Cholecystokinin octapeptide (CCK-8) and glucagon (GLG) decrease food intake of a number of species. However, the responsiveness of rats to the food intake effects of these peptides may develop differentially due to sex, age and/or developmental state. Male and female weanling rats decreased early dark cycle food intake following the administration of 5 and 10 μg/kg CCK-8 and male rats were more responsive than female rats, p<0.05. GLG did not decrease early dark cycle food intake of either male or female weanling rats. Weanling male rats increased plasma glucose and insulin levels in response to GLG administration, p<0.05. Male rats were retested with GLG (250 and 500 μg/kg) at 6, 9 and 22 weeks of age. GLG did not decrease food intake of these rats until they reached 9 weeks of age and they were still responsive at 22 weeks of age, p<0.05.
- Food intake
- Plasma insulin