Absence of VLDL secretion does not affect alpha-tocopherol content in peripheral tissues.
alpha-Tocopherol is a lipid-soluble antioxidant that helps to prevent oxidative damage to cellular lipids. alpha-Tocopherol is absorbed by the intestine and is taken up and retained by the liver; it is widely presumed that alpha-tocopherol is then delivered to peripheral tissues by the secretion of VLDL. To determine whether VLDL secretion is truly important for the delivery of alpha-tocopherol to peripheral tissues, we examined alpha-tocopherol metabolism in mice that lack microsomal triglyceride transfer protein (Mttp) expression in the liver and therefore cannot secrete VLDL (Mttp(Delta/Delta) mice). Mttp(Delta/Delta) mice have low plasma lipid levels and increased stores of lipids in the liver. Similarly, alpha-tocopherol levels in the plasma were lower in Mttp(Delta/Delta) mice than in controls, whereas hepatic alpha-tocopherol stores were higher. However, alpha-tocopherol levels in the peripheral tissues of Mttp(Delta/Delta) mice were nearly identical to those of control mice, suggesting that VLDL secretion is not critical for the delivery of alpha-tocopherol to peripheral tissues. When fed a diet containing deuterated alpha-tocopherol, Mttp(Delta/Delta) and control mice had similar incorporation of deuterated alpha-tocopherol into plasma and various peripheral tissues. We conclude that the absence of VLDL secretion has little effect on the stores of alpha-tocopherol in peripheral tissues, at least in the mouse.
Minehira-Castelli
Kaori
K
Gladstone Institute of Cardiovascular Disease, University of California, San Francisco, 94158, USA.
Leonard
Scott W
SW
Walker
Quinn M
QM
Traber
Maret G
MG
Young
Stephen G
SG
D000818:Animals; D001055:Apolipoproteins B / Q000378:metabolism; D001692:Biological Transport; D002352:Carrier Proteins / Q000235:genetics / Q000378:metabolism; D003903:Deuterium; D050356:Lipid Metabolism / Q000502:physiology; D008055:Lipids / Q000097:blood; D008079:Lipoproteins, VLDL / Q000235:genetics / Q000378:metabolism / Q000502:physiology*; D008099:Liver / Q000378:metabolism; D051379:Mice; D008822:Mice, Transgenic; D014810:Vitamin E / Q000378:metabolism; D024502:alpha-Tocopherol / Q000378:metabolism*
D001055:Apolipoproteins B; D002352:Carrier Proteins; D008055:Lipids; D008079:Lipoproteins, VLDL; C106092:microsomal triglyceride transfer protein; D014810:Vitamin E; D003903:Deuterium; D024502:alpha-Tocopherol