered system enabling the brain to respond instantly to signals from gut microbes.

Led by neurobiologists Dr. Diego Bohórquez and Dr. M. Maya Kaelberer and published in Nature the research focuses on neuropods specialized sensor cells in the colon lining. These cells detect microbial signals particularly a common bacterial protein called flagellin and rapidly transmit messages to the brain via the vagus nerve. This real-time signaling can influence appetite and food choices.

Flagellin, found in the tail-like flagella that help bacteria move is released during digestion. Neuropods recognize it using a receptor called TLR5, triggering a neural response rather than a slow immune reaction. According to Bohórquez this discovery could open new avenues for understanding how gut microbes impact not just eating behavior but also mood and potentially how the brain influences the microbiome in return.

With support from the National Institutes of Health the research team proposed a bold hypothesis: proteins from gut bacteria could directly activate neuropods to send appetite-suppressing signals to the brain demonstrating a microbial influence on behavior.

To test this, they fasted mice overnight and then introduced a small amount of flagellin into their colons. The result? The mice ate less. However when the same experiment was performed on mice lacking the TLR5 receptor their eating behavior remained unchanged they continued eating and gained weight.

The experiments revealed that interfering with this gut-brain signaling pathway directly affected how much the mice ate highlighting a stronger connection between gut microbes and behavior than previously understood.

This research offers a valuable foundation for the wider scientific community to explore how microbes shape our behavior said Dr. Bohórquez. A crucial next step is to study how different diets alter the gut microbiome which may be central to understanding and addressing conditions like obesity and psychiatric disorders.

The researchers focused on flagellin from Salmonella Typhimurium a known pathogen but not all flagellins are the same. Different bacterial species produce distinct forms, some harmful others naturally occurring and beneficial parts of the gut microbiome.

This complexity makes the discovery even more intriguing. The newly identified neurobiotic sense enables the brain to detect and respond to a wide variety of microbial signals from the gut each potentially shaping appetite mood and behavior.

Source: https://medschool.duke.edu/stories/newly-discovered-sixth-sense-links-gut-microbes-brain-real-time