Metabolic and physiologic effects of a hunger-inducing injection of insulin

Rats injected subcutaneously with 5 U/kg of regular insulin increased food intake above control levels in a 2 hr test and showed a median latency to eat of 59 min. One week later, rats were injected again with saline or insulin (5 U/kg), deprived of food and killed 60 +/- 10 min later. Insulin treatment produced a marked reduction in plasma glucose, plasma ketone bodies and liver glycogen, as well as a marked acceleration of gastric emptying. The results indicate that a variety of changes in peripheral metabolism and physiology may underlie the increase in food intake observed after insulin injection and that it is premature to ascribe the hunger-inducing effect of insulin treatment solely to a decline in blood glucose.