Ethanol consumption alters electroretinograms and depletes neural tissues of docosahexaenoic acid in rhesus monkeys: nutritional consequences of a low n-3 fatty acid diet.
BACKGROUND
Alcohol amblyopia is a rare neuropathy characterized by the development of blurred vision and a reduction in visual acuity. Further diagnostic details of this condition have shown abnormalities in the electroretinogram (ERG) that include an increase in implicit times in the a- and b-waves and a depression of b-wave amplitude.


METHODS
Periodically, the ERGs and the fatty acyl composition of nervous tissue were analyzed from alcohol-consuming rhesus monkeys (Macaca mulatta) (mean consumption 2.6 g kg/day over a 5-year period) and controls that were maintained on a nutritionally sufficient diet that had low, yet adequate, amounts of linoleic acid but very low alpha-linolenic acid.


RESULTS
Animals consuming alcohol had increased a- and b-wave implicit times and decreased b-wave amplitudes in their electroretinograms compared with those of the dietary control group at 2.5 and 5 years. The fatty acyl composition of brain specimens obtained by surgical biopsy at baseline, 2.5 years, and 5 years demonstrated that docosahexaenoic acid (DHA) had decreased in both groups of animals compared with baseline values. In the brains of the alcohol-treated animals, DHA was even further decreased (2.5 years: -20%; 5 years: -33%) compared with the diet controls. In the retinas of the alcohol-consuming animals at 5 years, there was a similar decrease in DHA (-35%) compared with controls. Generally, the n-6 fatty acid, docosapentaenoic acid (DPAn-6) increased in these tissues, apparently compensating for the loss of DHA.


CONCLUSIONS
A reciprocal change in the DHA/DPAn-6 ratio is known to be associated with abnormal electroretinograms in a number of species. Thus, a marginal intake of n-3 fatty acids in some alcohol abusers may, in part, be responsible for the biochemical changes that underlie the diminished retinal function associated with the visual abnormalities observed in alcohol-amblyopic patients.
Pawlosky
R J
RJ
Food Composition Laboratory, Beltsville Human Nutrition Research Center ARS, USDA, Beltsville, Maryland 20705, USA. pawlosky@bhnrc.usda.gov
Bacher
J
J
Salem
N
N
D000437:Alcoholism / Q000150:complications; D000824:Animal Nutritional Physiological Phenomena; D000818:Animals; D001921:Brain / Q000378:metabolism*; D001923:Brain Chemistry; D004281:Docosahexaenoic Acids / Q000378:metabolism*; D004596:Electroretinography; D000431:Ethanol / Q000008:administration & dosage*; D005227:Fatty Acids / Q000032:analysis; D015525:Fatty Acids, Omega-3 / Q000008:administration & dosage* / Q000502:physiology; D008253:Macaca mulatta; D008297:Male; D012160:Retina / Q000737:chemistry; D014786:Vision Disorders / Q000209:etiology
D005227:Fatty Acids; D015525:Fatty Acids, Omega-3; D004281:Docosahexaenoic Acids; D000431:Ethanol