Influence of caloric intake on gastric inhibitory polypeptide, VIP and gastrin release in man

Blood glucose, gastric inhibitory polypeptide (GIP), vasoactive intestinal polypeptide (VIP) and gastrin secretions were measured over a three-hour period following the ingestion by normal subjects of a mixed meal with two different caloric levels (1055 Kcal and 1192 Kcal). No VIP secretion was observed after either meal. Gastrin release was not modified by the increase of caloric intake (mainly carbohydrates and lipids), whereas GIP secretion was significantly more important after the meal with the highest caloric value (peak at 30 mm: 499.5 +/- 250.4 vs. 273.4 +/- 128.7 pg/ml and integrated response 53.3 +/- 20.5 vs. 28.2 +/- 9.9 ng X ml-1 X 180 min-1-p less than 0.05). This difference could not be attributed to glucose since the blood glucose levels were not significantly different. It is more probably related to the total amount of ingested food. This suggests the existence of rapid mechanisms of adaptation to the incoming load of the GIP-producing cells.