The effects of different levels of all-rac- and RRR-alpha-tocopheryl acetate (vitamin E) on visual function in rats.
OBJECTIVE
A rat model of vitamin E (alpha-tocopherol) deficiency with similar "clinical", electrophysiological and neuropathological abnormalities to that seen in man was used to investigate the effects of various dietary intakes of synthetic (all-rac-) and natural (RRR-) alpha-tocopheryl acetate (alphaTA) on visual function.


METHODS
Longitudinal measurements of the electroretinogram (ERG) and visual evoked potentials (VEPs) were made monthly for 14 months in 9 groups of rats (n=12/group) receiving different amounts and types of alphaTA. The animals were then killed for biochemical analyses.


RESULTS
(1) The first significant abnormalities of both the ERG and VEP were found after 8 months of deficiency. (2) A diet containing 1.25 mg/kg of alphaTA provided marginal protection. (3) The biological activity of all-rac- was approximately 75% of RRR-alphaTA. (4) The concentration of free malondialdehyde (a measure of lipid peroxidation) was significantly increased in all tissues, including the eye, from deficient compared to control rats.


CONCLUSIONS
These results are consistent with alpha-tocopherol deficiency causing increased lipid peroxidation leading to abnormal visual function but could also be explained by more specific but undefined function(s) of alpha-tocopherol in the eye.
Biochemistry, Endocrinology and Metabolism Unit, Institute of Child Health, University College London, 30 Guilford Street, London WC1N 1EH, UK.
S M
SM
Hayton
A
A
Kriss
A
A
Wade
D P R
DP
Muller
D000818:Animals; D000975:Antioxidants / Q000494:pharmacology*; D004596:Electroretinography; D005074:Evoked Potentials, Visual / Q000187:drug effects*; D008297:Male; D008315:Malondialdehyde / Q000378:metabolism; D018384:Oxidative Stress / Q000187:drug effects; D051381:Rats; D017208:Rats, Wistar; D012160:Retina / Q000187:drug effects / Q000254:growth & development / Q000502:physiology; D014018:Tissue Distribution; D024505:Tocopherols; D014785:Vision, Ocular / Q000187:drug effects* / Q000502:physiology; D015430:Weight Gain; D024502:alpha-Tocopherol / Q000031:analogs & derivatives* / Q000494:pharmacology*
D000975:Antioxidants; D008315:Malondialdehyde; D024502:alpha-Tocopherol; D024505:Tocopherols