Investigación in vivo de la transferencia placentaria de ácidos grasos marcados por carbono 13 en humanos

Abstract

ABSTRACT Background: A supply of omega-3 long-chain polyunsaturated fatty acids (LC-PUFA) is essential for fetal development but mechanisms for their placental transfer are not well understood. Objective: We assessed distribution and placental transfer of 13C-labelled fatty acids (FA) 12 hours after oral application. Design: 11 pregnant women received 12h before elective caesarean section 0.5mg/kg 13C-palmitic acid (PA, 16:0), 0.5mg/kg 13C-oleic acid (OA, 18:1n-9), 0.5mg/kg 13C-linoleic acid (LA, 18:2n-6) and 0.1mg/kg 13C-docosahexaenoic acid (DHA, 22:6n-3) orally. Maternal blood samples were collected before tracer intake (-12h) and at -3,-2,-1, 0 and +1h relative to the time of caesarean. At birth, venous cord blood and placental tissue were collected and FA concentrations in individual lipid fractions and their tracer content (APE values) determined. Results: A relatively stable tracer enrichment was achieved in maternal lipid fractions 12h after tracer administration. Most 13C-PA and 13C-OA in maternal plasma were in triglycerides (TG), while 13C-LA and 13C-DHA were mainly found in both plasma phospholipids (PL) and TG. In placental tissue, 13C-FA were mainly in PL which comprised 80% of placental tissue lipids. Placenta/maternal plasma ratios and fetal/maternal plasma ratios for 13C-DHA were higher than for any other FA. Conclusions: 12 hours after oral application of 13C-labelled FA a relative stable tracer enrichment is achieved. We found a significantly higher ratio of 13C-DHA concentrations between cord plasma to maternal plasma than for the other studied fatty acids, which is in agreement with preferential transfer of DHA across the placenta. 13C-DHA is predominantly esterified into PL and TG of maternal plasma, which may facilitate its preferential placental uptake and transfer.