Neurobiologic and psychobiologic mechanisms in gastric function and ulceration.

The initiation and termination of feeding behavior are not fully understood. The stomach has been implicated as one source of signals regulating food intake. The sight and smell of food are potent stimuli to gastric acid secretion and contraction. The mouth, upper gastrointestinal tract and liver contain receptors regulating food intake; afferent information passes into the brain stem and into the brain areas. Lateral hypothalamic lesions abolish feeding, raise the body temperature and basal gastric acid secretion and produce gastric erosions. Vagotomy and administering propantheline bromide abolish the increased acid secretion after such lesions; they also alter the mucosal barrier permitting diffusion of protons into mucosal cells. Several of the neuropeptides via the central nervous system stimulate or inhibit gastric acid secretion through modulation of the autonomic nervous system. Most animal models of gastric erosions are associated with a reduced body temperature. Unknown is whether or not this association is the result of increased levels of thyrotropin-releasing hormone-a potent stimulus to gastric acid secretion and erosion formation when injected intracisternally.