AJP - Regulatory, Integrative and Comparative Physiology, Vol 256, Issue 1 56-R62, Copyright © 1989 by American Physiological Society
Gastric emptying changes are neither necessary nor sufficient for CCK-induced satiety
K. L. Conover, S. M. Collins and H. P. Weingarten
Department of Psychology, McMaster University, Hamilton, Ontario, Canada.
If gastric emptying plays a significant role in the satiety produced by
exogenous cholecystokinin octapeptide (CCK-8) then 1) the effects on
emptying and feeding should share similar kinetics and 2) peptides that
inhibit emptying should also inhibit feeding. In the first experiment,
CCK-8 (5.6 micrograms/kg) injected immediately before the introduction of
an intragastric load (10 ml saline) or presentation of a test meal (15%
sucrose) produced a rapid inhibition of both emptying and feeding. In
contrast, the same dose administered 15 min before testing caused no
inhibition of emptying, even though it retained the ability to reduce meal
size. In experiment 2, the abilities of the peptides pentagastrin (100
micrograms/kg), bombesin (8 and 16 micrograms/kg), and secretin (2.86,
14.3, and 28.6 micrograms/kg) to reduce food intake and inhibit emptying
were tested. Pentagastrin influenced neither food intake nor gastric
emptying. Bombesin caused a small transient delay in emptying but a large
and sustained eating suppression. However, a high dose of secretin caused
no significant reduction of food intake, in spite of the fact that it
inhibited emptying to the same degree as 1.4 micrograms/kg CCK-8, which
does reduce intake. These results suggest that the inhibition of emptying
by CCK is not sufficient to explain the satiety effect of CCK-8.
