Effect of cephalic-vagal stimulation on insulin, gastric inhibitory polypeptide, and pancreatic polypeptide release in humans.

The purpose of the present study was to determine whether there is a cephalic phase of insulin or gastric inhibitory polypeptide release in man. Seven healthy, normal weight volunteers were sham fed an appetizing steak meal, and serum insulin, gastric inhibitory polypeptide, and pancreatic polypeptide concentrations were measured. A pancreatic polypeptide response to sham feeding was employed as marker of adequate cephalic-vagal stimulation. Although serum pancreatic polypeptide concentrations increased significantly (P less than 0.05) in response to sham feeding, sham feeding had no significant effect on serum insulin and gastric inhibitory polypeptide levels. In addition, sham feeding did not affect insulin or gastric inhibitory polypeptide responses to intragastric glucose, although sham feeding did augment the pancreatic polypeptide response to this meal. These experiments were, therefore, unable to demonstrate insulin or gastric inhibitory polypeptide release in response to cephalic-vagal stimulation in humans.