Journal
AMERICAN JOURNAL OF PHYSIOLOGY-ENDOCRINOLOGY AND METABOLISM
Volume 292, Issue 2, Pages E476-E484Publisher
AMER PHYSIOLOGICAL SOC
DOI: 10.1152/ajpendo.00547.2005
Keywords
pregnancy; placenta; lipids; fetal growth
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Among other factors, fetal growth requires maternal supply of cholesterol. Cellular cholesterol uptake is mainly mediated by the LDL receptor (LDL-R) and the scavenger receptor family. We hypothesized that expression levels of key receptors of these families were regulated differently in placentas from IUGR pregnancies with varying degrees of severity. Third-trimester placentas from IUGR pregnancies with (IUGR-S) and without (IUGR-M) fetal hemodynamic changes and from control (AGA) pregnancies were studied. LDL-R, LDL-R-related protein (LRP-1), and scavenger receptor class B type I (SR-BI) mRNA and protein levels were measured. Cholesterol concentration and composition of lipoproteins were analyzed enzymatically and by lipid electrophoresis, respectively, in maternal and umbilical cord blood. LDL-R mRNA levels in IUGR- M were similar to AGA but lower ( P < 0.05) in IUGR- S. In contrast, LDL-R protein was twofold ( IUGR- M) and 1.8-fold ( IUGR- S) higher ( P < 0.05) than in the AGA group. LRP-1 mRNA and protein levels were not altered in the IUGR cases. SR-BI mRNA was unchanged in IUGR, but protein levels were lower ( P < 0.05) in IUGR- S than in the other groups. Maternal plasma concentrations of LDL cholesterol were higher ( P < 0.05) in the AGA group ( 188.5 +/- 23.6 mg/dl) than in the IUGR- S group (154.2 +/- 26.1). Electrophoretic mobility of the LDL fraction in maternal plasma demonstrated significant changes in migration toward higher values ( AGA 0.95 +/- 0.06, IUGR- M 1.12 +/- 0.11, P < 0.001; IUGR- S 1.28 +/- 0.20, P = 0.002). We conclude that LDL-R and SR-BI levels are altered in IUGR pregnancies. These differences were associated with changes in LDL, but not HDL, mobility and cholesterol concentration in maternal circulation.
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