Effect of naloxone on intake of cornstarch, sucrose and polycose
diets in restricted and non-restricted rats.
Weldon, Derik T., Eugene O'hare, James Cleary, Charles J. Billington,
Allen S. Levine.
Research Service, Department of Medicine and Geriatric Research,
Education and Clinical Center, VA Medical Center, Minneapolis, MN
55417; Departments of Food Science and Nutrition, Medicine,
Psychiatry, Psychology, Surgery and School of Public Health,
University of Minnesota, Minneapolis, MN 55455
APStracts 2:0353R, 1995.
We studied the effect of the opioid receptor antagonist naloxone on
intake of three isocaloric diets containing cornstarch, sucrose or
polycose as the predominant carbohydrate in ad libitum and food
restricted rats. A large body of evidence suggests that opioids
affect palatability (reward) rather than hunger (energy deficit)
driven food intake. We expected food intake to be driven by both
energy needs and palatability in ad libitum fed rats, whereas in food
restricted rats we expected intake to be driven by energy needs with
a relatively small palatability component in the preferred sucrose
and polycose diet groups. In the ad libitum fed rats, naloxone
significantly reduced nocturnal intake of all three diets at doses of
0.3, 1.0 and 3.0 mg/kg. In contrast, naloxone failed to alter intake
of the cornstarch diet in chronically food restricted rats. However,
naloxone decreased intake of the sucrose diet in food restricted rats
at doses of 0.3, 1.0 and 3.0 mg/kg and decreased intake of the
polycose diet at the 3 mg/kg dose. These data lend further support to
the notion that opioids are involved in some other component of
feeding than that induced by energy needs.
Received 20 March 1995; accepted in final form 11 December 1995.
APS Manuscript Number R184-5.
Article publication pending Am. J. Physiol. (Regulatory Integrative
Comp. Physiology).
ISSN 1080-4757 Copyright 1995 The American Physiological Society.
Published in APStracts on 23 December 95