by Dr. Meenakshy Varier on  December 30, 2016 at 10:36 AM Health Watch
  • Serotonin is a neurotransmitter that influences brain and bowel functions.
  • The gut microbes affect the human physiology by controlling the serotonin levels with the help of a protein known as TLR2.

The microbes found in the gut can interfere with human physiology by regulating the serotonin transporter activity.

Recent evidence suggest that gut microbiota influence the physical health and mental health. The complex community of trillions of microorganisms living in the gut also play a role in causing Parkinson's Disease.
How Gut Microbes Influence Brain Functions
How Gut Microbes Influence Brain Functions

Scientists at the University of Exeter Medical School and University of Zaragoza in Spain studied a protein known as TLR2, a critical detector of the microbiota found in the intestine.

This study shows that TLR2 also alters the availability of serotonin. Serotonin is a neurotransmitter that carries messages to the brain and is also found in the gut, where it regulates the bowel routines.

Its availability is important in a range of conditions from depression to inflammatory bowel diseases.

The research found that microbiota can affect the human physiology by interfering with the serotonin transporter activity, controlling its levels. Serotonin transporter is a target for numerous diseases. This was proven via research carried out in cells cultures and verified in mice.

Inflammatory Bowel Disease

Inflammatory bowel disease (IBD) is a term mainly used to describe two conditions, ulcerative colitis and Crohn's disease.

Both ulcerative colitis and Crohn's disease are chronic conditions that involve inflammation of the gut. Ulcerative colitis only affects the large intestine, while Crohn's disease can affect all of the digestive system, from the mouth to the anus.

It is estimated that IBD affects about one in every 250 adults in the UK. There are around 146,000 people with ulcerative colitis and 115,000 with Crohn's disease in the UK.

IBD is usually diagnosed in people in their late teens or early 20s, but can affect people of any age. IBD is more common in white people than in black people or those of Asian origin..


Inflammatory bowel disease is thought to be triggered when TLR2 is not functioning properly, but so far, the mechanisms behind this have not been fully understood. This study aimed to further this connection.

Dr Eva Latorre, a postdoctoral researcher at the University of Exeter Medical School, said "This paper has concluded that the protein TLR2 alters the availability of serotonin, which is important in a range of conditions from depression to inflammatory bowel disease. It is early days in this research though. We need to understand much more about the relationship between the microbiota in our guts and how they interact, before we can hope to harness effective new treatments."

When researchers examined human cells in a model of the intestine in the laboratory, they found that TLR2 controls serotonin transporter - obtaining the same result in studies on mice.

Principal investigator of this study, Professor José E Mesonero, at the University of Zaragoza, said: "This paper opens our minds about the complex universe of this forgotten organ: the microbiome. We have concluded that TLR2 not only can detect microbiota, but also modulate serotonin transport, one of the crucial mechanism in neurological and inflammatory diseases."

Though further research is imperative, this work can improve the basic understanding about the connection between gut and brain through microbiota.

The study was supported by the Foundation for the Study of Inflammatory Bowel Diseases in Aragón (ARAINF), in Spain and the finding is published in PLOS ONE.


  1. Inflammatory Bowel Disease - (
  2. José E Mesonero et al. Intestinal Serotonin Transporter Inhibition by Toll-Like Receptor 2 Activation. A Feedback Modulation. PLOS ONE; (2016)

Source: Medindia

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