[Role of serotonin in the pathogenesis of ulcer development]

The method of Okabe was used to induce experimental gastric ulcer in rats. The content of serotonin and histamine was determined in gastric mucosa extracts. The spectrum of proteolytic enzymes and proteolytic activity in gastric mucosa extracts were determined by polyacrylamide gel disc electrophoresis at varying pH. It was found that in "acetate" gastric ulcer the rats had the increased content of serotonin in the gastric mucosa followed by the elevated histamine content. In the early stages of "acetate" ulcer the proteolytic activity was detectable at pH 6.5-7. At the same time there took place a reconstruction of the spectrum of proteolytic enzymes. Analogous changes in the spectrum of proteolytic enzymes of gastric mucosa extracts and occurrence of the proteolytic activity at pH 6.5-7 were also recorded after serotonin administration (30 mg/kg) to intact rats. Thus it has been demonstrated that the increased serotonin output is implicated in the changes seen in the enzymatic spectrum and in the occurrence of proteolytic activity at high pH (6.5-7). The latter might be related to the release of lysosomal proteases responsible for intratissular proteolysis in the gastric mucosa and for ulcer formation.