Linoleoyl-enriched triacylglycerol species increase in maternal liver during late pregnancy in the rat

In view of the previously reported changes in the fatty acid composition of maternal liver triacylglycerols in late pregnancy, changes in the composition of maternal liver triacylglycerol species were assessed in rats fed a semipurified diet during pregnancy. Between day 18 and day 21 of pregnancy, total maternal liver triacylglycerols increased by 50%. Triacylglycerol species with a total acyl carbon number (C) of 50 or 60 (C50, C60) remained unchanged while C48 and C52–C58 were relatively increased. The individual triacylglycerol species containing one, two or three linoleoyl moieties were incompletely recovered using a polar high temperature gas-liquid chromatography (GLC) column. Nevertheless, at day 21 compared to day 18, the linoleoyl-containing species were relatively increased by 62–463%, while tripalmitin was decreased by 38%. Our data suggest that despite an adequate intake of linoleic acid (25 g/kg in the diet), maternal hepatic triacylglycerol content of linoleic acid decreased during mid-pregnancy but increased significantly toward term possibly in preparation for the transfer of linoleic acid to the neonate during lactation.