Postgastric satiety in the sham-feeding rat

A sham-feeding model using rats fitted with gastric and duodenal cannulas was employed to investigate the role of postgastric mechanisms of satiety in the short-term control of food intake. When fasted rats sham fed a liquid diet [Vivonex High Nitrogen (VHN), 0.5 kcal/ml], food drained freely from gastric fistulas, and mean first-meal size and 90-min intake increased more than threefold. Varying the rate of duodenal infusion of diet during sham feeding (0.06-0.44 kcal/min) decreased first-meal size and total intake in a dose-dependent manner. First meals ended when mean loads of 2-3 kcal had been delivered. The threshold rate (0.11 kcal/min) decreased meal size and total intake by more than 50%. When fasted rats consumed VHN to satiety with closed gastric fistulas, rate of gastric emptying of diet during feeding averaged 0.32 +/- 0.02 kcal/min and the load emptied by meal termination averaged 3.8 +/- 0.2 kcal. These results indicate that rates of gastric emptying of diet and loads delivered to the small intestine following ingestion of liquid food are sufficient to elicit postgastric satiety in the absence of gastric distension.