interactions of cholecystokinin COOH-terminal octapeptide (CCK-8) and somatostatin-14 (SS-14) on food intake in dogs were examined by administration of graded doses of these peptides alone and in combination. In animals fasted 19 h, SS-14 (2,000 or 20,000 pmol.kg-1.h-1) had no effect on food intake. In animals fasted 4 h, food intake was not affected by 40 or 400 pmol.kg-1.h-1 SS-14 but was significantly (P less than 0.05) increased by 20% after 4,000 pmol.kg-1.h-1 SS-14. Feeding responses to simultaneous infusions of CCK-8 (50 or 400 pmol.kg-1.h-1) and SS-14 (40, 400, or 4,000 pmol.kg-1.h-1) were determined in animals fasted 4 h. Given alone, the high dose of CCK-8 (400 pmol.kg-1.h-1) significantly (P less than 0.01) depressed food intake by 55%. This effect was blocked by all doses of SS-14. In the absence of CCK-8, SS-14 had no effect except at the highest dose (4,000 pmol.kg-1.h-1), which significantly (P less than 0.01) stimulated food intake by 57%. This effect was blocked by both doses of CCK-8. Simultaneous infusion of lower doses of SS-14 (40 and 400 pmol.kg-1.h-1) and CCK-8 (50 pmol.kg-1.h-1) had no effect on food intake. These results suggest that plasma levels of CCK and SS-14 after a meal are not sufficient alone or in combination to produce satiety.