Anandamide (N-arachidonoylethanolamide), a bioactive lipid, is reported to play a role in pregnancy maintenance and parturition. Our aims were to (1) evaluate AEA levels at the human maternal:fetal interface and (2) validate the use of solid-phase extraction of AEA from tissues. AEA was analyzed in cord and maternal blood, amniotic fluid, placenta, and fetal membranes collected during Caesarean section (n=14). Extraction efficiencies were 42 and 36% for the placenta and the fetal membranes, respectively. Tissue AEA was quantified using an isotope-dilution method and UPLC-ESI-MS/MS giving intra- and inter-day variability for tissues spiked with 0.2, 1, and 5pmol/g AEA of less than 12%. Accuracy for these spiked samples was between 95% and 103% for fetal membranes and between 99% and 114% for placenta. Mean AEA concentrations were 2.72 + or - 1.04 pmol/g for placenta and 1.19 + or - 0.68 pmol/g for fetal membranes, and 0.93 + or - 0.28, 0.88 + or - 0.33, 0.77 + or - 0.30, and 0.06 + or - 0.04nM for maternal, umbilical vein, and umbilical artery plasma and amniotic fluid. Higher AEA concentrations were found in placenta compared to fetal membranes (P<0.0001), in umbilical vein compared with umbilical artery (P=0.0015), and in plasma from maternal circulation compared with umbilical artery (P=0.0152). The relevance of these changes in AEA concentrations at the maternal:fetal interface requires further investigation.
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