Gastric volume rather than nutrient content inhibits food
intake.
Phillips, Robert J., & Terry L. Powley.
Purdue University, West Lafayette, IN 47907
APStracts 3:0131R, 1996.
To evaluate the separate contributions of distension and nutrient
stimulation of the stomach to the inhibition of short term food
intake, and particularly to reassess previous analyses based on the
inflatable gastrointestinal cuff, four experiments were performed.
Rats equipped with pyloric cuffs and indwelling gastric catheters
consumed a liquid diet ad libitum. Their consumption during a short
term (30 min) feeding bout was measured after gastric infusions on
cuff-open and cuff-closed trials. Animals taking meals (approx. 5 ml)
with cuffs closed, immediately after receiving intragastric infusions
of 2.5, 5, 7.5, or 10 ml of normal saline, exhibited both suppression
at the smallest infusion and a dose-dependent reduction across the
other volumes (Experiment 1). Additionally, when the test diet
concentration was varied, animals with their cuffs closed consumed a
constant volume, not a constant number of calories (Experiment 2).
Furthermore, cuff-closed animals exhibited no more suppression to 5
ml intragastric infusions of nutrients (including, on different
trials, 50 and 100% Isocal diet, 10, 20 and 40% glucose, as well as
40% sucrose and 40% fructose) than to the same volume of saline
(Experiments 3 and 4). In contrast, on cuff-open trials in which
gastric contents could empty into the duodenum, these same nutrient
loads were more effective (except fructose) than saline in producing
suppression of food intake. In summary, although both limited gastric
distension with the pylorus occluded and intestinal nutrient
stimulation with the cuff open effectively reduced intake, cuff
-closed gastric loads of mixed macronutrients or carbohydrate
solutions of 2 to 8 kcal, of pH from 5.8 to 6.7, and of osmolarities
between 117 and 2,294 mosmols/kg produced only the distension-based
suppression generated by the same volume of saline.
Received 28 December 1995; accepted in final form 27 March 1996.
APS Manuscript Number R824-5.
Article publication pending Am. J. Physiol. (Regulatory Integrative
Comp. Physiology).
ISSN 1080-4757 Copyright 1996 The American Physiological Society.
Published in APStracts on 16 April 96