Inhibitory effect of chloroform-resistant bacteria on polyposis in the small intestine of gnotobiote BALB/c mice

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The spontaneous polyposis in the small intestine of BALB/c gnotobiotic (GB) mice was studied. GB mice were derived from the germ-free (GF) mice by administering various strains of intestinal bacteria. Incidence of polyposis and the number of polyps per mouse were lower for CRB mice, and higher for groups of GB mice than for GF mice. This suggests that the polyposis was inhibited by the presence of the CRB in GB BALB/c mice.The influences of chemical carcinogens on spontaneous polyposis in the small intestine of germfree BALB/c mice was studied. N-methyl-N'-nitro-N-nitrosoguanidine (MNNG) in drinking water (100 mug/ml) was given to mice from 8 to 29 weeks of age (MNNG-Y group) and from 30 to 45 weeks of age (MNNG-A group) ad lib., and 1,2-Dimethylhydrazine dihydrochloride (DMH ; 20 mg/kg body weight) were administered intraperitonealy injection at weekly interval for 5 weeks from 8 weeks old (DMH-Y group) and 30 weeks old (DMH-A group), respectively, When the animals were 12 months old, … More they were killed and autopsied carefully for the number of polyps in the small intestine. The incidence of polyposis was significantly higher in all groups of treated with carcinogens than in non-treated control group. In histopathological examination, the polyp was not distinctly led to the malignancy by treating with different carcinogens. The present study suggested that number of polyps was enhanced by treating with carcinogens, while there was no evidence for the development of malignant polyps in the small intestine of germ free BALB/c mice.The spontaneous polyposis in the small intestine of BALB/c gnotobiotic (GB) mice associated with chloroform resistant bacteria (CRB), fusiform bacteria (FB) and segmented filamentous bacteria (SFB), respectively, was studied. Incidence of polyposis and the number of polyps per mouse were significantly lower for CRB and FB mice than for GF mice (p<<0.05), and those for SFB mice was not different from those of GF mice. This suggests that the polyposis was inhibited by the presence of the CRB or FB in GB BALB/c mice. significantly lower for CRB and FB mice than for CF mice (p<<0.05), and those for SEB mice was not different from those of GF mice. This suggests that the polyposis was inhibited by the presence of the CRB or FB in GB BALB/c mice. Less