Several doses of the C-terminal tetrapeptide fragment of cholecystokinin octapeptide (CCK-5-8) were injected intraperitoneally (ip.) and intracerebroventricularly (icv.), and their effects on the feeding of 24-hr food-deprived rats in familiar and novel environments were studied. In the familiar environment, CCK-5-8 ip. or icv. had no effect on the food intake of the rats. In the novel environment (i.e. in an open field), CCK-5-8 showed merely slight effects on the main open-field parameters: only ip. administered CCK-5-8 enhanced the incidence of grooming. Of the feeding parameters tested in the open field, mainly the food intake/approach to food ratio was depressed by CCK-5-8 ip. or icv. The 24 μmole/kg ip. dose of CCK-5-8 decreased the food intake, while the 8 pmole icv. dose increased the number of approaches to food. After the treatments found to be the most effective, the latency to first bite was also enhanced. The results suggest that CCK-5-8 can amplify the arousal enhancement elicited by novelty through a central mechanism.
ASJC Scopus subject areas
- Endocrine and Autonomic Systems
- Cellular and Molecular Neuroscience