不同膳食脂肪酸构成影响MNU诱导大鼠乳腺肿瘤发生的研究

目的:探讨不同膳食脂肪酸对甲基亚硝基脲(MNU)诱导的大鼠乳腺肿瘤发生的影响。方法:用含15%脂肪(wt/wt)的半合成饲料喂养雌性SD大鼠。大鼠50d龄时,分8组喂养8种不同膳食脂肪酸组成的饲料,即SFA、MUFA、n-6PUFA、n-3PUFA、1∶1n-6/n-3、5∶1n-6/n-3、10∶1n-6/n-3和S/M/P为1∶2∶(1其中n-6/n-3为1∶1),每组又分肿瘤组和对喂组,肿瘤组,单次腹腔注射MNU(50mg/kgbw),相应的对喂组注射生理盐水,持续喂养18w。观察各组大鼠体重增长、乳腺肿瘤发生率、肿瘤多发率及肿瘤潜伏期等。结果:除喂养n-3PUFA的大鼠在实验6w后出现体重增长受阻外,其它组别的大鼠体重增长无明显差异。各对喂组大鼠均无乳腺肿瘤发生,而在MNU注射组中,喂养n-3PUFA的大鼠也无乳腺肿瘤发生,但喂养SFA、MUFA、n-6PUFA、5∶1n-6/n-3、10∶1n-6/n-3和S/M/P(1/2/1)大鼠乳腺肿瘤诱发率是1∶1n-6/n-3的2倍,且喂养1∶1n-6/n-3的大鼠,其肿瘤发生的潜伏期也最长。结论:不同膳食脂肪酸构成对MNU诱导的大鼠乳腺肿瘤发生影响不同。,1∶1n-6/n-3膳食脂肪酸构成能有效抑制MNU诱导的乳腺肿瘤发生。

STUDY ON THE EFFECT OF DIFFERENT DIETARY FATTY ACID COMPOSITIONS ON MNU-INDUCED BREAST TUMORS IN RATS

Objective: To study the effect of different dietary fatty acid compositions on breast tumors induced by methyl-nitrosourea(MNU) in rats. Method: Female SD rats were fed diets containing 15% fat (wt/wt) in the experimental period. At age of 50d, rats were randomly assigned to 8 groups and each group was suldivided into tumor group and control group. The tumor group was given a single ip injection of MNU (50 mg/kg bw) and switched to one of 8 different diets containing following fatty acids: saturated fatty acid(SFA); monounsaturated fatty acid(MUFA); n-6 polyunsaturated fatty acid(PUFA); n-3 PUFA; 1∶1 n-6/n-3; 5∶1 n-6/n-3; 10∶1 n-6/n-3; 1∶2∶1 S/M/P(n-6/n-3 at 1∶1) for 18w. The control groups received the physiological saline only. The weight growth, mammary tumor incidence, tumor multiplicity, and tumor latency were observed. Results: Except the weight growth was arrested in rats fed on n-3 PUFA 6w later, there was no significant difference in weight growth among the other groups. Additionally, there was no mammary tumor occurrence in control groups, but in model groups, the incidence of mammary tumors in rats fed on SFA, MUFA, n-6 PUFA,5∶1 n-6/n-3, 10∶1 n-6/n-3 and 1∶2∶1 S/M/P diets was twice higher than that in rats fed on 1∶1 n-6/n-3 diet, although there was also no tumorin rats fed on n-3 PUFA diet. Moreover, tumor multiplicity in rats fed on 1∶1 n-6/n-3 diet was obviously decreased in comparison with those groups, and tumor latency was prolonged too. Conclusion: The different dietary fatty acid compositions can diversely influence MNU-induced breast tumors incidence in rats and 1∶1 n-6/n-3 has obvious inhibitory effect.