α-Tocopherol Attenuates the Triglyceride- and Cholesterol-Lowering Effects of Rice Bran Tocotrienol in Rats Fed a Western Diet.
Previous studies demonstrated the ability of tocotrienol (T3) to lower levels of lipids, including cholesterol (Cho) and triglycerides (TG). Although α-tocopherol (α-Toc) reportedly inhibits the hypocholesterolemic effect of T3, there is no information about whether α-Toc influences the TG-lowering effect of T3 in vivo. In this study, we investigated the influence of α-Toc on the antihyperlipidemic effects (Cho- and TG-lowering) of rice bran tocotrienols (RBT3) in F344 rats fed a western diet. α-Toc attenuated both the Cho- and TG-lowering effects of RBT3 in vivo, whereas α-Toc alone exhibited no hypolipidemic effects. RBT3-induced Cpt-1a and Cyp7a1 gene expression was reduced by α-Toc. Furthermore, coadministration of α-Toc decreased liver and adipose tissue concentrations of tocotrienols in F344 rats. These results indicate that α-Toc has almost no antihyperlipidemic effect in vivo, but abrogates the antihyperlipidemic effect of RBT3 by reducing tissue concentrations of tocotrienols and regulating expression of genes involved in lipid metabolism. Understanding the underlying mechanism of the beneficial effects of T3 on lipid metabolism and the interaction with α-Toc will be important for developing T3-based therapeutics.
Food and Biodynamic Chemistry Laboratory, Graduate School of Agricultural Science, Tohoku University , Sendai 981-8555, Japan.
Akira
A
Shibata
Department of Nutritional Science, Faculty of Health and Welfare Science, Okayama Prefectural University , Okayama 719-1197, Japan.
Yuki
Y
Kawakami
Division of Food Function Research, Food Research Institute, NARO , Tsukuba, Ibaraki 305-8642, Japan.
Toshiyuki
T
Kimura
Food and Biotechnology Innovation Project, New Industry Creation Hatchery Center (NICHe), Tohoku University , Sendai 980-8579, Japan.|Food and Health Science Research Unit, Graduate School of Agricultural Science, Tohoku University , Sendai 981-8555, Japan.
Teruo
T
Miyazawa
Food and Biodynamic Chemistry Laboratory, Graduate School of Agricultural Science, Tohoku University , Sendai 981-8555, Japan.
Kiyotaka
K
Nakagawa
D000273:Adipose Tissue / Q000378:metabolism; D000818:Animals; D002334:Carnitine O-Palmitoyltransferase / Q000235:genetics / Q000378:metabolism; D002784:Cholesterol / Q000378:metabolism*; D066273:Diet, Western / Q000009:adverse effects; D050171:Dyslipidemias / Q000188:drug therapy* / Q000378:metabolism; D006801:Humans; D008099:Liver / Q000378:metabolism; D008297:Male; D012275:Oryza / Q000737:chemistry*; D010936:Plant Extracts / Q000008:administration & dosage*; D051381:Rats; D011916:Rats, Inbred F344; D024508:Tocotrienols / Q000008:administration & dosage*; D014280:Triglycerides / Q000378:metabolism*; D024502:alpha-Tocopherol / Q000008:administration & dosage*
D010936:Plant Extracts; D024508:Tocotrienols; D014280:Triglycerides; D002784:Cholesterol; D002334:Carnitine O-Palmitoyltransferase; C583748:carnitine palmitoyltransferase-1a, rat; D024502:alpha-Tocopherol
F344 rat; cholesterol; tocopherol; tocotrienol; triglyceride