[Interaction between gastrointestinal hormones and endocrine regulation].

The vicinity of several hormone-producing glands as part of the anatomy of the intestinal tract and the resulting interaction has been confirmed by the discovery of hormonal factors of a specifically gastro-intestinal origin. Today we are mainly interested in the interaction between intermediary metabolism and incretory intestinal function; this is characterized by the joint action of conventional glandular hormones such as insulin and pancreatic glucagon as well as by the incretion of diffuse intestinal organs, hormones such as secretin, pancreozymin, motilin, VIP and GIP. The latter are at present subject of active research with the object of discovering their physiological significance be it as tissue hormones or as humoral agents with a "long distance" impact; their role within pathophysiology is also of interest. GIP ("gastric inhibitory peptide"), apart form acting upon the intestinal tract, also causes a marked rise in insulin production; this GIP possibly is the factor responsible for the difference in glucose tolerance following i. v. or oral administration of glucose, something that scientists have been trying to discover for a long time. We have also endeavored to investigate somatostatin. This substance was originally discovered as a hypothalamic factor with inhibitory action on growth hormone secretion; in the meantime, however, cells containing and possibly also producing somatostatin have also been detected in the intestine and particularly in the islets of Langerhans (D-cells). Since somatostatin inhibits insulin secretion and especially glucagon release as well as the exretory functions of the stomach and of the pancreas, the significance of this hormone possibly is that of a tissue hormone with inhibitory action on adjacent cells. As factor inhibiting both endocrine and exocrine secretory processes it would combine these two complexes. The possible therapeutic significance of somatostatin administration to diabetics would lie in the saving of insulin. A third sector of present-day research deals with the interaction between the calcium metabolism and the hormones involved as well as the intestine. We know that patients suffering from primary hyperparathyroidism are prone to contract stomach ulcers and pancreatitis; patients with a gastrinoma and a hyperfunction of the epithelial bodies suffer from a Zollinger-Ellison-sindrome and this again suggests association with endocrine polyadenomatosis (Wermer syndrome). The inhibitory action of the parathormone antagonist calcitonin on the exocrine functions of the intestinal tract, such as the acid secretion of the stomach and the enzyme secretion of the pancreas, have already given rise to some considerations and experiments relative to treatment. It is to be hoped that because of all the joint observations cited above there will be better intergration of research both from the aspect of gastro-enterology and endocrinology. This might hopefully elucidate some of the unresolved problems ranging from basic research to practical application.