AJP - Regulatory, Integrative and Comparative Physiology, Vol 259, Issue 4 823-R828, Copyright © 1990 by American Physiological Society
Insulin modifies flavor aversions and preferences in real- and sham-feeding rats
D. A. Vanderweele, R. O. Deems and R. B. Kanarek
Department of Psychology, Occidental College, Los Angeles, California 90041.
In separate, parallel experiments, rats were allowed to sham or real feed a
flavored sweetened condensed-milk solution after a 17.5-h fast. Coinciding
with administration of the milk were injections of insulin or vehicle
(saline). Insulin had no effect on intake in the real feeding situation,
and flavors paired with insulin (0.8, 2.5, or 5.0 U/rat) were avoided,
relative to saline-paired flavors. In sham-feeding rats, insulin (0.8
U/rat) significantly reduced the amount of milk consumed, and flavors
paired with insulin injection were preferred, relative to saline-paired
ones. Insulin produced a relatively larger hypoglycemia during sham feeding
than during real feeding. Thus it appears that insulin-paired flavors of
milk may be preferred by animals when they are ingested in sham feeding but
not in animals real feeding. Perhaps rapid gastric emptying, as would occur
with a liquid diet, accompanied by increased insulin levels, leads to
malaise and flavor aversion.
