Distribution of arachidonic, eicosapentaenoic, docosahexaenoic and related fatty acids in ovine endometrial phospholipids in late gestation and labor

Abstract

The quantitative distribution of phospholipid (PL) fatty acids from ovine endometrial tissues taken at 105 ( n = 3) and 131 and 147 ( n = 5) days of gestation age (dGA) and in spontaneous labor (SL, n = 3) is reported. Phosphatidylcholine (PC), phosphatidylethanolamine (PE), phosphatidylinositol (PI), phosphatidylserine (PS), and lysophosphatidylcholine (LPC), were separated by thin layer chromatography (TLC) and analyzed for fatty acid composition by quantitative gas chromatography (GC). Saturates are found mainly in PS and PI and unsaturates predominantly in PC and PE. The major long-chain polyunsaturated fatty acids (LC-PUFA), arachidonic acid (AA), eicosapentaenoic acid (EPA), and docosahexaenoic acid (DHA), are found primarily in PC, PE, and PI. AA accumulates in PC, PI and PS ( p < 0.05) from late gestation to term and significantly declines in PC and PS ( p < 0.02) during labor, suggesting that ovine endometrium is a possible source of prostaglandin (PG) precursors. EPA decreases significantly from around 105 dGA to term and at labor in PC ( p < 0.02) and in PI ( p < 0.01), which may indicate the involvement of 3-series PGs in the regulation of uterine contraction. Unsaturation index (UI) and total PUFA increase from late gestation to term in PE ( p < 0.05) and decrease during labor ( p < 0.05). The ratios of n-6 n-3 PUFA increase in PI ( p < 0.05) and in PC ( p < 0.01) during labor mainly due to the decline of EPA in these PL. These data suggest that LC-PUFAs, precursors to PGs, are actively metabolized in late gestation and labor and that PC and PI may be important pools of the PG precursors during gestation and labor.