Effect of cysteamine on secretion of gastrin and somatostatin from the rat stomach.

Cysteamine (beta-mercaptoethylamine HCl) administration to rats induces a hypergastrinemia and a reduction in gastric tissue somatostatin content. The possibility that this reduction may contribute to the elevated gastrin levels has been investigated in the isolated perfused rat stomach. Cysteamine (1 mM) rapidly increased immunoreactive gastrin release to levels ranging between 41% and 125% above basal. Increasing the dose to 10 mM caused a 1148% increase in immunoreactive gastrin. Secretion of somatostatinlike immunoreactivity did not change. Perfusion of gastric inhibitory polypeptide (1 nM) induced a sustained increase in somatostatinlike immunoreactivity secretion and a transient rise in gastrin. Addition of 10 mM cysteamine during gastric inhibitory polypeptide perfusion caused a 300% increase in immunoreactive gastrin. These levels were lower than in response to cysteamine alone. The results demonstrate that cysteamine can stimulate immunoreactive gastrin secretion without any change in somatostatinlike immunoreactivity release. When somatostatinlike immunoreactivity secretion is stimulated by an agent such as gastric inhibitory polypeptide, the cysteamine-induced release of immunoreactive gastrin is attenuated, suggesting the presence of a functional linkage between somatostatin and gastrin under these conditions.