Cholecystokinin-8 increases the satiety ratio in diabetic rats more than cholecystokinin-33.

Cholecystokinin (CCK) is a satiety peptide and a potential anti-diabetic agent, which exists in different forms (e.g. CCK-8 and CCK-33). In normal rats, CCK-8 and 33 stimulate insulin secretion similarly but their satiety effects vary. In diabetic rats, those effects require testing. Here, we compared size of the first meal (10% sucrose test diet), intermeal interval (IMI, time between first and second meal) and satiety ratio (SR, amount of satiation produced by every unit of food consumed in the first meal) by CCK-8 or 33 (0, 1, 3, 5nmol/kg) intraperitoneally in streptozotocin-injected (diabetic) and citrate buffer-injected (control) rats. We found that both peptides reduce meal size in diabetic and control rats with no difference between groups, CCK-33 (5nmol) prolonged IMI in diabetic rats and CCK-8 and CCK-33 increased satiety ratio in control rats, but only CCK-8 increased it in the diabetic group. Therefore, CCK-8 increases the satiety ratio in diabetic rats more than CCK-33.