INTERPRETATION OF SHAM-FEEDING DATA - CURVE-SHIFT STUDIES

We explored the possibility that quantitative analysis of the relation ship between sucrose concentration and sham intake differentiated how various treatments affected the intake of sweet solutions. Rats were s ham fed sucrose solutions varying in concentration from 0.03125 to 1.5 M. Under different treatment conditions, intake-concentration functio ns were generated that plotted amount sham fed against sucrose concent ration. Sucrose concentrations that yielded 50% maximal sham intake we re calculated to indicate the position of the concentration-intake fun ction on the x-axis. Quinine adulteration of sucrose solutions and inj ection of 0.5 mg/kg ip of the dopamine antagonist pimozide reduced sha m intake and shifted the concentration-intake function to the right. L ithium chloride (60 mg/kg ip) injected 30 min before sham feeding, a r eduction of food deprivation from 18 to 6 h before sham feeding, and 6 mu g/kg cholecystokinin octapeptide reduced sham intake equivalent am ounts but did not shift the concentration-intake functions along the x -axis. The data indicate that of several factors that reduce sham feed ing, only some also shift the position of concentration-intake curves, and these curve shifts may identify intake changes mediated by altera tions in the processing of the taste input.