Regulation of food intake by metabolic fuels in white-crowned
sparrows.
Boswell, Timothy, Ralph D. Richardson, Randy J. Seeley, Marilyn
Ramenofsky, John C. Wingfield, Mark I. Friedman, and Stephen C.
Woods.
Departments of Zoology and Psychology, University of Washington,
Seattle, WA 98195, and Monell Chemical Senses Center3, Philadelphia,
PA 19104
APStracts 2:0188R, 1995.
Migratory birds rely on increased fat storage and fatty acid
utilization to meet seasonal changes of energy expenditure and as a
result increase food intake and fat stores before migration. To
determine whether their feeding behavior is sensitive to carbohydrate
and/or fatty acid utilization, white-crowned sparrows maintained on
short daylength (9L15D) were injected IP with 2-deoxy-D-glucose (2
-DG) or 2,5-anhydro-D-mannitol (2,5-AM). Low doses of 2-DG (25 or 50
mg/kg) had no effect on food intake and higher doses (100 or 300
mg/kg) significantly suppressed feeding after 1 and 2 hours. No dose
of 2-DG increased meal size. Similarly, low doses of 2,5-AM (25, 50
or 100 mg/kg) had no effect on food intake, and higher doses (300 and
600 mg/kg) significantly suppressed intake. These data suggest that
decreased carbohydrate metabolism does not elicit feeding in this
species. Importantly, these drugs, as well as insulin and glucagon,
were demonstrated to increase plasma fatty acids as well as to
decrease feeding. Injections of tributyrin (100, 300, 600 or 2000
mg/kg IP) or glycerol (300, 450 and 600 mg/kg) also significantly
suppressed 60-min and 120-min food intake dose-dependently in these
birds, and equimolar glucose (1200 mg/kg) had no effect. We conclude
that feeding by the white-crowned sparrow is unresponsive to
manipulations of carbohydrate metabolism, and is decreased following
manipulations that increase plasma lipids.
Received 24 March 1995; accepted in final form 27 June 1995.
APS Manuscript Number R200-5.
Article publication pending Am. J. Physiol. (Regulatory Integrative
Comp. Physiology).
ISSN 1080-4757 Copyright 1995 The American Physiological Society.
Published in APStracts on 18 July 1995.