The influence of PPARg on incorporation of fatty acids into placental lipid pools and their transfer to the fetus

Abstract

Alpha-linolenic acid (18:3n-3; ALA) and linoleic acid (18:2n-6;LA) are the two known essential fatty acids for humans. ALA and LA can be metabolized to more complex and more bioactive polyunsaturated fatty acids. In particular, ALA is the precursor of docosahexaenoic acid (22:6n-3; DHA). However, this conversion is limited at many stages of the life course and may not meet requirements. During pregnancy and lactation maternal intake of preformed DHA is thought to be important. Fetal and newborn needs for DHA must be met through placental transfer and maternal milk, respectively. Salmon is an oily fish that is rich inn-3 fatty acids including DHA. A study has shown that when increasing intake of salmon by pregnant women, increased the concentration of DHA in their blood during pregnancy and in their breast milk in early lactation. Based on the knowledge that fatty acids are endogenous agonists of all peroxisome proliferator-activated receptors (PPARs) and that PPAR³ interacts most efficiently with polyunsaturated fatty acids, this transcription factor has been suggested as a potential regulator of placental lipid (i.e. DHA) transfer by improving the expression of FATP for example. Objective: The purposes of the present study are to measure human placental lipid content(triglycerides, phospholipids, cholesterol esters and non-esterified fatty acids) and the fatty acid composition of these lipid pools and to determine the gene and protein expression of PPAR³ in order to better understand how lipid transfer occurs from the mother to the fetus and the role of PPAR³ participation in this process. Methods: Placenta samples from a subgroup of pregnant women involved in the Salmon in Pregnancy Study (control n=40 and salmon group n=40) will be analyzed. Fatty acid analysis of lipid extracts (triglycerides, phospholipids, cholesterol esters and non-esterified fatty acids) will be performed by gas chromatography. RNA and protein expression will be performed by real-time PCR and Western Blot analysis; PPAR-³ and other genes/proteins related to fatty acid transport will be examined. (AU)