α-Tocopherol status and expression of α-tocopherol transfer protein in type 2 diabetic Goto-Kakizaki rats

J Nutr Sci Vitaminol (Tokyo). 2013;59(1):64-8. doi: 10.3177/jnsv.59.64.

Abstract

Vitamin E, a critical fat-soluble vitamin antioxidant, is expressed on cell membranes and prevents propagation of lipid peroxidation. α-Tocopherol transfer protein (α-TTP) is a cytosolic protein located in the hepatocytes that acts as the principal regulator of the circulating α-tocopherol levels. Type 2 diabetes is a metabolic disorder characterized by hyperglycemia, caused by insulin resistance. Lipid peroxidation promotes the clinical progression and development of complications in type 2 diabetes. Results of animal and human experiments on the vitamin E status in diabetes are conflicting. The present study was conducted with the objective of investigating the vitamin E status and α-TTP expression in Goto-Kakizaki (GK) rats, a model of type 2 diabetes. In diabetic GK rats, increases of the α-tocopherol levels in the plasma and liver were observed as compared with the levels in the controls. No alternation in the CuZn-superoxide dismutase (SOD) or Mn-SOD gene expression was found in the liver of GK rats as compared with that in the controls. The GK rats showed an increase of the hepatic expression of the α-TTP gene as compared with the level in the controls. It can be suggested that the increased hepatic α-TTP gene expression levels may influence plasma α-tocopherol levels in the diabetic animals. Hence, investigation of the regulatory factors of α-TTP expression may provide important clues to highlighting the antioxidant mechanisms of vitamin E.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Antioxidants / metabolism*
  • Carrier Proteins / genetics
  • Carrier Proteins / metabolism*
  • Diabetes Mellitus, Type 2 / blood
  • Diabetes Mellitus, Type 2 / genetics
  • Diabetes Mellitus, Type 2 / metabolism*
  • Lipid Peroxidation*
  • Liver / metabolism*
  • Male
  • Nutritional Status
  • Rats
  • Rats, Inbred Strains
  • Rats, Wistar
  • Superoxide Dismutase / metabolism*
  • alpha-Tocopherol / blood*

Substances

  • Antioxidants
  • Carrier Proteins
  • alpha-tocopherol transfer protein
  • Superoxide Dismutase
  • alpha-Tocopherol