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Irritable bowel syndrome - Pathogenesis
Last reviewed: 04.07.2025
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In the pathogenesis of irritable bowel syndrome, the leading role is played by "disruption of the central and autonomic nervous system in the form of changes in the neurohumoral regulation of the functional state of the intestine, including its response to stress." Under the influence of etiological factors, primarily psychoemotional stress situations, there is a change in the sensitivity threshold of visceral receptors that determine pain perception, motor-evacuation dysfunction of the intestine. A major role in the development of irritable bowel syndrome is played by dysfunction of the gastrointestinal endocrine system and an imbalance in the production of hormones that affect the motor activity of the large intestine (cholecystokinin, somatostatin, vasoactive intestinal polypeptide, neurotensin, etc.). In particular, a decrease in the content of motilin in the plasma (it stimulates the motor-evacuation function of the intestine) was found in patients with irritable bowel syndrome.
An important role is played by the imbalance of biologically active substances involved in the regulation of intestinal function (serotonin, histamine, bradykinin, cholecystokinin, neurotensin, vasoactive intestinal polypeptide, enkephalins and endorphins). A certain role in the etiology is played by the regime and nature of nutrition. Irregular food intake, the predominance of refined products lead to a change in the motor-evacuation function of the intestine, microflora, and an increase in intra-intestinal pressure. Acute intestinal infections may be important in the development of irritable bowel syndrome.
Motility disorders can be either hyper- or hypodynamic, and they can alternate. In addition to impaired motility, visceral hypersensitivity of the intestine plays an important role in the pathogenesis of irritable bowel syndrome.
Recently, much attention has been paid not so much to changes in the concentration of intestinal hormones in the blood, but to the increased sensitivity of intestinal receptors to hormonal influences.
The role of endogenous opioid peptides - enkephalins, which have a significant effect on intestinal motility and secretion through opioid receptors, as well as on pain perception, in the development of irritable bowel syndrome has also been established. Endogenous opioid peptides enhance contractions of the colon.
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