Central nervous system action of bombesin to inhibit gastric acid secretion

Bombesin or gastrin releasing peptide injected into the lateral, third, or fourth ventricle, or into the cisterna magna, inhibited gastric acid secretion induced by a wide variety of gastric acid stimulants in several animal models. Studies of bombesin microinfusion into specific hypothalamic nuclei of intact rats, or injection into the cisterna magna of midbrain transected rats, indicated that the peptide can trigger inhibition of gastric acid secretion from both forebrain and hindbrain structures. The neural pathways mediating bombesin action required the integrity of the cervical spinal cord; the vagus did not play an important role. Spantide, a substance P and bombesin receptor antagonist, was not useful in studying the physiological role of bombesin. This was due both to its inability to reverse the central action of bombesin on gastric secretion, and to its in vivo toxicity.