Explaining the Enteric Nervous System

This article focuses on the role of the enteric nervous system (ENS) for overall health. The ENS is a system of cerebral nervous tissue which is in structure and function very similar to the brain. This is why the ENS is called the ‘The second brain’.

The ENS organises gastro intestinal function independently of the brain. Problems with the ENS can lead to digestive disorders and more specifically neurological disorders.

Research has found that brain related neurological disorders can also lead to ENS dysfunction. Disorders such as Autism, Amyotrophic lateral sclerosis, transmissible spongiform encephalopathies, Parkinson’s, Alzheimers, have ENS related dysfunction. (Nat Rev Gasteroenterol Hepatol 2016 Sep: 13(9): 517-28)

For other conditions such as migraine and epilepsy, the underlying cause of these disorders is not well known. Evidence is now suggesting that the function of the ENS is seen as related to these neurological conditions.

Any therapy that addresses the nervous system of the abdomen can be an additional adjunct to more traditional approaches. (J Altern Complement Med. 1999 Dec;5(6):575-86)

There is a gut-brain axis which is a two way communication channel from the brain to the ENS and back to the brain again. Emotional and cognitive areas of the brain are connected with intestinal functions of the gut.

Research is now suggesting that this communication channel is effected by gut micro biotics and effect the neural, endocrine, immune and humoral systems of the body. Poor two way communication pathways can lead to mental illness such as anxiety disorders and depression as well as GI disorders such as Irritable Bowel Syndrome.(Ann Gastroenterol. 2015 Apr-Jun;28(2):203-209)

In a study using rodents in a germ free environment, the gut microbiota appears to influence emotional behavior, stress and pain modulation systems as well as brain neuro-transmitter systems.

Further studies need to be done to translate these rodent studies to human physiology and to better understand diseases such as irritable bowel syndrome, autism, anxiety, depression and Parkinson’s disease.

The human microbiota are microbial species that live in the human body. They are made up of bacteria, viruses and funguses that call our bodies home.

Each of us harbour anywhere from 10 trillion to 100 trillion microbial cells, in a symbiotic relationship with our bodies. Estimates have stated that there could be 1000 different species of microorganisms that make up the human microbiota. Whilst numerous these organisms are very small and make up only 2-3% of our body weight.

These micro-organisms are important in both health and disease. Current research has found links between these bacterial populations and the following diseases: Asthma, Autism, Cancer, Celiac disease, Colitis, Diabetes, Eczema, Hear disease, Malnutrition, Multiple Sclerosis, Obesity.

The human microbiome has an effect on the following broad areas:

  • Nutrition,
  • Immunity,
  • Behaviour &
  • Disease. ( J Clin Invest. 2015 Mar 2;125(3):926-38)

The gut micro-biota is comprised of micro-organisms that reside in our gastro-intestinal ecosystem. Any alterations in the function of these effect not only gut related disorders, but also central nervous system based problems such as Alzheimer’s disease (AD). AD is a neuro-degenerative disorder that is associated with impaired cognition.

Imbalances in the gut microbiota can induce inflammation that is associated with pathogenesis of obesity, Type 2 Diabetes and AD.

Understanding the underlying mechanisms of enteric nervous system dysfunction can help to provide new insights into new strategies for treating AD. (J Alzheimers Dis. 2017 Mar 29)


  1. Rao M1and Gershon MD (2016) The bowel and beyond: the enteric nervous system in neurological disorders. Nat Rev Gastroenterol Hepatol.Sep;13(9):517-28
  1. Mcmilin DL et.al (1999) The abdominal brain and enteric nervous system. J Altern Complement Med. Dec;5(6):575-86
  1. Carabotti M et.al (2015) The gut-brain axis: interactions between enteric microbiota, central and enteric nervous systems. Ann Gastroenterol.Apr-Jun;28(2):203-209
  1. Mayer EA et. al (2015) Gut/brain axis and the microbiota. J Clin Invest. Mar 2;125(3):926-38
  1. Jiang C et. al. (2017). The Gut Microbiota and Alzheimer’s disease. J Alzheimers Dis Mar 29