The effects of alimentary infusions of glucose, amino acids, or neutral fat on meal size in hungry pigs.

1. Young growing pigs trained to press a panel in order to obtain delivery of small quantities of food were adapted to eating all their food during one readily measured meal per day. 2. Twenty-nine pigs were surgically fitted with an exteriorized cannula connected to either (a) the stomach or (b) the duodenum. 3. Two pigs were each fitted with two cannulae in the duodenum which were exteriorized and connected outside the body. Food was then shunted so as to pass along outside the body from the pyloric region of the duodenum to the lower part of the duodenum via the tube connecting the exteriorized cannulae. 4. While feeding, the pigs were given 250 ml. infusions of solutions of (1) 0.9% saline or (2) 15% glucose into either the stomach or the duodenum. Similar volumes of amino acids or 15% neutral fat were infused into the duodenum. 5. The infusions lasted about 3 min and were started 2-3 min after the beginning of a meal. 6. Control meals without infusions took 30-40 min. The 15% intraduodenal glucose infusions consistently produced a suppression of eating 15-20 min after the end of the infusion. 7. Infusions of 0.9% saline, of 10% amino acid or of 15% neutral fat did not reduce significantly the intake of food or the duration of the meal. 8. It was not clear how the glucose solution was able to suppress appetite. The possible existence of a specific glucose receptor is discussed.