Promoting effect of sodium deoxycholate on colon adenocarcinomas in germfree rats

The promoting effect of sodium deoxycholate (DC) on colon carcinogenesis was studied in female F344 germfree rats. Animals received intrarectal (ir) instillations of N-methyl-N'-nitro-N-nitrosoguanidine (MNNG) for 4 weeks (total dose, 16 mg/rat), then weekly ir doses of DC (total dose, 3 g/rat); the rats were autopsied 52 weeks after the first injection. DC increased the number of MNNG-induced colon adenocarcinomas. No tumors were in the colons of germfree rats given DC alone. It was concluded that DC (present in high concentrations in human stools) had a promoting effect on colon carcinogenesis in rats.