Diurnal variations of cephalic exocrine pancreatic response in dogs

The purpose of this study was to determine effects of oral stimulation of sucrose on the diurnal output of pancreatic secretion in conscious dogs. Male beagle dogs weighing 9-11 kg were prepared with gastric and duodenal fistulae. Once a day at 14:00 the animals were trained to eat a sufficient amount of a commercial stock diet to maintain their body weight. Gustatory receptors were stimulated at 9:00, 13:00, 15:00, and 18:00 for 5 min with 100 ml of 0.5% agar solutions containing 0.3 M sucrose. Pancreatic juice was collected every 5 min before and after stimulation, and volume flow and protein output were measured. As a result, we demonstrated daily fluctuations timed by feeding not only in the pancreatic basal secretions but also in pancreatic responses to the gustatory stimulation. These results suggest the significant role of taste stimuli in the nutrition of, at least digestion in, animals.