中文摘要：

目的 探讨不同比例n-6／n-3多不饱和脂肪酸（PUFA）对甲基亚硝基脲（MNU）诱导的乳腺癌大鼠乳腺癌易感基因（BRCA1）表达的影响。方法 雌性SD大鼠65只随机分为5组，即n-6PUFA组、10：1 n-6／n-3组、5：1n-6／n-3组、1：1n6／n-3组和正常对照组，前四组以50mg／kg体重MNU单次腹腔注射诱导大鼠乳腺肿瘤发生，正常对照组注射等体积无菌生理盐水。给药后立即分组喂养不同饲料，并在8周和18周时处死动物剪取乳腺组织，利用RT—PCR和Western blot技术检测组织中BRCA1 mRNA和蛋白表达状况。结果 四组乳腺癌大鼠BRCA1表达较正常对照组均有所下降．四组中BRCA1的表达以1：1 n-6／n-3组最强，并随n-6／n-3比值增大而下降。结论 不同膳食脂肪酸构成对MNU诱导的乳腺癌大鼠BRCA1的表达具有不同影响，1：1 n-6／n-3膳食脂肪酸构成能有效抑制乳腺癌大鼠BRCA1表达的下降。

英文摘要：

Objective To observe the effect of different ratio of n-6/n-3 polyunsaturated fatty acid on expression of BRCA1 in the MNU-induced breast cancer rats.Methods 65 female SD rats were randomly divided into 5 groups： n-6, 10：1 n-6/n-3, 5：1 n-6/n-3,1：1 n-6/n-3 and normal controlled group. Except controlled group received physiological saline, all rats were given a single ip injection of MNU （50mg/kg BW） and switched to different diets containing fatty acids mentioned above. After 8w and 18w, the expressions of BRCA1 in the breast tissue of different group were determined by RT-PCR and Western blot.Results The expressions of BRCA1 in breast cancer rats were lower than normal control, they were highest in the 1：1 n-6/n-3 group and gradually decreased with the ratio of n-6/n-3 increasing. Conclusion Different dietary fatty acid compositions can diversely influence the expression of BRCA1 in MNU-induced breast cancer rats; 1：1 n-6/n-3 can significantly inhibit the decrease of BRCA1 expression in breast cancer rats.