GASTRIN REGULATES HISTIDINE-DECARBOXYLASE ACTIVITY AND MESSENGER-RNA ABUNDANCE IN RAT OXYNTIC MUCOSA

Gastrin releases histamine from the oxyntic mucosa, stimulates the enz ymatic activity of histidine decarboxylase (HDC), increases HDC mRNA a bundance, and has a trophic effect on the enterochromaffin-like (ECL) cell. In the present study, we examined the effect of exogenous gastri n on HDC activity and mRNA and the time scale of increase and decline of HDC activity and mRNA. Rats received intravenous infusion of gastri n-(1-17) in different doses or periods of time. Oxyntic mucosal HDC ac tivity and mRNA abundance increased significantly with serum gastrin c oncentrations in the physiological range. The onset of response was ra pid and maximal for both parameters after 2 h. Poststimulatory decreas e was maximal 2 h after cessation of gastrin infusion. Those observati ons suggest that HDC enzymatic activity and mRNA abundance are importa nt in meal-to-meal regulation of gastric secretion. Furthermore, HDC e nzymatic activity and mRNA abundance varied in parallel, indicating th at KDC mRNA abundance is important in the overall regulation of gastri c mucosal KDC activity.