Journal Article

Ingestion of sugar beet fiber enhances irradiation-induced aberrant crypt foci in the rat colon under an apoptosis-suppressed condition

Satoshi Ishizuka, Satoshi Ito, Masashi Onuma, Takanori Kasai, Yoritaka Aoyama and Hiroshi Hara

in Carcinogenesis

Volume 20, issue 6, pages 1005-1009
Published in print June 1999 | ISSN: 0143-3334
Published online June 1999 | e-ISSN: 1460-2180 | DOI: http://dx.doi.org/10.1093/carcin/20.6.1005
Ingestion of sugar beet fiber enhances irradiation-induced aberrant crypt foci in the rat colon under an apoptosis-suppressed condition

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The induction of aberrant crypt foci (ACF) by irradiation of γ-rays (60Co), and the effect of dietary sugar beet fiber (SBF) on irradiation-induced ACF were examined. We found that abdominal irradiation of γ-rays could induce ACF in the rat colon. The irradiation was performed once a week at a dose rate of 2 or 3 Gy per irradiation. Irradiation-induced ACF were observed in the colon at 10 weeks after the first irradiation at dose of 2 Gy for six times or 3 Gy for four times. Dietary SBF had no effect on the number of ACF, aberrant crypts (AC) or AC/focus induced by abdominal γ-irradiation. However, an ingestion of SBF resulted in an increase in the number of these parameters in apoptosis-suppressed rats by cycloheximide (CHX). An injection of CHX suppressed irradiation-induced apoptosis of the colonic epithelial cells for at least 6 h after the irradiation. In CHX-injected rats, an ingestion of SBF significantly increased the number of ACF, AC and AC/focus compared with fiber-free fed rats at 9 weeks after the first irradiation. On the other hand, in saline-injected rats, no significant difference was found between SBF and fiber-free diets in the number of ACF, AC and AC/focus through the experimental period. These results suggest that dietary SBF may be involved in the elimination of abnormal cells from an irradiated colon through the apoptosis of colonic epithelial cells. In this study, we have shown a new method for inducing ACF by using γ-rays which were not influenced by luminal contents such as bacterial enzyme, at least in the initiation stage.

Keywords: AC, aberrant crypts; ACF, aberrant crypt foci; AOM, azoxymethane; CHX, cycloheximide; DMH, 1,2-dimethylhydrazine; SBF, sugar beet fiber; TUNEL, terminal deoxynucleotidyl transferase-mediated nick end labeling.

Journal Article.  4493 words.  Illustrated.

Subjects: Clinical Cytogenetics and Molecular Genetics

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