Effects of Helicobacter pylori and bile on N-methyl-N '-nitro-N '-nitrosoguanidine exposed antral mucosa of C57BL/6 mice

The aim of this study was to evaluate the early influence of Helicobacter p ylori infection on cell kinetics in the antral mucosa of mice exposed to N- methyl-N ' -nitro-N ' -nitrosoguanidine (MNNG) and bile alone or in combina tions. Four hundred and one C57BL/6 male and female mice were assigned into seven treatment groups and one non-treated control group. The gastric antr ums were assessed by histology and immunohistochemistry for studies of cell proliferation and apoptosis at 32 and 44 weeks. One female and one male mo use had developed dysplastic adenomas in the pylorus mucosa and one male an imal had dysplastic proliferation in the antrum. Only one of these lesions occurred in a H. pylori colonized animal. H. pylori infection significantly increased the cell proliferation at 32 weeks and promoted the cell prolife ration in the MNNG and bile group at 44 weeks. Female mice showed less incr ease in cell proliferation than did the males. No change in apoptosis was s een in any of the groups. Bile had no promotional effect on cell proliferat ion. These results indicate that H. pylori infection has the potential to a lter epithelial cell kinetics as well as antrum mucosa of an animal species that is regarded as resistant to MNNG. However, this change is not suffici ent to promote the early development of neoplastic lesions.