EFFECT OF THE HISTAMINE-2 AGONIST IMPROMIDINE ON STEM-CELL PROLIFERATION OF RAT OXYNTIC MUCOSA

Background: The trophic effect of gastrin on the histamine-containing enterochromaffin-like cell is pronounced but on the stem cell of the oxyntic mucosa it is only modest. In the rat, gastrin stimulates acid secretion mainly by releasing histamine from enterochromaffin-like cells. This study was designed to test the hypothesis that the trophic effect of gastrin on stem cells is also mediated by histamine released from the enterochromaffin-like cell. Methods: We stimulated rats with the histamine-2 agonist impromidine. Impromidine, 0.2 mg/h, was given for 2 days by subcutaneously implanted osmotic minipumps, and the trophic effect on stem cells was assessed by incorporation of tritiated thymidine. Results: The plasma gastrin concentrations were 33.9 (9.4) pM and 27.3 (6.0) pM, and the stem cell labelling index values were 5.92 (1.94) and 8.09 (3.78) in the controls and impromidine-stimulated animals, respectively (mean value (SD)). These differences were not statistically significant. Conclusion: The present study provides no evidence that histamine-2 receptors mediate a trophic effect on the stem cell of the rat oxyntic mucosa.