title: Serum n-3 Tetracosapentaenoic Acid and Tetracosahexaenoic Acid Increase Following Higher Dietary α-Linolenic Acid but not Docosahexaenoic Acid.
abstract: n-3 Tetracosapentaenoic acid (24:5n-3, TPAn-3) and tetracosahexaenoic acid (24:6n-3, THA) are believed to be important intermediates to docosahexaenoic acid (DHA, 22:6n-3) synthesis. The purpose of this study is to report for the first time serum concentrations of TPAn-3 and THA and their response to changing dietary α-linolenic acid (18:3n-3, ALA) and DHA. The responses will then be used in an attempt to predict the location of these fatty acids in relation to DHA in the biosynthetic pathway. Male Long Evans rats (n = 6 per group) were fed either a low (0.1% of total fatty acids), medium (3%) or high (10%) ALA diet with no added DHA, or a low (0%), medium (0.2%) or high (2%) DHA diet with a background of 2% ALA for 8 weeks post-weaning. Serum n-3 and n-6 polyunsaturated fatty acid (PUFA) concentrations (nmol/mL ± SEM) were determined by gas chromatography-mass spectrometry. Serum THA increases from low (0.3 ± 0.1) to medium (5.8 ± 0.7) but not from medium to high (4.6 ± 0.9) dietary ALA, while serum TPAn-3 increases with increasing dietary ALA from 0.09 ± 0.04 to 0.70 ± 0.09 to 1.23 ± 0.14 nmol/mL. Following DHA feeding, neither TPAn-3 or THA change across all dietary DHA intake levels. Serum TPAn-3 demonstrates a similar response to dietary DHA. In conclusion, this is the first study to demonstrate that increases in dietary ALA but not DHA increase serum TPAn-3 and THA in rats, suggesting that both fatty acids are precursors to DHA in the biosynthetic pathway.
authors.affiliation: Department of Nutritional Sciences, Faculty of Medicine, University of Toronto, 150 College St., Room 307, Fitzgerald Building, Toronto, ON, M5S 3E2, Canada. adam.metherel@utoronto.ca.
authors.forename: Adam H
authors.initials: AH
authors.lastname: Metherel
authors.affiliation: Department of Nutritional Sciences, Faculty of Medicine, University of Toronto, 150 College St., Room 307, Fitzgerald Building, Toronto, ON, M5S 3E2, Canada.
authors.forename: Anthony F
authors.initials: AF
authors.lastname: Domenichiello
authors.affiliation: Department of Nutritional Sciences, Faculty of Medicine, University of Toronto, 150 College St., Room 307, Fitzgerald Building, Toronto, ON, M5S 3E2, Canada.
authors.forename: Alex P
authors.initials: AP
authors.lastname: Kitson
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, USA.
authors.forename: Yu-Hong
authors.initials: YH
authors.lastname: Lin
authors.affiliation: Department of Nutritional Sciences, Faculty of Medicine, University of Toronto, 150 College St., Room 307, Fitzgerald Building, Toronto, ON, M5S 3E2, Canada.
authors.forename: Richard P
authors.initials: RP
authors.lastname: Bazinet
mesh_terms: D000818:Animals; D053898:Biosynthetic Pathways / Q000187:drug effects; D004281:Docosahexaenoic Acids / Q000008:administration & dosage* / Q000097:blood; D008401:Gas Chromatography-Mass Spectrometry; D008297:Male; D051381:Rats; D020318:Rats, Long-Evans; D017962:alpha-Linolenic Acid / Q000008:administration & dosage*
chemical_list: D017962:alpha-Linolenic Acid; D004281:Docosahexaenoic Acids; C099831:tetracosahexaenoic acid; C099830:tetracosapentaenoic acid
keywords: Docosahexaenoic acid; Serum; Tetracosahexaenoic acid; n-3 Tetracosapentaenoic acid; α-Linolenic acid