Bombesin-like immunoreactivity in rat brain and gastrointestinal tract: influence of diet and starvation.

A radioimmunoassay has been developed for the measurement of bombesin-like immunoreactivity (BLI) in mammalian tissues. BLI has been demonstrated in large amounts in the rat stomach and colon and in smaller amounts in the rat central nervous system. A 7-day high-carbohydrate diet leads to an increase in gastric and colonic BLI, a high protein diet to a decrease in fundic BLI. High fat and protein diets led to a decrease in midbrain BLI but other nervous tissues were not influenced by variation in diet. A 6-day fast increased antral, jejunal and ileal BLI; these increased levels fell on refeeding. These studies suggest a role for endogenous BLI in some aspects of gastric physiology, perhaps gastrin release.