The association of pyloric antral tissue levels of 5-hydroxytryptamine and restraint stress ulceration in the rat.

To determine the possible role of 5-hydroxytryptamine (5-HT) in the formation of restraint ulcerations, we investigated the relationship among mucosal tissue levels of 5-HT, vagotomy, and restraint ulcerations. Three murine experimental groups and one control group were used to compare the ulcerogenic effects of restraint with and without prior vagotomy. Ulcers were graded as to frequency, size, and hemorrhage on a 0-4+ scale. 5HT was measured in the gastric mucosa of each animal. Restraint caused significant ulcerations. The mean tissue level of 5-HT was significantly higher in the group with marked ulcerations (p less than 0.001). Our data suggest an increased cellular production of 5-HT during the development of the restraint ulcers. Vagotomy protected the animals against restraint ulcerations without depleting the baseline levels of 5-HT. Previous experiments have shown that urine levels of 5-hydroxyindoleacetic acid (5-HIAA) increase during the restraint period. Thus, increased tissue and urine levels of 5-HT appear to coincide with the development of restraint stress ulcers in the rat. Accordingly, if the coincidence occurs in humans, the measurement of urinary levels of 5-HIAA may be an indirect means of determining those patients at high risk for the development of stress ulcers.