Acute blockade of gastric emptying and meal size in rats

To investigate the functional capacity of the combination of pregastric and gastric satiating stimuli for the control of meal size, rats were surgically implanted with a pyloric cuff that could be inflated to prevent gastric emptying. After 0.5 or 19 h of food deprivation, rats were given access for 30 min to three concentrations of sucrose (0.8, 0.4, and 0.2 M) and of corn oil emulsions (100%, 50%, and 25%) in descending order. There were only two significant changes in intake between cuff-open and cuff-closed tests and both occurred after 19 h of food deprivation: 1) meal size of 50% corn oil with the cuff closed was significantly larger than meal size of 50% corn oil with the cuff open on the preceding day; 2) meal size of 0.8 M sucrose with the cuff closed was significantly larger than meal size with the cuff open on the next test day. These results provide new experimental evidence that when ingested food is prevented from emptying from the stomach acutely, the satiating effect of food stimuli acting at pregastric and gastric sites is sufficient to produce meals of normal size under many, but not all, experimental conditions.