Placental 13C-DHA metabolism and relationship with maternal BMI, glycemia and birthweight.

BACKGROUND: Fetal docosahexaenoic acid (DHA) supply relies on preferential transplacental transfer, which is regulated by placental DHA lipid metabolism. Maternal hyperglycemia and obesity associate with higher birthweight and fetal DHA insufficiency but the role of placental DHA metabolism is unclear. METHODS: Explants from 17 term placenta were incubated with 13C-labeled DHA for 48 h, at 5 or 10 mmol/L glucose treatment, and the production of 17 individual newly synthesized 13C-DHA labeled lipids quantified by liquid chromatography mass spectrometry. RESULTS: Maternal BMI positively associated with 13C-DHA-labeled diacylglycerols, triacylglycerols, lysophospholipids, phosphatidylcholine and phosphatidylethanolamine plasmalogens, while maternal fasting glycemia positively associated with five 13C-DHA triacylglycerols. In turn, 13C-DHA-labeled phospholipids and triacylglycerols positively associated with birthweight centile. In-vitro glucose treatment increased most 13C-DHA-lipids, but decreased 13C-DHA phosphatidylethanolamine plasmalogens. However, with increasing maternal BMI, the magnitude of the glucose treatment induced increase in 13C-DHA phosphatidylcholine and 13C-DHA lysophospholipids was curtailed, with further decline in 13C-DHA phosphatidylethanolamine plasmalogens. Conversely, with increasing birthweight centile glucose treatment induced increases in 13C-DHA triacylglycerols were exaggerated, while glucose treatment induced decreases in 13C-DHA phosphatidylethanolamine plasmalogens were diminished. CONCLUSIONS: Maternal BMI and glycemia increased the production of different placental DHA lipids implying impact on different metabolic pathways. Glucose-induced elevation in placental DHA metabolism is moderated with higher maternal BMI. In turn, findings of associations between many DHA lipids with birthweight suggest that BMI and glycemia promote fetal growth partly through changes in placental DHA metabolism.

An enzymatic assay for quantification of inositol in human term placental tissue.

A modified sensitive, cheap and simple enzymatic assay method is described for the quantitation of inositol (6-carbon polyol) in human placental tissue. Water-soluble and total (water-soluble and lipid-bound) inositol isomers were extracted and quantified using a 96-well adaptation of the Megazyme® assay. This assay specifically recognized myo-inositol (predominant isomer), d-chiro-, epi-, and allo-inositols, but not scyllo-inositol, glucose or fucose. In term placenta, water-soluble and total inositol contents were high [489 (±58) and 635 (±69) µg/g respectively], and reliably quantified with good reproducibility. This modified assay could facilitate placental inositol biology research, particularly pertinent now with interest in myo-inositol supplementation for gestational diabetes (GDM) prevention.