Journal Article

Dietary prevention of azoxymethane-induced colon carcinogenesis with rice-germ in F344 rats

Kunihiro Kawabata, Takuji Tanaka, Taro Murakami, Tadashi Okada, Hiromichi Murai, Tomohiro Yamamoto, Akira Hara, Masahito Shimizu, Yasuhiro Yamada, Kengo Matsunaga, Toshiya Kuno, Naoki Yoshimi, Shigeyuki Sugie and Hideki Mori

in Carcinogenesis

Volume 20, issue 11, pages 2109-2115
Published in print November 1999 | ISSN: 0143-3334
Published online November 1999 | e-ISSN: 1460-2180 | DOI:
Dietary prevention of azoxymethane-induced colon carcinogenesis with rice-germ in F344 rats

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The modifying effect of dietary administration of defatted rice-germ and γ-aminobutyric acid (GABA)-enriched defatted rice-germ on azoxymethane (AOM)-induced colon carcinogenesis was investigated in two experiments with male F344 rats. In the first experiment (the pilot study), the effects of the defatted rice-germ, the GABA-enriched defatted rice-germ and rice-germ on AOM-induced (15 mg/kg body wt once a week for 3 weeks) formation of aberrant crypt foci (ACF) were examined. The latter two preparations (2.5% in the diet) significantly inhibited ACF formation (P < 0.005). In the second experiment, a long-term study of the effects of rice-germ was done. One group was treated with AOM alone, four groups received the carcinogen and were fed the diets containing 2.5% rice-germ or 2.5% GABA-enriched defatted rice-germ for 5 (initiation phase) or 30 weeks (post-initiation phase), two groups were treated with rice-germ or GABA-enriched defatted rice-germ alone and one group was kept on the basal diet. At the termination of the study, dietary exposure to rice-germ during the initiation phase significantly reduced the incidence of colonic adenocarcinoma (71 versus 29%, P < 0.01). GABA-enriched defatted rice-germ or rice-germ during the post-initiation phase also decreased the frequency of colonic adenocarcinoma (71 versus 20%, GABA-enriched defatted rice-germ feeding, P < 0.01; 27%, rice-germ feeding, P < 0.01). These data suggest that constituents of rice-germ are possible dietary preventatives for human colon cancers.

Keywords: ACF, aberrant crypt foci; AOM, azoxymethane; GABA, γ-aminobutyric acid; PCNA, proliferating cell nuclear antigen.

Journal Article.  4910 words.  Illustrated.

Subjects: Clinical Cytogenetics and Molecular Genetics

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