饲料脂肪酸组成对大鼠胃肠等肿瘤生成的影响

目的：　研究脂肪酸组成对甲基亚硝基脲（ Ｍ Ｎ Ｕ） 诱导的大鼠结肠等肿瘤生成的影响。方法：　雄性 Ｓ Ｄ 大鼠喂以用牛油、豆油、紫草油、玉米油和鱼油按不同比例调配，含脂肪量为１５ ％ 的半合成饲料，分５ 组。各组脂肪酸组成为：１ 组以牛油为主富含饱和脂肪酸；２ 组以豆油为主富含亚油酸，１ 组和２ 组基本不含有ｎ ３ 系列多不饱和脂肪酸；３ 组以紫草油为主富含亚油酸，α和γ亚麻酸，ｎ ６／ｎ ３ 脂肪酸之比为４ ．５３ ；４ 组以鱼油为主富含ｎ ３ 系列多不饱和脂肪酸，ｎ ６／ｎ ３ 脂肪酸之比为０ ．７３ ；５ 组为混合油组，ｎ ６／ｎ ３ 脂肪酸之比为１ ．９５ 。对照组和实验组分别经腹腔注射磷酸盐生理盐水缓冲液和３０ ｍｇ／ｋｇ ．ｂｗ 的 Ｍ Ｎ Ｕ，每周一次，共６ 次，喂养１８０ 天。实验期控制了影响肿瘤产生的因素。结果：１ 、２ 和３ 组产生的结肠肿瘤均显著高于４组（ Ｐ＜ ０ ．０５） ，也相对高于５ 组（ Ｐ＞ ０ ．０５） ；１ 、２ 、３ 和５ 组产生的胃肿瘤也相对地高于４ 组，但是，各组之间无显著的统计学差异。除了４ 组和１ 组外，其它各组在其它部位也产生了肿瘤。结论：　 Ｍ Ｎ Ｕ 能诱导喂以不同脂肪酸组成的大鼠产生以结肠癌为主的癌症；饲?

EFFECT OF DIETARY FATTY ACIDS COMPOSITION ON COLON AND OTHER TUMORS IN RATS

Objective: In order to study the effect of dietary fatty acids composition on colon and other tumors induced by tumorigenic chemical in rats. Methods: Male SD strain rats were divided randomly into 10 groups respectively. They were fed on five kinds of diets which were composed of beef tallow, soybean oil, alkana oil, corn oil, and fish oil in different amounts, and the content of fat in diets was 15% (W/W). The fat in the first group was mainly from beef tallow, in which saturated fatty acids was about 47%. The fat in the second group was mainly from soybean oil, in which linoleic acid was about 56%. There was no n 3 polyunsaturated fatty acid (PUFA) in these two groups. The fat in the third group was mainly from alkana oil, which was enriched with linoleic acid and linolenic acid and their total content was about 65.7%. The ratio of n 6 PUFA to n 3 PUFA was about 4.53. The fat in the forth group was mainly from fish oil, which was enriched with n 3 PUFA and its total content was about 39.8%. The ratio of n 6 PUFA to n 3 PUFA was about 0.73. The fat in the fifth group was from different oils in which the ratio of n 6 PUFA to n 3 PUFA was 1.95. Five control groups and experimental groups were injected intraperitoneally phosphate buffer solution and 30 mg/kg bw methyl nitrosourea (MNU) respectively once a week for 6 times. The factors that might induce cancer were well controlled. Results: Rats fed on different fatty acid compositions could be induced colon and other tissue tumors by MNU. The number of colon tumor developed in 1, 2, and 3 groups was significantly higher than that in the forth group (X 2=10.55,P<0.05), and also relatively higher than that in the fifth group. The number of gastric tumor developed in the 1, 2, 3 and 5 groups was slightly higher than in the forth group. Except for the forth and the first group, there were some tumors developed in other tissues. Conclusion: The better fatty acids composition in terms of inhibiting the tumor development induced by MNU is that the saturated, monounsaturated and polyunsaturated fatty acids are 13.9%, 16.4% and 68.8% respectively.