EFFECT OF OCCLUDING THE PYLORUS ON INTRAORAL INTAKE - A TEST OF THE GASTRIC HYPOTHESIS OF MEAL TERMINATION

Meal size does not change in response to food being restricted to the stomach by occlusion of the pylorus. This result has been used as evidence for a gastric model of meal termination where feedback arising solely from the stomach is taken to underlie satiation. Such data provide support for the gastric model, however, only if the rate of gastric emptying during ingestion in the unoccluded condition is slow, such that comparable amounts of food would be found in the stomach at the end of the meal in both the pylorus-occluded and unoccluded conditions. To evaluate this issue directly, rats were implanted with pyloric cuffs and gastric cannulas and given an intraoral intake test of a 10.5% glucose solution with either the pylorus occluded or unoccluded. At the end of each intraoral intake test, the content of the stomach was removed via the gastric cannula and it's volume and concentration measured. Occlusion of the pylorus did not change meal size, but both the volume and grams of glucose solute found in the stomach were substantially greater in the pylorus-occluded condition. These results are not consistent with the hypothesis that the stomach is the sole source of inhibitory signals that terminate a meal. Cumulative intake would appear to be accurately tracked regardless of its distribution within the digestive tract.