CONTROL OF GASTRIC CORPUS CHROMOGRANIN-A MESSENGER-RNA ABUNDANCE IN THE RAT

Enterochromaffin-like cells in the corpus mucosa of the stomach produce histamine in response to gastrin; chromogranin A (CGA) is often used as a morphological marker for these cells, but its functional significance in the gastric mucosa is largely unknown. We have examined whether CGA mRNA abundance in the rat corpus is controlled by endogenous gastrin. In rats fasted for up to 48 h, there was a progressive decline in plasma gastrin and CGA mRNA; refeeding of fasted rats produced a prompt increase in plasma gastrin and an increase in CGA mRNA that was significant after 4 h. Treatment of fasted rats with omeprazole to inhibit acid secretion increased plasma gastrin and CGA mRNA levels. The increased CGA mRNA associated with omeprazole or refeeding was reversed by treatment of rats with the gastrin/cholecystokinin B antagonist CI-988 and gastrin antibody, respectively. The results suggest that CGA production in enterochromaffin-like cells of the rat stomach is part of the functional response of these cells to circulating gastrin.