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Irritable bowel syndrome: pathogenesis
Last reviewed: 23.04.2024
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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 reaction to stress." Under the influence of etiological factors, especially psychoemotional stress situations, there is a change in the sensitivity threshold of the visceral receptors determining the perception of pain, motor-evacuation dysfunction of the intestine. A major role in the development of irritable bowel syndrome is played by the dysfunction of the gastrointestinal endocrine system and imbalance in the production of hormones that affect the motor activity of the large intestine (cholecystokinin, somatostatin, vasoactive intestinal polypeptide, neurotensin, etc.). In particular, in patients with irritable bowel syndrome, a decrease in the content of motilin in the plasma (it stimulates the motor-evacuation function of the intestine) is found.
An important role is played by the imbalance of the biologically active substances involved in the regulation of bowel 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 intake of food, the predominance of refined products lead to a change in motor-evacuation function of the intestine, microflora, increased intestinal pressure. In the development of irritable bowel syndrome, acute intestinal infections may be important.
Disturbances of motility can be both in hyper- and hypodynamic type, and they can alternate. In addition to impaired motor function, the visceral hypersensitivity of the intestine plays an important role in the pathogenesis of irritable bowel syndrome.
Recently, great importance is given not so much to the change in the concentration of intestinal hormones in the blood, as to the increased sensitivity of the intestinal receptors to hormonal effects.
The role in the development of irritable bowel syndrome of endogenous opioid peptides - enkephalins, which have a significant effect on the motility and secretion of the intestine through opioid receptors, as well as on the perception of pain. Endogenous opioid peptides increase contraction of the large intestine.
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