Prostaglandins, Leukotrienes and Essential Fatty Acids
Volume 82, Issue 4 , Pages 273-276, April 2010

Quantitative contributions of diet and liver synthesis to docosahexaenoic acid homeostasis

Brain Physiology and Metabolism Section, National Institute on Aging, National Institutes of Health, 9000 Rockville Pike, Building 9, Room 1S128, Bethesda, MD 20892, USA

published online 15 March 2010.

Abstract 

Dietary requirements for maintaining brain and heart docosahexaenoic acid (DHA, 22:6n-3) homeostasis are not agreed on, in part because rates of liver DHA synthesis from circulating α-linolenic acid (α-LNA, 18:3n-3) have not been quantified. These rates can be estimated using intravenous radiotracer- or heavy isotope-labeled α-LNA infusion. In adult unanesthetized male rats, such infusion shows that liver synthesis–secretion rates of DHA from α-LNA markedly exceed brain and heart DHA synthesis rates and the brain DHA consumption rate, and that liver but not heart or brain synthesis is upregulated when dietary n-3 PUFA content is reduced. These rate differences reflect much higher expression of DHA-synthesizing enzymes in liver, and upregulation of liver but not heart or brain enzyme expression by reduced dietary n-3 PUFA content. A noninvasive intravenous [U−13C]α-LNA infusion method that produces steady-state liver tracer metabolism gives exact liver DHA synthesis–secretion rates and could be extended for human studies.

Abbreviations: DHA, docosahexaenoic acid, DPA, docosapentaenoic acid, EPA, eicosapentaenoic acid, α-LNA, α-linolenic acid, PUFA, polyunsaturated fatty acid

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PII: S0952-3278(10)00059-1

doi:10.1016/j.plefa.2010.02.015

Prostaglandins, Leukotrienes and Essential Fatty Acids
Volume 82, Issue 4 , Pages 273-276, April 2010