The effects of the C-terminal tetrapeptide of
gastrin,
tetragastrin, on the colonic mucosa on Days 15 and 25 during intrarectal administration of
N-methyl-N'-nitro-N-nitrosoguanidine (
MNNG) and its effects on the incidences of colonic
tumors in experimental Wk 20 and 35 were investigated in Wistar rats. Administration of
tetragastrin in depot form during instillation of
MNNG resulted in significant decreases in the incidences of mucosal erosions, ulcerations, and atypical regenerative glandular
hyperplasias in the colonic mucosa, most of these lesions being greater in the distal half of the colon. Administration of
tetragastrin also significantly decreased the incidences and/or numbers of colonic
tumors in Wk 20 and 35. The distribution of colonic
tumors induced in Wk 20 and 35 corresponded well to those of erosions, ulcerations, and atypical regenerative glandular
hyperplasias induced during the administration of
MNNG. These findings suggest that the effect of
tetragastrin in decreasing the incidences of erosions, ulcerations, and atypical regenerative glandular
hyperplasias in the colonic mucosa during instillation of
MNNG is related to its effect in reducing the development of colonic
tumors.