LIPOPROTEIN LIPASE (LPL) MRNA EXPRESSION IN PLACENTAS FROM NORMAL AND IUGR (INTRAUTERINE
GROWTH RESTRICTED) PREGNANCIES BY REAL-TIME PCR.
1S. Tabano,1G. Alvino,1P. Antonazzo,1V. Cozzi,1F. Grati,1M. Miozzo,
1I. Cetin.
1Dept. of Medicine, Surgery and Dentistry, University of Milano, Italy.
Introduction: Adequate placental transfer is necessary for normal intrauterine growth and development of the fetus. Intrauterine growth restriction (IUGR) is a condition associated with reduced nutritional placental supply. Recently, IUGR has been associated with changes in polyunsaturated fatty acid fetal-maternal relationships, mostly for the long chain polyunsaturated fatty acids, suggesting a role for these nutrients in the pathogenesis of IUGR. Lipoprotein lipase (LPL) plays a crucial role in lipoprotein and energy metabolism: it participates in the uptake of cholesterol-rich remnant particles, by acting as a ligand for VLDL receptor, LDL receptor, LDL-receptor related protein (LRP), and it is involved in the hydrolysis of triglycerides (TG) present in chylomicrons and very low- density lipoprotein (VLDL) to generate fatty acids, a source of energy for peripheral tissues. This suggests that the level of LPL expression in a given tissue is the rate limiting process for the uptake of triglyceride-derived fatty acids. LPL is expressed in human placenta, where it participates in the uptake of triglyceride-derived fatty acids.
Methods: We compared the expression levels of LPL, at the mRNA level, in placentas from 11 AGA (appropriate for gestational age) and 30 IUGR pregnancies at the time of Caesarean section. Relative Real-Time quantification of RNA extracted from placental villi was performed by the Ct method, using beta-actin as house-keeping, normaliser gene.
Results: No significant relationship was observed between LPL expression levels and gestational age in either AGA or IUGR pregnancies. Average values of LPL mRNA were higher in IUGR (104.44 ± 77.68 a.u.) than in AGA (21.14
± 10.09 a.u.) placentas, although not significantly. Moreover, a greater variability was observed in IUGR, with a sub-group of cases (40%) showing LPL mRNA expression over 60 a.u., a value never exceeded in normal cases.
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IUGR PREGNANCIES BY REAL-TIME PCR 209 Conclusions: The increased levels of lipoprotein lipase expression observed in this sub-group of IUGR pregnancies could represent a compensatory mechanism to increase placental fatty acid availability.
(Supported by an EU grant: PERILIP, contract nº QLRT-2001-00138).
Keywords: Intrauterine growth restriction – lipoprotein lipase – fatty acids – placental lipid metabolism – real-time PCR.
