title: Effect of dietary docosahexaenoic acid on biosynthesis of docosahexaenoic acid from alpha-linolenic acid in young rats.
abstract: Docosahexaenoic acid (DHA), a crucial nervous system n-3 PUFA, may be obtained in the diet or synthesized in vivo from dietary alpha-linolenic acid (LNA). We addressed whether DHA synthesis is regulated by the availability of dietary DHA in artificially reared rat pups, during p8 to p28 development. Over 20 days, one group of rat pups was continuously fed deuterium-labeled LNA (d5-LNA) and no other n-3 PUFA (d5-LNA diet), and a second group of rat pups was fed a d5-LNA diet with unlabeled DHA (d5-LNA + DHA diet). The rat pups were then euthanized, and the total amount of deuterium-labeled docosahexaenoic acid (d5-DHA) (synthesized DHA) as well as other n-3 fatty acids present in various body tissues, was quantified. In the d5-LNA + DHA group, the presence of dietary DHA led to a marked decrease (3- to 5-fold) in the total amount of d5-DHA that accumulated in all tissues that we examined, except in adipose. Overall, DHA accretion from d5-DHA was generally diminished by availability of dietary preformed DHA, inasmuch as this was found to be the predominant source of tissue DHA. When preformed DHA was unavailable, d5-DHA and unlabeled DHA were preferentially accreted in some tissues along with a net loss of unlabeled DHA from other organs.
authors.affiliation: Section of Nutritional Neurosciences, Laboratory of Membrane Biochemistry and Biophysics, National Institute on Alcohol Abuse and Alcoholism, National Institutes of Health, Bethesda, MD 20892, USA.
authors.forename: James C
authors.initials: JC
authors.lastname: DeMar
authors.forename: Carmine
authors.initials: C
authors.lastname: DiMartino
authors.forename: Adam W
authors.initials: AW
authors.lastname: Baca
authors.forename: William
authors.initials: W
authors.lastname: Lefkowitz
authors.forename: Norman
authors.initials: N
authors.lastname: Salem
mesh_terms: D000273:Adipose Tissue / Q000378:metabolism; D000818:Animals; D001823:Body Composition; D003903:Deuterium; D004041:Dietary Fats / Q000494:pharmacology*; D004281:Docosahexaenoic Acids / Q000378:metabolism* / Q000494:pharmacology*; D015118:Eicosapentaenoic Acid / Q000096:biosynthesis; D015525:Fatty Acids, Omega-3 / Q000096:biosynthesis*; D005231:Fatty Acids, Unsaturated / Q000096:biosynthesis; D008297:Male; D009929:Organ Size; D051381:Rats; D020318:Rats, Long-Evans; D017962:alpha-Linolenic Acid / Q000378:metabolism*
chemical_list: D004041:Dietary Fats; D015525:Fatty Acids, Omega-3; D005231:Fatty Acids, Unsaturated; D017962:alpha-Linolenic Acid; D004281:Docosahexaenoic Acids; D015118:Eicosapentaenoic Acid; D003903:Deuterium; C026219:docosapentaenoic acid