PREFERENTIAL INCORPORATION OF SN-2 LYSOPC DHA OVER UNESTERIFIED DHA IN THE YOUNG-RAT BRAIN

The uptake and metabolism of [H-3]docosahexaenoic acid (DHA) esterifie d at the sn-2 position of lysophosphatidylcholine (lysoPC DHA) and in the unesterified form, both bound to albumin, was studied in 20-day-ol d rats. LysoPC DHA was preferentially recovered in the brain (4-5% of the injected radioactivity) over the unesterified form of DHA (0.3-0.4 %). Conversely, the lysoPC form was taken up less than or at the same extent as the unesterified form by the Liver, heart, and kidney. In th e brain, DHA was mainly recovered in phosphatidylethanolamine whether the esterified or the unesterified form was used, although DHA from ly soPC was esterified at the same extent in phosphatidylcholine and phos phatidylethanolamine after 2.5 min. The uptake of labeled palmitic, ol eic, linoleic, and arachidonic acids, esterified or not in lysophospha tidylcholine, was also studied in brain, liver, heart, and kidney. Onl y the brain preferentially incorporated unsaturated (but not saturated ) lysoPC, with the uptake increasing with the degree of unsaturation o f the fatty acid moiety. These results strongly suggest that the young rat brain specifically utilizes albumin-lysoPC-containing polyunsatur ated fatty acids.