A possible role for 5-hydroxytryptamine as a mediator for calcitonin actions on the gastrointestinal tract and pancreas in rats.

Administration of pig calcitonin (10 M.R.C. units/kg body wt.) produced an immediate decrease in 5-hydroxytryptamine content in the antrum-duodenum region and ileum. In contrast, the hormone treatment rapidly increased the concentration of 5-hydroxytryptamine in the blood and pancreas. Serum immunoreactive gastrin did not change over a period of 3h after calcitonin administration. The results suggest that the release of 5-hydroxytryptamine probably mediates calcitonin actions on the gastrointestinal tract and pancreas.