Arakaki Junya, Suzui Masumi, Morioka Takamitsu, Kinjo Tatsuya, Kaneshiro Tatsuya, Inamine Morihiko, Sunagawa Nao, Nishimaki Tadashi, Yoshimi Naoki
Tumor Pathology, University of the Ryukyus Faculty of Medicine, Okinawa 903-0215, Japan.
Asian Pac J Cancer Prev. 2006 Jul-Sep;7(3):467-71.
The purpose of the present study was to examine whether Neem leaf (Azadirachta indica) has short-term chemopreventive effects on endpoint preneoplastic lesions involved in rat colon carcinogenesis and might also exert antioxidative activity. Forty- two male F344 rats were randomly divided into 6 experimental groups. Groups 1 to 4 were given a subcutaneous injection of azoxymethane (AOM, 20 mg/kg body weight) once a week for 2 weeks. Starting one week before the first injection of AOM, rats in groups 2 to 4 received an aqueous extract of Neem leaf (20, 100, and 250 mg/kg, respectively) by gavage 3 times per week, for 5 weeks. Rats in group 5 also were given the Neem extract by gavage feeding 3 times per week for 5 weeks, while group 6 served as untreated controls. The experiment was terminated 5 weeks after the start. Dietary feeding of the Neem extract at all dose levels significantly inhibited the induction of aberrant crypt foci (ACF) (P<0.0002), when compared to the AOM-treated group (group 1). In groups 2 to 4, treatment of rats with the Neem extract also significantly decreased the proliferating cell nuclear antigen (PCNA) labeling indices (P<0.0006) of colon epithelium and ACF. Moreover, the Neem extract also showed antioxidative activity. The finding that dietary Neem has possible chemopreventive effects in the present short-term colon carcinogenesis bioassay suggests that longer-term exposure may cause suppression of tumor development.
本研究的目的是检验印楝叶（印楝）对大鼠结肠癌发生过程中的终点癌前病变是否具有短期化学预防作用，以及是否还具有抗氧化活性。42只雄性F344大鼠被随机分为6个实验组。第1至4组每周皮下注射一次氧化偶氮甲烷（AOM，20毫克/千克体重），共注射2周。从首次注射AOM前一周开始，第2至4组的大鼠每周经口灌胃3次印楝叶水提取物（分别为20、100和250毫克/千克），持续5周。第5组的大鼠也每周经口灌胃3次印楝提取物，持续5周，而第6组作为未处理的对照组。实验在开始5周后终止。与AOM处理组（第1组）相比，所有剂量水平的印楝提取物饮食喂养均显著抑制了异常隐窝灶（ACF）的诱导（P<0.0002）。在第2至4组中，用印楝提取物处理大鼠也显著降低了结肠上皮和ACF的增殖细胞核抗原（PCNA）标记指数（P<0.0006）。此外，印楝提取物还表现出抗氧化活性。在本短期结肠癌发生生物测定中，饮食中添加印楝具有可能的化学预防作用这一发现表明，长期接触可能会抑制肿瘤发展。
