If you’ve ever felt nauseous before an important presentation, or foggy after a big meal, then you know the power of the gut-brain connection.
Scientists now believe that a surprising array of conditions, from appetite disorders and obesity to arthritis and depression, may get their start in the gut. But it hasn’t been clear how messages in this so-called “second brain” spread from our stomachs to our cerebrum. For decades, researchers believed that hormones in the bloodstream were the indirect channel between the gut and the brain.
Recent research suggests the lines of communication behind that “gut feeling” is more direct and speedy than a diffusion of hormones. Using a rabies virus jacked up with green fluorescence, Duke researchers traced a signal as it traveled from the intestines to the brainstem of mice. They were shocked to see the signal cross a single synapse in under 100 milliseconds -- that’s faster than the blink of an eye.
“Scientists talk about appetite in terms of minutes to hours. Here we are talking about seconds," said Diego Bohórquez, Ph.D., senior author of the study and assistant professor of medicine at Duke University School of Medicine. “That has profound implications for our understanding of appetite. Many of the appetite suppressants that have been developed target slow-acting hormones, not fast-acting synapses. And that’s probably why most of them have failed.”