Effects of insulin on membrane lipid composition of human syncytiotrophoblast

CASTRO-PARODI MAURICIO; RECA ALEJANDRA; DIETRICH VALERIA; RODRIGUEZ CLARA; FERNANDEZ TOME; MARIA DEL CARMEN; DAMIANO ALICIA E

Adelaida

Congreso; International Federation of Placental Associations Meeting 2009; 2009

INTERNATIONAL FEDERATION OF PLACENTA ASSOCIATIONS

Altered placental membrane lipid composition in pregnancy may affect the fetal-maternal exchange. With gestational progress, the composition, structure and functions of these membrane lipid bilayers are modified in order to meet the changing metabolic needs of the growing fetus. Previously, we reported that plasma membranes of syncytiotrophoblast (hST) are unusual in comparison to other cell types. Because of the increase of sphingomyelin we also informed that preeclamptic hST is more rigid than normal hST. Since we observed high serum levels of insulin in preeclamptic women, we hypothesized that insulin may be implicated in the changes observed in preeclampic hST. The aim of this study was to evaluate if the insulin may alter the lipid composition of hST. Methods:Explants from normal term placentas were cultured with different concentrations of insulin during 24 h. The biochemical viability of the explants was determined by estimation of beta-hCG concentrations in the extracellular medium. Apical (MVM) and basal (BM) membrane vesicles were prepared by differential centrifugation. Lipid were extracted by Bligh-Dyer method and quantified by Fiske-Subarrow. Cholesterol was determined by enzymatic method.Insulin treatment produced no changes on the total phospholipid concentration in BM. On the contrary, showed an increase in total lipid content until reaching a constant value at 100 µUI/mL of insulin.There were no changes in the amount of cholesterol in both vesicles. Discussion: Our results suggest that insulin treatment only alter phospholipid concentration in MVM having no effect on BM vesicles. Further work is necessary to clarify the molecular mechanisms implicated in these changes and if they may play a role in the pathogenesis of preeclampsia.