Rationale: Feeding consists of appetitive or foraging behavior followed by consummatory behavior.
Objectives: To determine if pharmacological manipulations can differentially affect appetitive and consummatory aspects of food intake, and to compare these results to those obtained using naturalistic dietary manipulations.
Methods: Responding of baboons was studied using a schedule of reinforcement that simulated food "seeking" and food "taking." Responding during the seeking component was reinforced by stimuli paired with food, while responding during the taking component was reinforced with food. The effects of intramuscular amphetamine (AMPH), dexfenfluramine (DFEN), diethylpropion (DEP), phencyclidine (PCP), diazepam (DZP), as well as caloric prefeeding and acute food deprivation were determined.
Results: AMPH decreased food taking and increased food seeking, DEP decreased food taking without affecting food seeking, DFEN and PCP decreased both food taking and food seeking, while DZP increased both food taking and food seeking. Caloric prefeeding decreased food taking and increased food seeking, i.e., resembled AMPH, while acute deprivation increased both food taking and food seeking, i.e., resembled DZP.
Conclusions: Manipulations that increase dopamine turnover, such as AMPH, increase food seeking, while decreasing food intake. In contrast, manipulations that increase serotonin turnover, such as DFEN, decrease both food seeking and food taking.