Stress is a perceived (psychological) condition posed by fears or outside events. Importantly, stress evokes adaptive responses which in return defends the stability of the internal environment. The immunity and gastrointestinal tract are particularly responsive to stress.
Stress shows both short and long term effects on the gastrointestinal tract as exposure to it may result in alternations of the brain-gut axis, leading to an array of gastrointestinal disorders including inflammatory bowel disease (IBD) or irritable bowel syndrome (IBS), gastroesophageal reflux disease (GERD), pectic ulcer and other functional gastrointestinal diseases.
The major effects on gut physiology are as follows:-
1) Alterations in gastrointestinal motility
2) Changes in the enzymatic secretion
3) Increase in mucosal permeability
4) Less regenerative capacity of the gastrointestinal mucosa and mucosal blood flow
5) Reduction of microbiota
6) Acute symptoms of stress are dyspepsia, diarrhoea or abdominal pain.
Diagnostic approach includes:
- Laboratory tests
- Imaging techniques (abdominal sonography), endoscopy (gastroscopy, colonoscopy, and small intestine endoscopy
The Brain-Gut-Axis (BGA)
The brain communicates with the gut through multiple parallel pathways such as the autonomic nervous system (ANS), the hypothalamic-pituitary-adrenal axis (HPA), and other connections as well. One such important coordinator between endocrine ad immune response to stress is a corticotrophin-releasing factor (CRF).
CRF is released in the hypothalamus, which further activates HPA as a response reaction, is the major step of endocrine response to stress. Secondly,
release of adrenocorticotropic hormone (ACTH) to stimulate the secretion of the stress hormone “cortisol” by the adrenal glands.
These are released in stressful situations leading to inflammation, increase in gut permeability and alternation in gut motility. There are other mechanisms which are stress-induced and lead to the pathway of other disorders. Therefore, the enteric nervous system referred to as the "second brain" relies on neurones and neurotransmitters of the central nervous system (brain and spinal cord). So, any disruption in signalling to the CNS leads to disturbances in the GI tract.
Alteration in Appetite-Regulating Hormones
Ghrelin and leptin, are two hormones responsible in appetite regulation, where Ghrelin (secreted from the stomach) is an appetite-stimulating hormone which promotes hunger, and leptin is the appetite-suppressing hormone which promotes a feeling of satiety and suppresses food intake.
A study done by Jaremlka et al, 2014, investigated the link between stress, appetite-controlling hormones and dietary intake in women. It was observed that women under interpersonal stress consume more comforting foods like carbohydrate-rich and fatty foods. This was believed to be due to the dysfunction in proper secretion of hormones, as ghrelin levels were high, which promoted overeating leading to weight gain and gastrointestinal disturbances.
In conclusion, exposure to chronic stress plays a role in altering the pathogenesis of Gastrointestinal disorders or diseases. Moreover, there is a link between stressful events and weight gain which further may lead to gastrointestinal disturbances.
References
Konturek (2011). STRESS AND THE GUT: PATHOPHYSIOLOGY, CLINICAL CONSEQUENCES, DIAGNOSTIC APPROACH AND TREATMENT OPTIONS JOURNAL OF PHYSIOLOGY AND PHARMACOLOGY.
Ariana M. Chao. Et al (2017).Stress, cortisol, and other appetite-related hormones: Prospective prediction of 6-month changes in food cravings and weight.Obesity (Silver Spring).
Jaremka et al, 2014.Interpersonal Stressors Predict Ghrelin and Leptin Levels in Women. Psychoneuroendocrinology.
