The effect of isotonic glucose on eating as a function of feeding condition and infusion site

Rabbits were infused with 10 cc of 5% glucose and equal volumes of isotonic saline in a free-feeding condition and following a 22-hr total food-deprivation period. Infusions were made into the duodenum or a collecting vein of the hepatic-portal system through chronic indwelling cannulas. The results showed that duodenal infusions of glucose suppressed feeding only in the free-feeding rabbit while hepatic-portal infusions suppressed feeding only in the food-deprived animal. Both suppressive effects of isotonic glucose were eliminated by bilateral, subdiaphragmatic vagotomy. The results suggest that at least two loci can act to reduce eating following glucose intake and the locus of the effect is dependent upon the feeding condition or nutritional state of the animal.