Vitamin E in neural and visual function.
A rat model of vitamin E (alpha-tocopherol) deficiency with similar "clinical," electrophysiological, and neuropathological abnormalities to those seen in man was used to investigate the effects of various amounts and forms of alpha-tocopheryl acetate (alphaTA) on neural and visual function. Electrophysiological techniques provide an objective, non-invasive measure of neural and visual function. These techniques were used in the animal model to determine the minimum dietary requirement of vitamin E necessary to prevent neural and visual abnormalities. They were also used to compare the biological activities of the natural (RRR-) and synthetic (all-rac-) forms of alpha-tocopherol in neural tissues. The results were as follows: (1) Significant differences in neural and visual function were observed between deficient and control rats after approximately 8 months. (2) An intake of 1.0 mg/kg all-rac- or 0.75 mg/kg RRR-alphaTA was observed to marginally protect nerves from vitamin E deficiency. (3) The biological activity of all-rac-alpha-tocopherol in neural tissues was approximately 75% of RRR-alpha-tocopherol. (4) The concentration of free malondialdehyde (an indicator of lipid peroxidation) was significantly increased in tissues from the deficient compared to the control animals. These results are consistent with a deficiency of alpha-tocopherol causing increased lipid peroxidation leading to abnormal neural electrophysiology. They could also be explained by more specific but as yet undefined function(s) of alpha-tocopherol in neural tissues.
Hayton
S M
SM
Biochemistry, Endocrinology, and Metabolism Unit, Institute of Child Health, University College London, 30 Guilford Street, London WC1N 1EH, United Kingdom.
Muller
D P R
DP
D000818:Animals; D004032:Diet; D004596:Electroretinography; D005073:Evoked Potentials, Somatosensory; D005074:Evoked Potentials, Visual; D015227:Lipid Peroxidation; D008297:Male; D008315:Malondialdehyde / Q000032:analysis; D009422:Nervous System Diseases / Q000209:etiology* / Q000503:physiopathology / Q000517:prevention & control; D009751:Nutritional Requirements; D018384:Oxidative Stress; D051381:Rats; D017208:Rats, Wistar; D014786:Vision Disorders / Q000209:etiology* / Q000503:physiopathology / Q000517:prevention & control; D014810:Vitamin E / Q000008:administration & dosage* / Q000502:physiology*; D014811:Vitamin E Deficiency / Q000503:physiopathology*; D024502:alpha-Tocopherol / Q000008:administration & dosage / Q000032:analysis
D014810:Vitamin E; D008315:Malondialdehyde; D024502:alpha-Tocopherol