V. ALTOUNIAN/SCIENCE TRANSLATIONAL MEDICINEThe brain—the most exalted and enigmatic of organs, which is closed off from the rest of the body by a largely impermeable barrier—could not seem more disconnected from the intestine. Yet, according to a paper published today (November 19) in Science Translational Medicine, it’s thanks to the contents of the gut—specifically, the resident bacteria—that the mouse brain’s impermeable barrier develops properly, both before and after birth.
“It’s absolutely fascinating to think that gut bacteria can control permeability of the blood-brain barrier,” said Caltech microbiologist Sarkis Mazmanian who was not involved in the study. “Many neuroscientists staunchly believe that the blood-brain barrier is an incredibly impermeable membrane to many molecules and . . . would hardly believe that gut bacteria would control such an integral part of our neurobiology.”
The blood-brain barrier (BBB), which shields the organ from blood-borne infections, toxins, and more, is created by steadfast connections called tight junctions between the endothelial cells that line its blood vessels. So effective is the barrier that most proteins and molecules cannot pass through; those that do generally require selective transport via specific receptors.
A similar barrier—made up of epithelial cells and tight ...
