脂肪酸组成对化学物诱导的结肠癌变危险性机理的研究

Research on the mechanism of the fatty acid composition on the tumorigenic danger induced by chemical tumorigenic material

大鼠喂以含１５％脂肪，但是脂肪酸组成不一致的５组半合成饲料，实验期给以甲基亚硝基脲诱导结肠肿瘤，观察脂肪组成对处于增生危险的大鼠结肠粘膜的增生细胞核抗原（ＰＣＮＡ）、碱性磷酸酶活性（ＡＬＰ）、膜脂流动性、前列腺素Ｅ２（ＰＧＥ２）及细胞动力学的影响。结果表明：含饱和脂肪酸和单不饱和脂肪酸成分最少而含ｎ－６多不饱和脂肪酸（ＰＵＦＡ）成分最高的第３组，ＰＣＮＡ和ＰＩ标志的Ｓ期细胞数最多，ＡＬＰ活性较高；含ｎ－３ＰＵＦＡ比例最高的第４组，ＰＣＮＡ和ＰＩ标志的Ｓ期细胞数、ＡＬＰ活性及ＰＧＥ２含量最少，而膜脂流动性最好。结果提示，含ｎ－３ＰＵＦＡ较高比例的脂肪酸组成降低由化学物诱导的结肠癌变危险性，其机制之一可能是，通过减少结肠粘膜ＰＣＮＡ、ＰＩ标志的Ｓ期细胞数、ＡＬＰ活性、保护膜脂流动性及减少ＰＧＥ２生成等进行。

Rats were given 5 kinds of diets which contained 15% (w/w)fat and different fatty acids composition. The rats were given methyl nitrosurea (MNU) to induce colonic tumor. Proliferation cell nuclear antigen (PCNA), cell kinetics, membrane fluidity, the activity of alkaline phosphatase (ALP) and the content of prostaglandin E 2(PGE 2) in colonic mucosa were determined in order to assess the fatty acids composition on the colonic cell tumorigenesis. The results indicated that the cells of PCNA, cells of PI labeled in S period and the activity of ALP were the highest in the 3rd group which contained lowest saturated fatty acids (SFA) and monounsaturated fatty acids (MUFA) and highest n 6 polyunsaturated fatty acids. Whereas ,these indexes and PGE 2 were lowest and membrane fluidity was the best in the 4th group which contained the highest n 3 PUFA. It is considered that the inhibition tumorigenesis of n 3 PUFA may be related to its effects of decreaing PCNA, PGE 2,cells in S period and increasing membrane fluidity.