CCK-8 induced inhibition of food intake is mediated through the CCK-A receptor. After an overnight fast, animals were injected with either saline or CCK-8 and provided access to chocolate-flavored Ensure as described in Methods. Cumulative intake (mean ± SEM) over a 15-min period after injection is shown. Significance vs. intake after saline injection (0 μg CCK-8/kg body weight [BW]): *P < 0.05, **P < 0.01. (a) CCK-8 induced, dose-dependent inhibition of food intake is observed in wild-type (WT), but not in CCK-AR^–/– mice. Food consumption by 10 wild-type and 10 CCK-AR^–/– animals was compared. ANOVA parameters were [F(3,39) = 89.23, P < 0.0001] and [F(3,39 )= 0.16, P = 0.92] for comparisons among wild-type and CCK-AR^–/– animals, respectively. (b). CCK-8 induced, dose-dependent inhibition of food intake is observed in both wild-type and CCK-BR^–/– mice. Food consumption by 9 wild-type and 10 CCK-BR^–/– animals was compared. ANOVA parameters were [F(3,35) = 44.40, P < 0.0001] and [F(3,39) = 135.21, P < 0.0001] for comparisons among wild-type and CCK-BR^–/– animals, respectively. BW, body weight.