Control of food intake during continuous injection of glucose into the upper duodenum and the upper ileum of rats

Abstract

Duodenal factors have been implicated to participate in the elicitation of satiety during a single meal. This report evaluates the possible involvement of the upper small intestines in the day-to-day control of food intake. Glucose solutions, contributing about a third of the daily caloric intake of rats, were continuously injected into the gastrointestinal tract through a permanent catheter. The catheter was inserted into each animal at one of two locations: the upper duodenum and the upper ileum. There were five animals in each catheter group. Voluntary food intake was measured before and during glucose injection. Control injections of oil equicaloric to glucose and NaCl equiosmotic to glucose were also performed. All glucose injections resulted in a reduction in voluntary food intake which began as early as the first day of injection and compensated for most of the caloric content of the injected glucose. The reduction was similar for the two catheter groups. Equicaloric injections of oil produced an effect similar to glucose, while equiosmotic NaCl injections did not. It is concluded that if there is an intestinal metering system which participates in day-to-day control of food intake, it is not exclusively located in the upper small intestines.