Fig. 1.

In ad libitum-fed male rats (n = 11) responding on a progressive ratio (PR) schedule of reinforcement, intragastric (IG) sucrose infusion (15 kcal) significantly reduced (A) active lever presses, (B) breakpoint, and (C) number of reinforcers earned. D: IG sucrose significantly suppressed overnight chow intake. Data for A–C are means ± SE of two replicate experiments, whereas chow intake data for D is from the second replicate alone. PR data were analyzed using repeated-measures two-way ANOVA (IG nutrient × replication), and chow intake from the second repetition was analyzed using paired-samples t-test. *P < 0.05 relative to saline.