AJP - Regulatory, Integrative and Comparative Physiology, Vol 268, Issue 6 1418-R1422, Copyright © 1995 by American Physiological Society
NPY increases food intake in white-crowned sparrows: effect in short and long photoperiods
R. D. Richardson, T. Boswell, B. D. Raffety, R. J. Seeley, J. C. Wingfield and S. C. Woods
Department of Psychology, University of Washington, Seattle 98195.
To determine if altered sensitivity to neuropeptide Y (NPY) underlies
premigratory fattening, white-crowned sparrows held on short day length
(9:15-h light-dark) received injections into the third ventricle (ivt) of
saline or several doses of NPY. An inverted-U function occurred with food
intake increasing 30 and 60 min after doses of 1.0 and 2.0 micrograms NPY.
When photostimulated (20:4-h light-dark), birds increased daily caloric
intake and gained weight rapidly. Birds maintained on long day lengths
significantly increased food intake after 0.25 and 0.5 micrograms of NPY
and did not respond to higher doses. The effective dose range for NPY to
increase food intake moved to the left, suggesting an increase in
sensitivity to the peptide on long day lengths. In summary, white-crowned
sparrows consume more food when administered NPY ivt and have increased
sensitivity when photostimulated and gaining weight. Hence NPY may be a
natural stimulator of food intake in this species.
