Incorporation of a phospholipid precursor into the hemochorionic and yolk sac placentas associated rat embryos

Pregnant Long-Evans rats were subjected to a teratogenic regimen, i.e., were fed a synthetic diet lacking folic acid and containing 9-methylpteroylglutamic acid on the 11th to 14th days of gestation. Experimental and control pregnant rats injected with 10 muCi of [2-14C] ethanolamine on the 14th day were killed 1 or 2 days later. The total radioactivity and radioactivities of phosphatidylethanolamine (PE), phosphatidylcholine (PC), and lysophosphatidylethanolamine (LPE) were determined in chloroform extracts of homogenates and subcellular fractions prepared from hemochorionic and yolk sac placentas and maternal liver. The distribution of radioisotope into PC and PE of control and experimental yolk sac placentas was similar, and paralleled the distribution in maternal liver. However, the distribution of radioisotope into PC and PE of the hemochorionic placentas did not parallel that of the maternal liver, and radiolabeled PC accumulated faster in experimental placentas than in controls. We suggest that the ability of the hemochorionic placenta to synthesize PC from PE was impaired by the teratogenic regimen, and that the organ took up relatively more PC from the maternal plasma. We propose that this teratogen-induced shift from placental lecithin synthesis to selective lecithin uptake underlies the previous finding of an increased accumulation of radio-labeled PC in embryos from pregnant females subjected to this teratogenic regimen (Chepenik and Waite, '73).