Gastric emptying of ingested fat emulsion in rats: implications for
studies of fat-induced satiety.
Friedman, Mark I., Israel Ramirez, and Michael G. Tordoff.
Monell Chemical Senses Center, Philadelphia, PA
APStracts 3:0014R, 1996.
Evidence that ingested fat acts in the intestine to produce satiety
stems from studies showing that intraintestinal infusion of fat
emulsion inhibits eating behavior of rats. In this study, we
determined the appropriateness of infusion parameters used in these
behavioral studies by measuring gastric emptying rates of both the
aqueous and lipid components of Intralipid ingested normally by rats.
Stomach contents were collected at different times 0-40 min after
rats ingested Intralipid containing 14C-polyethylene glycol (PEG) and
phenol red (PR), and were assayed for PEG, PR and fat. The proportion
of ingested fat remaining in the stomach was significantly greater
than the proportion of ingested PEG or PR at all time points
examined. Despite initial gastric emptying of fat during ingestion,
consumption of Intralipid (0.5 or 1.1 kcal/ml) did not suppress
subsequent solid food intake. The results indicate that (i) ingested
fat emulsion rapidly partitions in the rat stomach into an aqueous
phase, which empties rapidly, and a lipid phase, which empties
slowly, and (ii) normal ingestion of Intralipid is not immediately
satiating. These observations questions about the physiological
significance of the rapid and marked suppression of feeding behavior
produced by intraintestinal infusion of Intralipid.
Received 19 September 1995; accepted in final form 18 December
1995.
APS Manuscript Number R586-5.
Article publication pending Am. J. Physiol. (Regulatory Integrative
Comp. Physiology).
ISSN 1080-4757 Copyright 1996 The American Physiological Society.
Published in APStracts on 22 January 96