alpha-Tocopherol concentrations of the nervous system and selected tissues of adult dogs fed three levels of vitamin E

The effects of dietary vitamin E levels on tissue α‐tocopherol (α−T) concentrations in different parts of the nervous system are largely unknown. Therefore, we measured the α−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 α−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 α−T concentrations, with the exception of the caudal colliculus, which retained 48%. Peripheral nerve α−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 α−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 α−T than most brain regions; in En dogs, they contained similar concentrations; but in −E dogs, they contained less α−T than most brain regions. Muscles and other tissues of −E dogs retained from 1 to 10% of En values. The studies demonstrate that the CNS conserved α−T compared to peripheral nerves and nonnervous tissues in adult dogs, but contained lower absolute concentrations of α−T compare with most other tissues.