There are now a large number of experiments demonstrating that peripheral administration of exogenous cholecystokinin or its synthetic analogue, CCK-8, reduces meal size in a number of species. The peptide interacts with other factors which influence satiety, and treatments thought to be effective in eliciting secretion of cholecystokinin have predictable effects on meal size. Cholecystokinin is effective in the genetically obese Zucker rat, obese rats with lesions of the ventromedial hypothalamus, and subdiaphragmatically vagotomized rats. Somatostatin and bombesin are also reasonable candidates for satiety factors. Intraperitoneal naloxone reduces meal size in rats, and beta-endorphin injected intraventricularly causes an increase in meal size of 50% over 30 minutes. We conclude that cholecystokinin and bombesin may interact in weight regulation and control of meal time food intake.
Keywords: CCK; Satiety; VIP; Zucker (Fatty) rats; beta-endorphin; bombesin; meal size; somatostatin; vagotomy.