Regulation of somatostatin-14 and gastrin I binding sites in rat gastrointestinal mucosa by ulcerogenic dose of cysteamine.

A single duodenal ulcerogenic dose of cysteamine administered into rats induced time-dependent depletion of immunoreactive somatostatin in the gastric corporeal, antral, and duodenal mucosa with a parallel increase (up-regulation) of somatostatin binding sites. The concentration of somatostatin binding sites returned to the control level in the corporeal mucosa when measured at 24 hrs; however, in the duodenal mucosa there was only a partial return to the control level. Somatostatin binding sites in the antral mucosa did not return to control level even after 24 hrs. Except for the duodenum mucosal immunoreactive gastrin level was unaffected by cysteamine administration, but corporeal mucosal gastrin I binding sites were diminished (down-regulation) after 24 hrs.