Hyperinsulinemia and its role in maintaining the hypothalamic hyperphagia in chickens

Electrolytic lesions of the ventromedial hypothalamus including nucl. hypothalamicus inferior caused the cockerels to become hyperphagic. The plasma insulin level of the control birds was low before feeding and it increased after feeding, while that of the hyperphagic birds was higher before feeding and increased even more after feeding. Under the fasting condition on the 19th day, the insulin secretion of the hyperphagic birds remained at a high level, and there was a high correlation between the insulin value and the food consumption. Hyperactivity of insulin secretion in the hypothalamic hyperphagic birds was inhibited by administration of diazoxide and their insulin levels declined to a level similar to that of the controls. As a result the hyperphagia was interrupted and the daily food consumption declined to the same level as the controls. Therefore, the hyperinsulinemia seemed to be necessary for maintaining the hypothalamic hyperphagia in chickens. The role of glucagon in this phenomenon is also discussed.