ABSTRACT
The brain stem contains receptors for insulin and other neuropeptides involved in the control of feeding. In the animals, neural mechanisms in the brain stem are disconnected from the circuits in the cerebral hemispheres that normally control them. Endocrine cells in the wall of the stomach and the small intestine are known to secrete peptides in response to food. These peptides include cholecystokinin (CCK), insulin and bombesin, although there are many others. These peptides have both peripheral and central actions producing satiety. Peripheral injection of CCK into rats and humans causes them to stop eating. W. B. Cannon and A. L. Washburn proposed the first notable theory of hunger. They recorded movements of the stomach by swallowing a balloon, inflating it, and connecting it to a recording device. It has long been known that the stomach can provide a satiety signal, since injection of food directly into the stomach of hungry experimental animals stops them eating.
