Adenocarcinoma production in rats administered 1,2-dimethylhydrazine and fed iron salt and guar gum diets

Iron salts supplemented in a basal ratio, were fed to young Sprague-Dawley male rats for prolonged periods and the frequency of colonic adenocarcinomas induced by repeated s.c. injection of 1,2-dimethylhydrazine (DMH) at unit base doses of 9.0 mg/kg, ascertained and compared with the respective controls. In a series employing ferric ammonium citrate (0.46% Fe), in addition to ferrous sulfate (0.11% Fe) and ferric ammonium sulfate (0.12% Fe), DMH injection was started on day 15 and the animals necropsied 22 weeks after the last of 23 doses. The general condition was more involved with the 0.46% Fe diet and the total colonic lesion numbers were in the control range. However, the ferric ammonium sulfate-fed group showed a significant increase in tumors in the distal colon portion. In the second experiment, 15% guar gum as such and in admixture with ferric ammonium sulfate (0.12%) were compared with the respective controls, the first of 20 weekly dosages of DMH being administered on day 28 of the feeding. At 32 weeks following injection 1, the overall lesion differences were not remarkable, but the guar gum ratios engendered decreases in the distal colon tumor frequencies. In general, lesion incidence was extensive, involving 80-100% of the animals per group of the 2 series. Adenocarcinomas occurred in the small intestine and were more prominent in the control and 15% guar gum dietary groups but fewer with the ferric ammonium sulfate supplement.