SUPPRESSION OF MEAL SIZE BY INTESTINAL NUTRIENTS IS ELIMINATED BY CELIAC VAGAL DEAFFERENTATION

The arrival of nutrients in the gastrointestinal tract suppresses inta ke. To specify the neural pathways and receptor locations of this feed back, we examined the effects of intraduodenal infusions of 10 nutrien ts plus saline on short-term food intake of rats with selective deaffe rentations of vagal celiac branches. Three response profiles were obse rved: 1) isotonic saline, 5.6% glycerol, and 3% fructose did not inhib it intake of controls or selectively deafferented animals; 2) 3% gluco se, 3% maltose, 3% L-phenylalanine, 12% Isocal, and 1.4% oleic acid su ppressed intake of controls, but this inhibition was eliminated by vag al celiac deafferentation; and 3) 3% casein hydrolysate and 24% Isocal suppressed intake of controls and rats with selective vagotomies, alt hough the latter exhibited significantly less suppression. In addition , elimination of celiac afferents chronically reduced meal size (i.e., first 30-min intake) without reducing daily food intake or body weigh t. Furthermore, D-phenylalanine infusions produced a delayed suppressi on of food intake in controls (possibly from intraluminal irritation); however, this reduction was eliminated with celiac deafferentation. O verall, this experiment indicates that vagal celiac afferents are crit ical for preabsorptive detection of some energy-yielding molecules or properties of nutrient solutions (as well as, perhaps, intraluminal in flammation), but not others, which are still detected, although only p artially.