Whole-body synthesis secretion of docosahexaenoic acid from circulating eicosapentaenoic acid in unanesthetized rats.
Dietary docosahexaenoic acid (DHA; 22:6n-3) and eicosapentaenoic acid (EPA; 20:5n-3) are considered important for maintaining normal heart and brain function, but little EPA is found in brain, and EPA cannot be elongated to DHA in rat heart due to the absence of elongase-2. Ingested EPA may have to be converted in the liver to DHA for it to be fully effective in brain and heart, but the rate of conversion is not agreed on. This rate was determined in male adult rats fed a standard n-3 PUFA, containing diet by infusing unesterified albumin-bound [U-(13)C]EPA intravenously for 2 h and measuring esterified [(13)C]labeled PUFAs in arterial plasma lipoproteins, as well as the specific activity of unesterified plasma EPA. Whole-body (presumably hepatic) synthesis secretion rates from circulating unesterified EPA, calculated from peak first derivatives of plasma esterified concentration x volume curves, equaled 2.61 micromol/day for docosapentaenoic acid (22:5n-3) and 5.46 micromol/day for DHA. The DHA synthesis rate was 24-fold greater than the reported brain DHA consumption rate in rats. Thus, dietary EPA could help to maintain brain and heart DHA homeostasis because it is converted at a relatively high rate in the liver to circulating DHA.
Gao
Fei
F
Brain Physiology and Metabolism Section, National Institute on Aging, National Institutes of Health, Bethesda, MD 20892, USA. gaof@mail.nih.gov
Kiesewetter
Dale
D
Chang
Lisa
L
Ma
Kaizong
K
Rapoport
Stanley I
SI
Igarashi
Miki
M
D000818:Animals; D004032:Diet; D004281:Docosahexaenoic Acids / Q000097:blood* / Q000378:metabolism*; D015118:Eicosapentaenoic Acid / Q000008:administration & dosage / Q000097:blood* / Q000378:metabolism*; D015525:Fatty Acids, Omega-3 / Q000008:administration & dosage / Q000097:blood; D006706:Homeostasis; D008297:Male; D051381:Rats; D011916:Rats, Inbred F344
D015525:Fatty Acids, Omega-3; D004281:Docosahexaenoic Acids; D015118:Eicosapentaenoic Acid