Preventive effects of yogurt on DMH-induced preneoplastic lesions of colon in F344 rats

• Main Authors: Ming-Shiuan Lin, 林明萱
• Other Authors: Chun-Kuang Shih
• Format: Others
• Language: zh-TW
• Published: 2010
• Online Access: http://ndltd.ncl.edu.tw/handle/00755920189451241423

碩士 === 臺北醫學大學 === 保健營養學研究所 === 98 === Malignancy is the first leading cause of death in Taiwan. Colorectal cancer, the third cause of cancer death in Taiwan, is the form of cancer most associated with diet. Yogurt is produced based on milk and fermented by probiotics. Previous study showed that milk and yogurt could prevent colorectal cancer. The purpose of this study was to assess the preventive effect of milk and yogurts fermented by various probiotics on the development of colorectal cancer. F344 rats were fed distilled water (negative control), piroxicam (positive control), milk, bsal yogurt (Streptococcus thermophilus and Lactobacillus bulgaricus), yogurt A (S. thermophilus, L. bulgaricus and L. acidophilus), yogurt B (S. thermophilus, L. bulgaricus and Bifidobacterium lactis) or yogurt AB (S. thermophilus, L. bulgaricus, L. acidophilus and B. lactis). After one week of feeding, rats were injected intraperitoneally with 1,2-dimethylhydrazine to induce colon carcinogenesis. After 10 weeks of feeding, rats were sacrificed. The cecal contents were examined for pH and β-glucuronidase activity; the colons were examined for aberrant crypt foci (ACF), mucin production, and the colonic mucosa for pro-inflammatory cyclooxygenase-2 (COX-2), inducible nitric oxide synthase (iNOS) protein expression; the blood were were examined for imunoglobulin A (Ig A) levels. The results showed that there were no significant differences in cecal pH and β-glucuronidase activity among groups. Postive control, milk, basal yogurt, yogurt A and yogurt AB significantly reduced the numbers of ACF and aberrant crypts in the colon as compared to negative control. Basal yogurt, yogurt A and yogurt AB significantly reduced the number of sialomucin-producing ACF in the distal colon as compared to negative control. There were no significant differences in mucin-depleted foci (MDF) number among groups. Yogurt B and AB significantly increased the COX-2 protein expression of the proximal colon as compared to negative control. All yogurt groups significantly reduced the plasma Ig A levels as compared to negative control. This study showed that basal yogurt and yogurt A and yogurt AB significantly inhibited the early markers of colorectal cancer after 10-week feeding, suggesting that these yogurts may inhibit colon carcinogenesis via mucin modification.