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Substrain‐specific cholesterol‐lowering effects of oats in mice: ‐ Clues for mechanism of action?
Author(s) -
Andersson Kristina,
Andersson Ulrika,
Xu Jie,
Swärd Karl,
Ahrné Siv,
Molin Göran,
Holm Cecilia,
Hellstrand Per
Publication year - 2012
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.26.1_supplement.969.7
Subject(s) - cholesterol 7 alpha hydroxylase , cholesterol , bile acid , excretion , medicine , bacteroides , endocrinology , chemistry , sterol , bran , avena , enzyme , biology , biochemistry , bacteria , agronomy , raw material , organic chemistry , genetics
Two substrains of C57BL/6 mice were recently shown to respond differently to oats with respect to changes in plasma cholesterol. By using this substrain difference we aimed to gain more knowledge about the mechanisms behind the cholesterol‐lowering effect of oats. Mice were fed an atherogenic diet supplemented with oat bran (27 %) or control fibers (cellulose). In C57BL/6NCrl mice plasma cholesterol was reduced by 15 %, the mRNA expression of the rate‐limiting enzyme for bile acid production, CYP7A1, was up‐regulated by fourfold, and the excretion of bile acids was increased by 40 %. In C57BL/6JBomTac mice there was no sustained reduction of plasma cholesterol, no increased excretion of bile acids, and CYP7A1 was down‐regulated with oat bran in the diet. The two substrains also differed regarding diversity and composition of intestinal microbiota. The C57BL/6NCrl mice had higher abundance of the bile acid de‐conjugating bacterial group of Bacteroides fragilis, which was negatively correlated to plasma cholesterol levels and positively correlated to CYP7A1 up‐regulation. No difference was found regarding glucose tolerance. Our findings provide evidence that the cholesterol‐lowering properties of oats involve increased production of bile acids with up‐regulation of CYP7A1. The effects of oats on bile acid excretion may be influenced by the composition of the intestinal microbiota.