Submitted on August 20, 2007
Revised on September 17, 2007
Accepted on September 17, 2007
Whole body distribution of deuterated linoleic and alpha-linolenic acids and their metabolites in the rat
Yu Hong Lin and Norman Salem . Jr
LMBB, NIAAA, NIH, Bethesda, MD 20892-9410
Corresponding Author: nsalem{at}niaaa.nih.gov
Little is known about the uptake or metabolism of essential fatty acids in various mammalian organs. Thus, the distribution of deuterated alpha-linolenic acid (18:3n-3) and linoleic acid (18:2n-6) and their metabolites was studied using a stable isotope tracer technique. Rats were orally administered a single dose of a mixture (20 mg each) of ethyl D5-18:3n-3 and D5-18:2n-6, and 25 tissues/animal were analyzed for D5-labeled PUFA at 4, 8, 24, 96, 168, 240, 360, 600 h after dosing. Plasma, stomach and spleen contained the highest concentrations of labeled precursors at the earliest time points while other internal organs and red blood cells reached their maximal concentration at 8 h. The time-course data was consistent with liver metabolism of EFAs, but local metabolism in other tissues could not be ruled out. Brain, spinal cord, heart, testes and eye accumulated docosahexaenoic acid with time, whereas skin accumulated mainly 20:4n-6. jlr On average, about 16-18% of the D5-18:3n-3 and D5-18:2n-6 initial dosage was eventually accumulated in tissues, principally in adipose, skin, and muscle. About 6.0% of D5-18:3n-3 and 2.6% of D5-18:2n-6 were elongated/desaturated and stored mainly in muscle, adipose and the carcass. The remaining 78% of both precursors was apparently catabolized or excreted.
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