The Simplified Guide to the Gut-Brain Axis – How the Gut and The Brain Talk to Each Other

Posted on June 27, 2017
Time to read: 10–12 minutes

The gut-brain axis (GBA) is a bidirectional link between the central nervous system (CNS) and the enteric nervous system (ENS) of the body. It involves direct and indirect pathways between cognitive and emotional centres in the brain with peripheral intestinal functions. The GBA involves complex crosstalk between the endocrine (hypothalamic-pituitary-adrenal axis), immune (cytokine and chemokines) and the autonomic nervous system (ANS).

The GBA primarily combines the sympathetic and parasympathetic arms of the autonomic nervous system (ANS), which drives both afferent and efferent neural signals between the gut and the brain, respectively. The HPA axis meanwhile coordinates adaptive responses against stress including activation of memory and emotional centres in the limbic system of the brain.

The neuro-immuno-endocrine mediators of the GBA allow the brain to influence intestinal function (immune cells, epithelial cells, enteric neurons, and smooth muscle cells). Moreover, the cells of the gastrointestinal (GI) tract are also under the influence of the gut microbiota and recent evidence suggests that there is an emerging concept whereby the microbiome plays an important role in the GBA structure. [1]


6. Role of gut microbiota in the production of free catecholamines

Asano Y, et al., Critical role of gut microbiota in the production of biological active, free catecholamines in the gut lumen of mice. American Journal of Physiology. 2012

10. Gut Brain Axis and Autism

Hsaio E et al., The microbiota modulates gut physiology and behavioral abnormalities associated with autism. Cell. 2014

13. Gut Microbiome and GABA modulation

Bravo J et al., Ingestion of Lactobacillus strain regulates emotional behavior and central GABA receptor expression in a mouse via the vagus nerve. PNAS. 2011

5 (100%) 1 vote
  • elliotmarques

    A useful breakdown of scientific concepts for a lay audience. I do have one obvious correction on first glance.

    You state: ‘Within the gut, the bacterial species Firmicutes and Bacteroides are approximately 75% of the gut microbiota and both of these species are very sensitive to change’

    What you mean to refer to are not species but PHYLA (These phyla contain potentially thousands of separate species). Additionally, you also mean to refer to ‘Bacteroidetes’, which is the relevant phyla, Bacteroides being a genus within that phyla.

    • Psychscenehub

      Wow! thanks for that detailed eye. Will make the change.