Ward W E, Jiang F O, Thompson L U
Department of Nutritional Sciences, University of Toronto, Toronto, ON, Canada M5S 3E2.
Nutr Cancer. 2000;37(2):187-92. doi: 10.1207/S15327914NC372_11.
Previous investigation demonstrated that feeding a 10% flaxseed (10F) diet during pregnancy and lactation enhanced the differentiation of highly proliferative terminal end bud (TEB) structures of rat mammary gland into less proliferative alveolar buds and lobules. From this study, it was hypothesized that the lignan component in flaxseed mediated the observed effects. Because mammary glands with more TEBs are more susceptible to carcinogens, exposure to flaxseed during early postnatal life may reduce the risk of developing mammary cancer. Our objectives were to elucidate whether exposure to flaxseed during lactation only and during pregnancy and lactation can similarly influence the differentiation of mammary gland structures and also to identify whether the lignan component of flaxseed is the biologically active agent. Offspring were exposed to a 10F diet or a dose of purified lignan equivalent to that in a 10F diet (10S) during lactation only or from lactation to postnatal Day 50. Compared with controls, exposure to 10F or 10S during lactation only or from lactation to postnatal Day 50 reduced the number of TEBs and resulted in a rise in the number of alveolar buds. In conclusion, exposure to flaxseed or its purified lignan during lactation is a critical period in which mammary gland development may be promoted by enhancing the differentiation of the mammary gland structures. However, continuous exposure, particularly to purified lignans, resulted in the most differentiation of the mammary gland. The next step is to determine whether the changes in mammary gland structures are chemopreventive in rats challenged with a carcinogen.
先前的研究表明，在怀孕和哺乳期喂食10%亚麻籽（10F）饮食可促进大鼠乳腺中高增殖性终末芽（TEB）结构分化为增殖性较低的腺泡芽和小叶。基于这项研究，推测亚麻籽中的木脂素成分介导了所观察到的效应。由于具有更多TEB的乳腺对致癌物更敏感，因此在出生后早期接触亚麻籽可能会降低患乳腺癌的风险。我们的目标是阐明仅在哺乳期以及在怀孕和哺乳期接触亚麻籽是否会同样影响乳腺结构的分化，并确定亚麻籽中的木脂素成分是否为生物活性剂。仅在哺乳期或从哺乳期到出生后第50天，让后代接触10F饮食或相当于10F饮食中木脂素剂量的纯化木脂素（10S）。与对照组相比，仅在哺乳期或从哺乳期到出生后第50天接触10F或10S可减少TEB的数量，并导致腺泡芽数量增加。总之，在哺乳期接触亚麻籽或其纯化木脂素是一个关键时期，在此期间，通过增强乳腺结构的分化可促进乳腺发育。然而，持续接触，尤其是接触纯化木脂素，会导致乳腺分化最为明显。下一步是确定在受到致癌物攻击的大鼠中，乳腺结构的变化是否具有化学预防作用。
