#gi-tract

The gut–brain axis is a bidirectional communication system between the central nervous system (CNS) and the gastrointestinal tract.

Regulation of the microbiota–brain–gut axis is essential for maintaining homeostasis, including that of the CNS. A number of approaches have been used to probe this axis, including the use of germ-free animals, probiotic agents, antibiotics, or animals exposed to pathogenic bacterial infections.

Together, it is clear that the gut microbiota can be a key regulator of mood, cognition, pain, and obesity. Understanding microbiota–gut–brain communications is an exciting but challenging area of research that may contribute new insights into individual variations in cognition, personality, mood, sleep, and eating behavior and how they contribute to a range of neuropsychiatric diseases ranging from affective disorders to autism and schizophrenia.

Larger Inside

Like Doctor Who’s TARDIS, the gastro-intestinal tract – the tube running from your mouth to your bottom – is much bigger on the inside than it appears from the outside, and the entire surface area of this vital pipework is roughly the same as a small one-room flat. This impressive size is mostly due to microscopic ‘fingers’ called microvilli on the surface of cells in the small intestine – the purple frond-like structures in this image of human intestine cells, seen down a high-powered microscope. The green spots are clumps of a molecule called ANKS4B, which organises the microvilli into small clusters so they can function properly to absorb nutrients from food. Intriguingly, similar molecules are at work inside the inner ear, clustering together stereocilia – the hair-like fronds that convert soundwaves into nerve signals our brains interpret as sound – highlighting how similar processes are used around the body to get the job done.

Written by Kat Arney

Image from work by Scott W.Crawley and colleagues

Department of Cell and Developmental Biology, Vanderbilt University School of Medicine, Nashville, TN, USA

Image copyright Elsevier 2016

Published in Developmental Cell, January 2016