Whole-body DHA synthesis-secretion kinetics from plasma eicosapentaenoic acid and alpha-linolenic acid in the free-living rat.
Whole body docosahexaenoic acid (DHA, 22:6n-3) synthesis from α-linolenic acid (ALA, 18:3n-3) is considered to be very low, however, the daily synthesis-secretion of DHA may be sufficient to supply the adult brain. The current study aims to assess whether whole body DHA synthesis-secretion kinetics are different when comparing plasma ALA versus eicosapentaenoic acid (EPA, 20:5n-3) as the precursor. Male Long Evans rats (n=6) were fed a 2% ALA in total fat diet for eight weeks, followed by surgery to implant a catheter into each of the jugular vein and carotid artery and 3h of steady-state infusion with a known amount of (2)H-ALA and (13)C-eicosapentaenoic acid (EPA, 20:5n3). Blood samples were collected at thirty-minute intervals and plasma enrichment of (2)H- and (13)C EPA, n-3 docosapentaenoic acid (DPAn-3, 22:5n-3) and DHA were determined for assessment of synthesis-secretion kinetic parameters. Results indicate a 13-fold higher synthesis-secretion coefficient for DHA from EPA as compared to ALA. However, after correcting for the 6.6 fold higher endogenous plasma ALA concentration, no significant differences in daily synthesis-secretion (nmol/day) of DHA (97.6±28.2 and 172±62), DPAn-3 (853±279 and 1139±484) or EPA (1587±592 and 1628±366) were observed from plasma unesterified ALA and EPA sources, respectively. These results suggest that typical diets which are significantly higher in ALA compared to EPA yield similar daily DHA synthesis-secretion despite a significantly higher synthesis-secretion coefficient from EPA.
Department of Nutritional Sciences, Faculty of Medicine, University of Toronto, 150 College St., Toronto, Ontario M5S 3E2, Canada. Electronic address: adam.metherel@utoronto.ca.
Adam H
AH
Metherel
Department of Nutritional Sciences, Faculty of Medicine, University of Toronto, 150 College St., Toronto, Ontario M5S 3E2, Canada.
Anthony F
AF
Domenichiello
Department of Nutritional Sciences, Faculty of Medicine, University of Toronto, 150 College St., Toronto, Ontario M5S 3E2, Canada.
Alex P
AP
Kitson
Department of Nutritional Sciences, Faculty of Medicine, University of Toronto, 150 College St., Toronto, Ontario M5S 3E2, Canada.
Kathryn E
KE
Hopperton
Department of Nutritional Sciences, Faculty of Medicine, University of Toronto, 150 College St., Toronto, Ontario M5S 3E2, Canada.
Richard P
RP
Bazinet
D000818:Animals; D004281:Docosahexaenoic Acids / Q000096:biosynthesis* / Q000235:genetics / Q000378:metabolism; D015118:Eicosapentaenoic Acid / Q000008:administration & dosage* / Q000378:metabolism; D007700:Kinetics; D008297:Male; D051381:Rats; D020318:Rats, Long-Evans; D017962:alpha-Linolenic Acid / Q000008:administration & dosage* / Q000378:metabolism
D017962:alpha-Linolenic Acid; D004281:Docosahexaenoic Acids; D015118:Eicosapentaenoic Acid
Lipids; Metabolism; Nutrition; Omega-3; Polyunsaturated fatty acid; Synthesis-secretion