Mechanisms involved in vitamin E transport by primary enterocytes and in vivo absorption

J Lipid Res. 2007 Sep;48(9):2028-38. doi: 10.1194/jlr.M700207-JLR200. Epub 2007 Jun 20.

Abstract

It is generally believed that vitamin E is absorbed along with chylomicrons. However, we previously reported that human colon carcinoma Caco-2 cells use dual pathways, apolipoprotein B (apoB)-lipoproteins and HDLs, to transport vitamin E. Here, we used primary enterocytes and rodents to identify in vivo vitamin E absorption pathways. Uptake of [(3)H]alpha-tocopherol by primary rat and mouse enterocytes increased with time and reached a maximum at 1 h. In the absence of exogenous lipid supply, these cells secreted vitamin E with HDL. Lipids induced the secretion of vitamin E with intermediate density lipoproteins, and enterocytes supplemented with lipids and oleic acid secreted vitamin E with chylomicrons. The secretion of vitamin E with HDL was not affected by lipid supply but was enhanced when incubated with HDL. Microsomal triglyceride transfer protein inhibition reduced vitamin E secretion with chylomicrons without affecting its secretion with HDL. Enterocytes from Mttp-deficient mice also secreted less vitamin E with chylomicrons. In vivo absorption of [(3)H]alpha-tocopherol by mice after poloxamer 407 injection to inhibit lipoprotein lipase revealed that vitamin E was associated with triglyceride-rich lipoproteins and small HDLs containing apoB-48 and apoA-I. These studies indicate that enterocytes use two pathways for vitamin E absorption. Absorption with chylomicrons is the major pathway of vitamin E absorption. The HDL pathway may be important when chylomicron assembly is defective and can be exploited to deliver vitamin E without increasing fat consumption.

Publication types

  • Research Support, N.I.H., Extramural

MeSH terms

  • Animals
  • Bile Acids and Salts / physiology
  • Carrier Proteins / antagonists & inhibitors
  • Enterocytes / metabolism*
  • Intestinal Absorption / physiology*
  • Lipoproteins, HDL / physiology
  • Male
  • Mice
  • Mice, Inbred C57BL
  • Micelles
  • Oleic Acid / physiology
  • Rats
  • Rats, Sprague-Dawley
  • Vitamin E / metabolism*

Substances

  • Bile Acids and Salts
  • Carrier Proteins
  • Lipoproteins, HDL
  • Micelles
  • microsomal triglyceride transfer protein
  • Vitamin E
  • Oleic Acid