Unsaturated Fatty Acids Esterified in 2‐Acyl‐1‐Lysophosphatidylcholine Bound to Albumin Are More Efficiently Taken up by the Young Rat Brain than the Unesterified Form

Abstract

The aim of the present study was to investigate whether unsaturated 2‐acyl‐lysophosphatidylcholine bound to plasma albumin is a relevant delivery form of unsaturated fatty acids to the developing brain. Twenty‐day‐old rats were perfused for 30 s with labeled palmitic, oleic, linoleic, and arachidonic acids in either their unesterified form or esterified in 2‐acyl‐lysophosphatidylcholine labeled on the choline and fatty acid moieties. Both forms were bound to albumin. Incorporation in brain lipid classes was followed within 1 h. The brain uptake of the unesterified fatty acids reached a plateau at 5–155 mim and was maximal for arachidonic acid (0.45% of the perfused dose). The brain uptake of palmitoyl‐lysophosphatidylcholine was similar to that of palmitic acid, whereas that of other lysophosphatidylcholines increased with the degree of unsaturation (rate and maximal uptake) and was six‐ to 10‐fold higher than that of the corresponding unesterified fatty acid. 2‐Acyl‐lysophosphatidylcholines were taken up without prior hydrolysis and reacylated into doubly labeled phosphatidylcholine, which was the most labeled lipid class, whereas lipid distribution of the unesterified fatty acid was more diversi fied. Partial hydrolysis of 2‐acyl‐lysophosphatidylcholine occurred in the brain tissue, and redistribution of the fatty acyl moiety into other phospholipid classes was also observed and was the highest for arachidonic acid. In this case, the percentage of esterification of this fatty acid in phosphatidylinositol (expressed as a percentage of the total lipid fraction) was relatively lower than that observed when the unesterified form was used. 1‐Acyl‐lysophosphatidylcholine (palmitoyl) was taken at the same extent that 2‐acyllysophosphatidylcholine but was more hydrolyzed and reesterified in other lipid classes than 2‐acyl isomer. All these results suggest that 2‐acyl‐lysophosphatidylcholine bound to albumin could be an efficient delivery form of unsaturated fatty acids to the developing rat brain and that the fatty acid delivery form could modulate their fate in the tissue.