AJP - Regulatory, Integrative and Comparative Physiology, Vol 271, Issue 4 1009-R1016, Copyright © 1996 by American Physiological Society
Interpretation of sham feeding data: curve-shift studies
H. P. Weingarten, A. Duong and D. Elston
Department of Psychology, McMaster University, Hamilton, Ontario, Canada.
We explored the possibility that quantitative analysis of the relationship
between sucrose concentration and sham intake differentiated how various
treatments affected the intake of sweet solutions. Rats were sham fed
sucrose solutions varying in concentration from 0.03125 to 1.5 M. Under
different treatment conditions, intake concentration functions were
generated that plotted amount sham fed against sucrose concentration.
Sucrose concentration that yielded 50% maximal sham intake were calculated
to indicate the position of the concentration-intake function on the
x-axis. Quinine adulteration of sucrose solutions and injection of 0.5
mg/kg i.p. of the dopamine antagonist pimozide reduced sham intake and
shifted the concentration-intake function to the right. Lithium chloride
(60 mg/kg i.p.) injected 30 min before sham feeding, a reduction of food
deprivation from 18 to 6 h before sham feeding, and 6 micrograms/kg
cholecystokinin octapeptide reduced sham intake equivalent amounts but did
not shift the concentration-intake functions along the x-axis. The data
indicate that of several factors that reduce sham feeding, only some also
shift the position of concentration-intake curves, and these curve shifts
may identify intake changes mediated by alterations in the processing of
the taste input.
