Sakaguchi M, Minoura T, Hiramatsu Y, Takada H, Yamamura M, Hioki K, Yamamoto M
Cancer Res. 1986 Jan;46(1):61-5.
To determine whether the kind of dietary fat affects colon carcinogenesis, male Donryu rats were fed a 5% fat diet containing linoleate, an unsaturated fat, or stearate, a saturated fat, in semipurified fat-free chow. The rats were given azoxymethane (7.4 mg/kg body weight) s.c. once a week for 11 weeks and killed 15 weeks after the last injection of the carcinogen. The rats on the unsaturated fat diet had a significantly higher incidence of colon tumors. Fatty acid analysis of cholesterol esters in the liver and examination of the amount of fecal bile acids showed that the unsaturated fat diet increased the level of cholesterol linoleate and arachidonate in the liver and also increased the fecal excretion of bile acids, especially that of lithocholic acid. The colon tumors in rats on the unsaturated fat diet, compared with those in rats on the saturated fat diet, contained a higher level of lysophosphatidylcholine. These results suggest that increased fecal excretion of bile acids due to increased polyunsaturated cholesterol esters in the liver stimulates phospholipase A2 activity of colon initiated cells and enhances colon carcinogenesis in rats on the unsaturated fat diet.
为了确定膳食脂肪的种类是否会影响结肠癌的发生，将雄性唐利玉大鼠饲养在半纯化的无脂肪饲料中，饲料含5%的脂肪，其中一种含不饱和脂肪亚油酸酯，另一种含饱和脂肪硬脂酸酯。大鼠每周一次皮下注射偶氮甲烷（7.4毫克/千克体重），持续11周，并在最后一次注射致癌物15周后处死。食用不饱和脂肪饮食的大鼠结肠肿瘤发病率显著更高。对肝脏中胆固醇酯进行脂肪酸分析以及检测粪便胆汁酸的量，结果显示不饱和脂肪饮食会增加肝脏中胆固醇亚油酸酯和花生四烯酸酯的水平，还会增加胆汁酸的粪便排泄量，尤其是石胆酸的排泄量。与食用饱和脂肪饮食的大鼠相比，食用不饱和脂肪饮食的大鼠的结肠肿瘤中溶血磷脂酰胆碱水平更高。这些结果表明，肝脏中多不饱和胆固醇酯增加导致胆汁酸粪便排泄增加，会刺激结肠起始细胞的磷脂酶A2活性，并增强食用不饱和脂肪饮食大鼠的结肠癌发生。
