title: Placenta as a link between amino acids, insulin-IGF axis, and low birth weight: evidence from twin studies.
abstract: Current evidence suggests that reduced placental transport of amino acids regulates fetal growth. We determined the association between fetal nutrition and the insulin-IGF axis by measuring the plasma concentrations of amino acids, insulin, IGF-I and IGF-binding protein-1 (IGFBP-1) in maternal and cord blood from gestational age-matched dichorionic (DC) twins with (n = 10) and without discordant birth weights (n = 10). In the growth-restricted (IUGR) twins, fetal concentrations of total essential (P < 0.01), nonessential (P < 0.01), and branched chain amino acids (P < 0.01) were lower than those in the appropriate for gestational age co-twins and concordant twin pairs. The IUGR twins had lower fetal concentrations of insulin (P < 0.001) and IGF-I (P < 0.05) and higher concentrations of IGFBP-1 (P < 0.01) than their appropriate for gestational age co-twins. In the discordant group, fetal IGFBP-1 had a negative association with fetal insulin (r = 0.71; P < 0.001), total essential amino acids (r = 0.78; P < 0.001), and branched chain amino acids (r = 0.64; P < 0.01). There was a positive correlation between total essential amino acids (r = 0.63; P < 0.001) and branched chain amino acids (r = 0.58; P < 0.01) and plasma insulin. However, there were no associations among fetal insulin, IGFBP-1 and nonessential amino acids. These data demonstrate the link between the reduction in certain essential and nonessential amino acids and alterations in fetal circulating levels of insulin and IGFBP-1, in growth-restricted twins.
authors.affiliation: University of Manchester, Academic Unit of Obstetrics and Gynecology, St. Mary's Hospital for Women and Children, Manchester, M13 OJH, United Kingdom. rbajoria@doctors.net.uk
authors.forename: Rekha
authors.initials: R
authors.lastname: Bajoria
authors.forename: Suren R
authors.initials: SR
authors.lastname: Sooranna
authors.forename: Stuart
authors.initials: S
authors.lastname: Ward
authors.forename: Maggie
authors.initials: M
authors.lastname: Hancock
mesh_terms: D000596:Amino Acids / Q000097:blood / Q000378:metabolism*; D000601:Amino Acids, Essential / Q000097:blood; D001692:Biological Transport; D001724:Birth Weight; D005260:Female; D005312:Fetal Blood; D005317:Fetal Growth Retardation / Q000097:blood; D005865:Gestational Age; D006801:Humans; D007230:Infant, Low Birth Weight / Q000378:metabolism*; D007231:Infant, Newborn; D007328:Insulin / Q000097:blood / Q000378:metabolism*; D018970:Insulin-Like Growth Factor Binding Protein 1 / Q000097:blood; D007334:Insulin-Like Growth Factor I / Q000032:analysis / Q000378:metabolism*; D010920:Placenta / Q000378:metabolism*; D014427:Twins
chemical_list: D000596:Amino Acids; D000601:Amino Acids, Essential; D007328:Insulin; D018970:Insulin-Like Growth Factor Binding Protein 1; D007334:Insulin-Like Growth Factor I