title: Dietary conjugated linoleic acid alters long chain polyunsaturated fatty acid metabolism in brain and liver of neonatal pigs.
abstract: Effects of dietary conjugated linoleic acid (CLA, 1% mixed isomers) on n-6 long-chain polyunsaturated fatty acid (LCPUFA) oxidation and biosynthesis were investigated in liver and brain tissues of neonatal piglets. Fatty acid β-oxidation was measured in tissue homogenates using [1-(14)C]linoleic acid (LA) and -arachidonic acid (ARA) substrates, while fatty acid desaturation and elongation were traced using [U-(13)C]LA and GC-MS. Dietary CLA had no effect on fatty acid β-oxidation, but significantly decreased n-6 LCPUFA biosynthesis by inhibition of LA elongation and desaturation. Differences were noted between our (13)C tracer assessment of desaturation/elongation and simple precursor-product indices computed from fatty acid composition data, indicating that caution should be exercised when employing the later. The inhibitory effects of CLA on elongation/desaturation were more pronounced in pigs fed a low fat diet (3% fat) than a high fat diet (25% fat). Direct elongation of linoleic acid to C20:2n-6 via the alternate elongation pathway might play an important role in n-6 LCPUFA synthesis because more than 40% of the synthetic products of [U-(13)C]LA accumulated in [(13)C]20:2n-6. Overall, the data show that dietary CLA shifted the distribution of the synthetic products of [U-(13)C]LA between elongation and desaturation in liver and decreased the total synthetic products of [U-(13)C]LA in brain by inhibiting LA elongation to C20:2n-6. The impact of CLA on brain LCPUFA metabolism of the developing neonate merits consideration and further investigation.
authors.affiliation: Laboratory of Developmental Nutrition, Department of Animal Science, North Carolina State University, Raleigh, NC 27695, USA.
authors.forename: Xi
authors.initials: X
authors.lastname: Lin
authors.forename: Jenny
authors.initials: J
authors.lastname: Bo
authors.forename: Susan A Mathews
authors.initials: SA
authors.lastname: Oliver
authors.forename: Benjamin A
authors.initials: BA
authors.lastname: Corl
authors.forename: Sheila K
authors.initials: SK
authors.lastname: Jacobi
authors.forename: William T
authors.initials: WT
authors.lastname: Oliver
authors.forename: Robert J
authors.initials: RJ
authors.lastname: Harrell
authors.forename: Jack
authors.initials: J
authors.lastname: Odle
mesh_terms: D000123:Acetyltransferases / Q000378:metabolism; D000818:Animals; D000831:Animals, Newborn; D016718:Arachidonic Acid / Q000378:metabolism; D001921:Brain / Q000378:metabolism*; D004041:Dietary Fats / Q000008:administration & dosage*; D044943:Fatty Acid Desaturases / Q000378:metabolism; D000081031:Fatty Acid Elongases; D005231:Fatty Acids, Unsaturated / Q000378:metabolism*; D019787:Linoleic Acid / Q000378:metabolism*; D044243:Linoleic Acids, Conjugated / Q000494:pharmacology*; D008099:Liver / Q000378:metabolism*; D013552:Swine
chemical_list: D004041:Dietary Fats; D005231:Fatty Acids, Unsaturated; D044243:Linoleic Acids, Conjugated; D016718:Arachidonic Acid; D019787:Linoleic Acid; D044943:Fatty Acid Desaturases; D000123:Acetyltransferases; D000081031:Fatty Acid Elongases