BOMBESIN INHIBITS HISTAMINE-RELEASE FROM THE RAT OXYNTIC MUCOSA BY A SOMATOSTATIN-DEPENDENT MECHANISM

Background and methods: This study examines the effect of bombesin on endogenous somatostatin and the histamine-synthesizing enterochromaffi n-like cells. Somatostatin and histamine were measured in the venous e ffluent of isolated/antrectomized vascularly perfused rat stomachs aft er administration of bombesin and gastrin alone or combined. Histidine decarboxylase (HDC) enzyme activity and mRNA abundance were measured in the gastric corpus after intravenous administration of bombesin to conscious rats. Results: Bombesin released somatostatin from the isola ted stomachs and reduced basal and gastrin-stimulated venous histamine . Somatostatin antiserum partially reversed the effect of bombesin on basal and gastrin-stimulated histamine release. In conscious fed rats, intravenous bombesin doubled serum gastrin concentrations and increas ed HDC activity. Conclusion: We conclude that endogenous (paracrine) s omatostatin inhibits basal and gastrin-stimulated histamine release fr om the ECL cell. In intact animals this effect is surmountable by simu ltaneously released gastrin, suggesting that a balance,between the eff ects of gastrin and somatostatin determines the activation of the ECL cell.