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Dietary arachidonic acid (20:4n-6) utilization in-vivo for carbon recycling into de-novo lipogenesis and conversion to n-6 long chain polyunsaturates was investigated in baboon neonates using [U-13C]20:4n-6. Neonates consuming a formula typical of human milk received a single oral dose of [13C]arachidonic acid in sn-2 position of either triglyceride or phosphatidylcholine at 18–19 days of postnatal life. Neonate brain, retina, liver, and plasma were obtained 10 days later (28–29 days of life). Low isotopic enrichment (0.27–1.0%Total label) was detected in dihomo-γ-linolenic acid (20:3n-6) in all tissues, but label incorporation into saturates or monounsaturates was not detected. In neonate brain and retina, 16% and 11% of total label was recovered in 22:4n-6, respectively. The relative contribution of dietary fatty acids to postnatal brain 22:4n-6 accretion can be estimated for dietary 20:4n-6 and preformed 22:4n-6 as 17% and 8%, respectively, corresponding to efficiencies of 0.48% and 0.54% of dietary levels, respectively. These results demonstrate in term baboon neonates that in vivo 1) 20:4n-6 was retroconverted to 20:3n-6, 2) 20:4n-6 did not contribute significantly to de novo lipogenesis of saturates and monounsaturates, and 3) the preformed 20:4n-6 contribution to brain 22:4n-6 accumulation was quantitatively a significant metabolic fate for dietary 20:4n-6.—Wijendran, V., P. Lawrence, G-Y. Diau, G. Boehm, P. W. Nathanielsz, and J. T. Brenna. Significant utilization of dietary arachidonic acid is for brain adrenic acid in baboon neonates. J. Lipid Res. 2002. 43: 762–767. |
