Abstract

Background: Serotonin plays the role of critical signal molecule in great number of physiologic processes and pathologic symptoms of gastrointestinal tract. As a gastrointestinal hormone serotonin takes place in the regulation of smooth muscle motor activity and glandular secretion. It affects the gastrointestinal sensation of pain, nausea and vomiting. The aim of our study is to determine the presence and localization of serotonin-producing EC cells and distribution of serotonin receptor 5-HTR3 in the human stomach.
Material and methods: Biopsy specimens from 25 patients aged 40-70 years: body and antral part of the stomach are studied by immunohistochemical reactions for serotonin, serotonin receptor 5-HTR3; and transmission electron microscopy.
Results: The serotonin-producing cells are found between columnar cells of gastric epithelium, in the fundic and pyloric glands of the gastric mucosa. Their ultrastructural characteristics show the presence of EC1 and EC2 enterochromaffin cells. The expression of serotonin receptor 5-HTR3 in covering epithelium, glandular and interstitial cells shows the possibility serotonin to affect gastric mucosa secretion. The intensive expression of 5-HTR3 receptors in gastric wall smooth muscle cells demonstrates the key role of serotonin in gastrointestinal motility.
Conclusion: In order to obtain a better understanding of the functional role of serotonin, we investigate the localization of serotonin-producing EC cells, their ultrastructural characteristics and the presence and distribution of serotonin receptor 5HTR3 in the stomach. Enzymes needed for serotonin secretion and degradation, its transporters, as it great numbers of receptors are the base new drugs to be synthesized aiding clinical practice in gastroenterology.

Keywords: Gastric mucosa secretion; Gastrointestinal motility; Enterochromaffin cells; Serotonin; Serotonin receptors