Stress And The Gut-Brain Axis

Brain Awareness Week 2023
Series 2 of 7
Stress and Gut-Brain Axis.
The microbiome-gut-brain axis is influenced by stress while the gut microbiota plays a significant role in regulating stress-related responses. When under short-term or chronic stress, brain axis stimulates the release of stress hormones, they alter the gut microbiome diversity, increase the pathogenic bacteria, increase intestinal permeability, decrease the production of beneficial metabolites and neurotransmitters in the gut, this further leads to aggravation of gastrointestinal diseases and in some cases other psychological conditions like anxiety, insomnia etc. . The gut-brain axis hence is a potential target for therapeutic strategies against stress related disorders.

Stress triggers, the amygdala, a key stress-related brain region to send a distress signal to the hypothalamus, which causes the release of stress hormones like cortisol, which impacts the gut by altering the gut microbiota phyla, slows digestion, microbial diversity, anxiety-like behaviour, increased intestinal permeability, and the set point for activation of the neuroendocrine hypothalamic-pituitary-adrenal (HPA) stress axis.
The activation of the vagus nerve, production of microbial antigens, production of microbial metabolites (i.e. short-chain fatty acids), and enteroendocrine signaling from gut epithelial cells. Through these routes of communication, the microbiota–gut–brain axis controls central physiological processes, such as neurotransmission, neurogenesis, neuroinflammation and neuroendocrine signaling that are all implicated in stress-related responses. Dysregulation of the gut microbiota subsequently leads to alterations in all of these central processes and potentially contributes to stress-related disorders.
Beyond stress-related dietary changes, it has been suggested that the physiological changes caused by stress impact bacterial populations.
Stress can drive and augment numerous gastrointestinal issues, including irritable bowel syndrome and multiple inflammatory bowel diseases.
Increases in concentrations of the stress hormones have been shown to increase the growth, virulence, and colonization of pathogenic bacteria.
Stress also alters the concentration of microbially produced vitamins or neurotransmitters in the gut is unknown.
Stress-induced gut inflammation could be a key mechanism for changes in emotional behavior under stress, with the gut microbiome function promoting or decreasing gut and systemic inflammation.
Several studies have shown that diets that modify the microbiota, probiotics, prebiotics ,and postbiotics can reduced stress-related behaviour and HPA activation.