Delivery and turnover of plasma-derived essential PUFAs in mammalian brain.
Polyunsaturated fatty acids (PUFAs) are critical to nervous system function and structure, but their rates of incorporation from plasma into brain have not been evaluated. In the adult rat, calculations based on our model show that at least 3;-5% of esterified brain arachidonic acid (AA) and 2;-8% of esterified brain docosahexaenoic acid (DHA) are replaced daily by unesterified PUFAs in plasma. These rates, when related to unlabeled brain PUFA composition, give half-lives of 1-2 weeks for plasma-brain exchange of AA and DHA. In the human brain, the arachidonate replacement rate is 0.3% per day. Although unesterified plasma PUFA concentrations are low, their rates of incorporation into brain are sufficient to compensate for metabolic and efflux losses, so that PUFA transport from plasma into brain as a component of a lipoprotein is unnecessary. Dietary supplementation, by altering plasma unesterified PUFA concentrations, can regulate brain PUFA content and may help to treat brain diseases involving PUFA imbalance.
Rapoport
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Brain Physiology and Metabolism Section, University of Iowa, Iowa City, IA 52242, USA. sir@helix.nih.gov
Chang
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Spector
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AA
D000818:Animals; D016718:Arachidonic Acid / Q000097:blood / Q000378:metabolism; D001921:Brain / Q000000981:diagnostic imaging / Q000378:metabolism*; D004042:Dietary Fats, Unsaturated; D004281:Docosahexaenoic Acids / Q000097:blood / Q000378:metabolism; D005231:Fatty Acids, Unsaturated / Q000008:administration & dosage / Q000097:blood / Q000737:chemistry / Q000378:metabolism*; D006801:Humans; D007700:Kinetics; D008297:Male; D008954:Models, Biological; D051381:Rats; D014055:Tomography, Emission-Computed
D004042:Dietary Fats, Unsaturated; D005231:Fatty Acids, Unsaturated; D004281:Docosahexaenoic Acids; D016718:Arachidonic Acid