α‐tocopherol concentrations of the nervous system and selected tissues of adult dogs fed three levels of vitamin E

Abstract

The effects of dietary vitamin E levels on tissue alpha-tocopherol (alpha-T) concentrations in different parts of the nervous system are largely unknown. Therefore, we measured the alpha-T contents of nervous and other tissues obtained from beagle dogs fed for two years a vitamin E-deficient diet (-E, 0.05 +/- 0.02 mg vitamin E/kg diet, n = 2), a vitamin E-supplemented diet (+E, 114 +/- 14 mg/kg, n = 2), or a standard chow diet (En, 74 +/- 6 mg/kg, n = 3). Brain regions and spinal cords of +E dogs contained about double the alpha-T concentrations of En dogs, and about 10-fold those of -E dogs. The various brain regions of -E dogs, compared with En dogs, retained 12-18% of the alpha-T concentrations, with the exception of the caudal colliculus, which retained 48%. Peripheral nerve alpha-T concentrations in +E dogs (67 ng/mg wet weight) were nearly 5-fold higher than in En dogs (13.4 +/- 5.9 ng/mg) and 80-fold higher than in -E dogs (0.8 ng/mg). Within each dietary group, the lowest alpha-T concentrations in the central nervous system (CNS) were in the spinal cord. Peripheral nerves were the most susceptible to vitamin E repletion or depletion: in +E dogs, nerves contained higher concentrations of alpha-T than most brain regions; in En dogs, they contained similar concentrations; but in -E dogs, they contained less alpha-T than most brain regions. Muscles and other tissues of -E dogs retained from 1 to 10% of En values.(ABSTRACT TRUNCATED AT 250 WORDS)