title: alpha-Linolenic acid does not contribute appreciably to docosahexaenoic acid within brain phospholipids of adult rats fed a diet enriched in docosahexaenoic acid.
abstract: Adult male unanesthetized rats, reared on a diet enriched in both alpha-linolenic acid (alpha-LNA) and docosahexaenoic acid (DHA), were infused intravenously for 5 min with [1-(14)C]alpha-LNA. Timed arterial samples were collected until the animals were killed at 5 min and the brain was removed after microwaving. Plasma and brain lipid concentrations and radioactivities were measured. Within plasma lipids, > 99% of radioactivity was in the form of unchanged [1-(14)C]alpha-LNA. Eighty-six per cent of brain radioactivity at 5 min was present as beta-oxidation products, whereas the remainder was mainly in 'stable' phospholipid or triglyceride as alpha-LNA or DHA. Equations derived from kinetic modeling demonstrated that unesterified unlabeled alpha-LNA rapidly enters brain from plasma, but that its incorporation into brain phospholipid and triglyceride, as in the form of synthesized DHA, is < or = 0.2% of the amount that enters the brain. Thus, in rats fed a diet containing large amounts of both alpha-LNA and DHA, the alpha-LNA that enters brain from plasma largely undergoes beta-oxidation, and is not an appreciable source of DHA within brain phospholipids.
authors.affiliation: Brain Physiology and Metabolism Section, National Institute on Aging, National Institutes of Health, Bethesda, Maryland 20892, USA.
authors.forename: James C
authors.initials: JC
authors.lastname: Demar
authors.forename: Kaizong
authors.initials: K
authors.lastname: Ma
authors.forename: Lisa
authors.initials: L
authors.lastname: Chang
authors.forename: Jane M
authors.initials: JM
authors.lastname: Bell
authors.forename: Stanley I
authors.initials: SI
authors.lastname: Rapoport
mesh_terms: D000818:Animals; D001921:Brain / Q000378:metabolism*; D004032:Diet; D004281:Docosahexaenoic Acids / Q000008:administration & dosage* / Q000378:metabolism*; D006706:Homeostasis; D007275:Injections, Intravenous; D050356:Lipid Metabolism; D008055:Lipids / Q000097:blood; D008297:Male; D009994:Osmolar Concentration; D010084:Oxidation-Reduction; D010743:Phospholipids / Q000378:metabolism*; D051381:Rats; D011916:Rats, Inbred F344; D014280:Triglycerides / Q000378:metabolism; D017962:alpha-Linolenic Acid / Q000008:administration & dosage* / Q000378:metabolism / Q000494:pharmacology
chemical_list: D008055:Lipids; D010743:Phospholipids; D014280:Triglycerides; D017962:alpha-Linolenic Acid; D004281:Docosahexaenoic Acids