Chemopreventive effect of fermented brown rice and rice bran on 4-nitroquinoline 1-oxide-induced oral carcinogenesis in rats.
The preventive effects of the dietary administration of brown rice and rice bran fermented with Aspergillus oryzae (FBRA) on oral carcinogenesis induced by 4-nitroquinoline 1-oxide (4-NQO) were investigated in male F344 rats. At 7 weeks of age, the animals were given 20 ppm 4-NQO in their drinking water for 8 weeks to induce tongue neoplasms. Groups of rats were fed diets containing 5 or 10% FBRA during the initiation or postinitiation phases of the 4-NQO-induced oral carcinogenesis. The other groups consisted of rats fed 10% FBRA or untreated rats. At the termination of the study (week 32), the incidences, multiplicities of tongue lesions (pre-neoplasms and neoplasms) and the cell proliferation activity estimated by the 5-bromodeoxyuridine (BrdU)-labeling index were compared among the groups. Feeding of 5% FBRA during the initiation phase significantly decreased the incidence (68.2 vs 36.8%; p<0.05) and multiplicity (1.05+/-0.84 vs 0.37+/-0.50; p<0.005) of the tongue carcinoma. When feeding of 10% FBRA occurred after the 4-NQO exposure, the multiplicity of tongue carcinoma was also reduced (1.05+/-0.84 vs 0.52+/-0.60; p<0.05). In addition, the dietary administration of FBRA at both doses significantly decreased the BrdU-labeling index in the oral squamous epithelium (p<0.05). Although a dose-dependent response was not observed, FBRA is effective in suppressing the development of 4-NQO-induced oral carcinogenesis by its concurrent exposure to the carcinogen. The inhibitory effect could be related to the suppression of the hyperproliferation of cells in the tongue epithelium and the radical scavenging activity of FBRA.
Long
Nguyen Khanh
NK
Department of Oral and Maxillofacial Sciences, Gifu University, Graduate School of Medicine, Gifu 501-1194, Japan.
Makita
Hiroki
H
Yamashita
Tomomi
T
Toida
Makoto
M
Kato
Keizo
K
Hatakeyama
Daijiro
D
Shibata
Toshiyuki
T
D000818:Animals; D001973:Bromodeoxyuridine / Q000032:analysis / Q000378:metabolism; D002471:Cell Transformation, Neoplastic / Q000139:chemically induced; D003497:Cyclic N-Oxides / Q000633:toxicity; D004043:Dietary Fiber / Q000008:administration & dosage / Q000627:therapeutic use*; D008297:Male; D009062:Mouth Neoplasms / Q000139:chemically induced / Q000517:prevention & control*; D012275:Oryza; D011230:Precancerous Conditions / Q000139:chemically induced / Q000517:prevention & control*; D051381:Rats; D011916:Rats, Inbred F344
D003497:Cyclic N-Oxides; D004043:Dietary Fiber; D001973:Bromodeoxyuridine; C013620:4-nitropyridine 1-oxide