中文摘要：

目的探讨不同n-6／n-3多不饱和脂肪酸（PUFA）膳食构成比对MNU诱导的乳腺癌大鼠血清雌二醇水平及乳腺组织CYP17、CYP19 mRNA表达的影响。方法雌性SD大鼠65只随机分为5组，即n-6PUFA组、10：1n-6／n-3组、5：1n-6／n-3组、1：1n-6／n-3组和正常对照组，前4组以50rag／kgMNU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周时经阴道涂片证实间情期，股动脉取血液并剖取乳腺组织，采用放射免疫法检测血清雌二醇水平，利用RT—PCR技术检测乳腺组织中CYP17、CYP19 mRNA表达状况。结果4组乳腺癌大鼠血清雌二醇水平及乳腺组织中CYP17、CYP19的表达较正常对照组均有所升高，其中n-6组最高，其余各组随n-6／n-3值减小而下降，1：1n-6／n．3组显著低于n-6组。结论不同n-6／n-3PUFA膳食构成比对MNU诱导的乳腺癌大鼠血清雌二醇水平及乳腺组织CYP17、CYP19mRNA的表达具有不同影响，1：1n-6／n-3PUFA膳食构成比能有效抑制乳腺癌大鼠血清雌二醇水平及乳腺组织CYP17、CYP19 mRNA表达的升高。

英文摘要：

Objective To observe the effect of n-6/n-3 polyunsaturated fatty acid dietary of different constituent ratio on the serum level of estradiol and expressions of CYP17, CYP19 in MNU-induced rat breast cancer tissues. Methods Totally 65 female SD rats were randomly divided into 5 groups： n-6 PUFA, 10：1 n-6/n- 3 PUFA, 5：1 n-6/n-3 PUFA, 1：1 n-6/n-3 PUFA and normal control. Except control group receiving physiological saline, all rats were given a single intraperitoneal injection of MNU （50 mg/kg） and switched to different diets containing fatty acids mentioned above. After 8 and 18 weeks, the serum level of estradiol and expressions of CYP17, CYP19 in the breast tissues of different groups were determined by RIA and RT-PCR. Results The serum level of estradiol and expressions of CYP17, CYP19 in rat breast cancer tissues were higher than normal control, highest in n-6 group and gradually decreased with the ratio of n-6/n-3 decreasing. Conclusion n-6/n-3 PUFA dietary of different constituent ratio can diversely influence the serum level of estradiol and expressions of CYP17, CYP19 in MNU-induced rat breast cancer tissues, n-6/n-3 PUFA dietary with constituent ratio of 1：1 can significantly inhibit the increased serum level of estradiol and increased expressions of CYP17, CYP19 in breast cancer tissues.