| Co-Investigator(Kenkyū-buntansha) |
ITOH Toshio Central Inst. of Exp. Anim., Group Director (Researcher), 実験動物中央研究所, 室長(研究職) (20106644)
NOMURA Tatsuji Central Inst. of Exp. Anim., Head (Researcher), 実験動物中央研究所, 所長(研究職) (10072399)
ITOH Kikuji Graduate School of Agriculture and Life Sciences, The University of Tokyo, Asosc. Prof., 大学院・農学生命科学研究科, 助教授 (50100045)
NAKAYAMA Hiroyuki Graduate School of Agriculture and Life Sciences, The University of Tokyo, Associate Prof., 大学院・農学生命科学研究科, 助教授 (40155891)
HIOKI Kyouji Central Inst. of Exp. Anim., Group Director (Researcher), 実験動物中央研究所, 室長(研究職) (80208735)
|
|---|
| Research Abstract |
1. To study the effects of intestinal flora on cancer development, N-methyl-nitrosourea (MNU) and N,N-diethylnitrosoamine (DEN), which induce the mutations in c-Ha-ras genes, were injected to germfree and various types of gnotobiote rasH2 mice. There were no relation between cancer development and the composition of intestinal flora.
2. Although rasH2 mice were inoculated with Aαc, one of heterocyclic amines, and aflatoxin, which are strong carcinogens and ingested from the daily diet, no cancers were observed.
3. Inhibitory effect of various functional foods was studied using rasH2 mice injected with 1,2-dimethylhydrazine (DMH). Apple pectin and culture condensate of Bifidobacterium longum inhibited colorectal tumors. However there were no relation between development of colorectal tumors and the intestinal environments, e.g. composition of intestinal flora, concentrations of organic acids and putrefactive products, composition of bile acids.
4. Culture of Propionibacterium freudereichii, which is used as starter of cheese and is immunomodulator, did not inhibit the colorectal tumors in rasH2 mice induced by DMH. Yogurt, fermented milk by Streptococcus thermophilus and Lactobacillus burgaricus, reduced the incidence of the colorectal tumors in rasH2 mice induced by DMH. Fermented soy bean protein by single culture of Lactobacillus casei, L. fermentum, Saccharomyces cerevisiae or mixed culture of them could inhibited the colorectal tumors, but not fermented protein by Leuconostoc mesenteroides and mixed culture of this with other three strains.
These results indicate that rasH2 mice are good animal model to evaluate the inhibitory effects of functional food on the colorectal tumors.
|
