The mechanism of insulin secretion after oral glucose administration

Summary Previous experiments have shown that in an oral glucose tolerance test insulin is mobilized in the first phase independent of the following hyperglycemia. By giving different amounts of glucose (0.5–2.0 g/kg) in conscious trained dogs it was shown that this early phase of insulin secretion was stimulated independently of the administered glucose load by additional mechanisms. These mechanisms, at least partly, were triggered in the nerve endings of the cavity of mouth: their paralysis by mucosal anaesthesia abolished the early IRI-increase in intact animals as well as after feeding glucose to dogs bearing oesophagus fistulas. Spraying sodium cyclamate into the mouth did not produce any IRI-increase. The results indicate that the taste modality sweet is not involved in this reflex response. Conditioned reflexes as a consequence of the training programme or of the daily feeding regime were excluded by control experiments.The authors are grateful to Mrs. Karla Brüllke, Mrs. Helga Schröder, Miss Gisela Schmidt and Miss Helga Schüler for careful technical assistance.