Experimental evidence highlights the importance of dietetic factors on breast cancer. In this work we aimed to analyze the effects two oils, corn oil (rich in n-6 polyunsaturated fatty acids -PUFA-) and extra virgin olive oil (EVOO), on oxidative stress in an animal model of breast carcinogenesis. Female rats were fed a low-fat control, a high-corn oil, or a high-EVOO diet from weaning or after induction with 7,12-dimethylbenz[a]anthracene at 53 days. Animals were euthanized at 36, 51, 100 and 246 days of age. We analyzed antioxidant enzymes (mRNA and activity of superoxide dismutase, glutathione peroxidase and catalase), non-enzymatic capacity (oxidized and reduced glutathione) and DNA damage (8-oxo-dG) in tumors and mammary gland at different ages. We also analyzed lipid peroxidation (isoprostanes in serum and lipofuscin in liver). Results indicated a decrease in the enzymatic antioxidant capacity and increased oxidative stress in mammary gland of healthy young animals after a short period of high-fat diets intake, followed by an adaptation to chronic dietary intervention. After induction both diets, especially the one high in n-6 PUFA, increased the oxidized glutathione. In tumors no clear effects of the high-fat diets were observed, although in the long-term lipofuscin and 8-oxo-dG suggested greater oxidative damage by effect of the n-6 PUFA-rich diet. Considering the differential effects of these diets on mammary carcinogenesis that we have previously reported, this study suggests that these high-fat diets could have an effect on oxidative stress that would lead to different signaling pathways.

实验证据突出了饮食因素对乳腺癌的重要性。在这项工作中，我们旨在分析两种玉米油（富含n-6多不饱和脂肪酸-PUFA-）和特级初榨橄榄油（EVOO）对乳腺癌致癌动物模型中氧化应激的影响。雌性大鼠断奶后或在第53天用7,12-二甲基苯并[a]蒽诱导后，饲喂低脂对照，高玉米油或高EVOO饮食。在36、51、100和246天时对动物实施安乐死。我们分析了不同年龄的肿瘤和乳腺中的抗氧化酶（mRNA和超氧化物歧化酶，谷胱甘肽过氧化物酶和过氧化氢酶的活性），非酶能力（氧化型和还原型谷胱甘肽）和DNA损伤（8-oxo-dG）。我们还分析了脂质过氧化作用（血清中的异前列腺素和肝脏中的脂褐素）。结果表明，短期摄入高脂饮食后，健康的幼小动物的乳腺中的酶促抗氧化能力下降，氧化应激增加，随后适应慢性饮食干预。诱导后，两种饮食，特别是n-6 PUFA中的一种饮食，都增加了氧化型谷胱甘肽。在肿瘤中，没有观察到高脂饮食的明显作用，尽管在长期脂褐素和8-oxo-dG中，富含n-6 PUFA的饮食对氧化损伤的影响更大。考虑到我们之前已经报道过的这些饮食对乳腺癌致癌作用的不同影响，这项研究表明，这些高脂饮食可能会对氧化应激产生影响，从而导致不同的信号传导途径。