Inhibitors of choline uptake and metabolism cause developmental abnormalities in neurulating mouse embryos

Background: Choline is an essential nutrient in methylation, acetylcholine and phospholipid biosynthesis, and in cell signaling. The demand by an embryo or fetus for choline may place a pregnant woman and, subsequently, the developing conceptus at risk for choline deficiency. Methods: To determine whether a disruption in choline uptake and metabolism results in developmental abnormalities, early somite staged mouse embryos were exposed in vitro to either an inhibitor of choline uptake and metabolism, 2-dimethylaminoethanol (DMAE), or an inhibitor of phosphatidylcholine synthesis, 1-O-octadecyl-2-O-methyl-rac-glycero-3-phosphocholine (ET-18-OCH3). Cell death following inhibitor exposure was investigated with LysoTracker Red and histology. Results: Embryos exposed to 250-750 muM DMAE for 26 hr developed craniofacial hypoplasia and open neural tube defects in the forebrain, midbrain, and hindbrain regions. Embryos exposed to 125-275 muM ET-18-OCH3 exhibited similar defects or expansion of the brain vesicles. ET-18-OCH3-affected embryos also had a distended neural tube at the posterior neuropore. Embryonic growth was reduced in embryos treated with either DMAE (375, 500, and 750 muM) or ET-18-OCH3 (200 and 275 muM). Whole mount staining with LysoTracker Red and histological sections showed increased areas of cell death in embryos treated with 275 muM ET-18-OCH3 for 6 hr, but there was no evidence of cell death in DMAE-exposed embryos. Conclusions: Inhibition of choline uptake and metabolism during neurulation results in growth retardation and developmental defects that affect the neural tube and face. (C) 2001 Wiley-Liss Inc.