Exposure to flaxseed or its lignan component during different developmental stages influences rat mammary gland structures

• Published in: Carcinogenesis (New York) Vol. 20; no. 9; pp. 1831 - 1835
• Main Authors: Tou, Janet C.L., Thompson, Lilian U.
• Format: Journal Article
• Language: English
• Published: Oxford Oxford University Press 01-09-1999; Oxford Publishing Limited (England)
• Subjects: 10% flaxseed; 10F; 5% flaxseed; ALA; alpha-Linolenic Acid - pharmacology; alpha-Linolenic Acid - therapeutic use; alveolar bud; Animal Feed; Animals; Anticarcinogenic Agents - pharmacology; Anticarcinogenic Agents - therapeutic use; basal diet; Biological and medical sciences; Butylene Glycols - pharmacology; Butylene Glycols - therapeutic use; Carcinogenesis, carcinogens and anticarcinogens; Dose-Response Relationship, Drug; Estradiol - blood; Estrogens; Estrus - drug effects; Female; Flax - chemistry; flaxseed; flaxseed oil; Foods and miscellaneous; Lactation - drug effects; Lignans - pharmacology; Lignans - therapeutic use; linoleic acid; Linseed Oil - pharmacology; Linseed Oil - therapeutic use; Mammary Glands, Animal - cytology; Mammary Glands, Animal - drug effects; Mammary Neoplasms, Experimental - prevention & control; Medical sciences; Neoplasms, Hormone-Dependent - prevention & control; Organ Size - drug effects; Ovary - drug effects; PND; post-natal day; Pregnancy; Rats; Rats, Sprague-Dawley; SDG; secoisolariciresinol diglycoside; Sexual Maturation - drug effects; TEB; terminal end bud; Tumors; α-linolenic acid; Lactation; Rat; Rodentia; Estrogen; Linseed; Anticarcinogen; Biological activity; Precocious puberty; Pregnancy; Tissue; Vertebrata; Mammalia; Animal; Plant origin; Lignan; Developmental stage; Estrous cycle; Mammary gland; Differentiation; Mechanism of action
• ISSN: 0143-3334; 1460-2180
• DOI: 10.1093/carcin/20.9.1831

Reduction of the highly proliferative terminal end bud (TEB) structures in the developing mammary gland by differentiation to alveolar buds (ABs) and lobules has been suggested to be protective against mammary cancer. Flaxseed is high in α-linolenic acid (ALA) and secoisolariciresinol diglycoside (SDG). SDG is the precursor of mammalian lignans, which can affect mammary gland structures. Thus, the objective of this study was to determine the effect of lifetime, gestation and lactation or after-weaning exposure to 5 or 10% flaxseed or SDG and flaxseed oil components on the mammary gland structures of virgin female rat offspring at post-natal day 50. Lifetime or gestation and lactation exposure to flaxseed altered mammary gland structure development, whereas exposure to flaxseed after weaning had no effect. Lifetime or gestation and lactation exposure to 5% flaxseed caused endocrine changes, as suggested by delayed puberty onset and reduced number of estrous cycles. These changes reduced exposure to endogenous estrogens, leading to atrophy of mammary TEB structures. SDG, but not flaxseed oil, at the level found in 5% flaxseed produced similar effects as 5% flaxseed. This suggested that the lignans were the component in flaxseed responsible for the observed effects. Lifetime or gestation and lactation exposure to 10% flaxseed also caused endocrine changes, as suggested by early puberty onset and lengthened cycles due to prolonged estrus. This increased exposure to endogenous estrogens and stimulated mammary gland differentiation, as indicated by fewer TEBs and more ABs. Thus, lifetime or gestation and lactation exposure to 5 or 10% flaxseed induced structural changes in the mammary gland that may potentially reduce mammary cancer risk.