An Illustration of the Human Digestive Tract
(Photo : OpenStax College via Wikimedia Commons) Illustration of the Human Digestive Tract from Anatomy & Physiology, Connexions website.

Neuroscientists refer to the "gut-brain-axis," or GBA is the bidirectional communication between the gut and the brain - helping explain how nervousness gives the feeling of having "butterflies in the stomach."

A better understanding of the mechanisms affecting GBA could offer insights and lead to medications for neurological mood disorders such as anxiety and depression, and auto-immune inflammatory diseases like irritable bowel syndrome.

Unfortunately, further understanding of how the GBA actually affects and relates to these conditions remains restricted by the lack of objective and measurable criteria - reliable biomarkers - that would define the presence of a medical condition. Until recently, medical disorders have been identified in patients who reported common symptoms associated with those conditions.

An Illustration of the Human Digestive Tract
(Photo: OpenStax College via Wikimedia Commons)
Illustration of the Human Digestive Tract from Anatomy & Physiology, Connexions website.

Observing the Physical Link Between Brain and Gut

A number of previous works have led scientists to believe that serotonin might have something to do with a number of GBA-related disorders. Serotonin, known as the "happy chemical," is a neurotransmitter that sends signals to the nervous system through the vagus nerve, which generally interfaces the nervous system to a number of involuntary muscles - heart, lungs, and the digestive tract.

Although serotonin is mainly in the brain, a large part of our supply of the chemical transmitter is actually found within gut linings. Additionally, the production of the chemical seems to be affected by the bacterial "microbiome," or the concentration of different bacteria in the gut.

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The gut and the microbes housed in it play a role in keeping homeostasis - a stable internal state despite changes in the external environment - by supporting the immune system. This microbiome helps in the immune and inflammatory response by controlling what is absorbed and what is rejected and later excreted.

For example, the inflammatory toxin lipopolysaccharide (LPS) is generated by certain cultures of gut bacteria. It can trigger an inflammatory response if too much of the toxin spill from the gut into the bloodstream. A previous study has established that inflammation, and the presence of high concentrations of LPS in the blood, might be related with a number of mental health disorders such as depression, dementia, and schizophrenia.

 


Moving Towards Understanding GBA Conditions

An interdisciplinary team from the University of Maryland (UMD), with million-dollar support from the National Science Foundation, has developed a platform that monitors and generates a model of gut microbiome serotonin activity. The UMD team, which included neuroscientists, microbiologists, engineers, and physicists, is aiming to integrate the platform into a small, ingestible medium that can detect, monitor, and possibly treat GBA-related disorders.

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Professor Reza Ghodssi, the principal investigator of the UMD team, stressed the importance of different disciplines in their work. He said: "This enables us to measure and investigate data at the interface of each junction of a simulated GBA platform-cell to cell, cell to molecule, molecule to nerve-and develop engineering methodologies to analyze and interpret it."

Their recent work builds on earlier efforts to create ingestible medical devices by the UMD MEMS Sensors and Actuators Laboratory, the Brain and Behavior Initiative, and the Fischell Department of Bioengineering.


Check out more news and information on Gut Bacteria in Science Times.