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Effect of maternal diabetes on phosphorylation of insulin‐like growth factor binding protein‐1 in cord serum
Author(s) -
Loukovaara M.,
Lein P.,
Teramo K.,
Nurminen E.,
Andersson S.,
Rutanen E.M.
Publication year - 2005
Publication title -
diabetic medicine
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.474
H-Index - 145
eISSN - 1464-5491
pISSN - 0742-3071
DOI - 10.1111/j.1464-5491.2005.01430.x
Subject(s) - medicine , gestational diabetes , cord blood , endocrinology , fetus , diabetes mellitus , insulin , cord , insulin like growth factor binding protein , pregnancy , gestational age , insulin like growth factor , growth factor , gestation , biology , receptor , surgery , genetics
Aims The insulin‐like growth factor (IGF) system is considered important in the regulation of fetal growth. Binding of IGFs to specific binding proteins (IGFBPs) modifies their actions. In fetal blood, IGFBP‐1 is the primary IGF binding protein whose phosphorylation generates proteins with different affinities for IGF‐I. We studied cord serum IGFBP‐1 phosphoisoform profiles in normal pregnancies and in diabetic pregnancies, which are frequently complicated by macrosomia. Research design and methods Cord serum IGFBP‐1 phosphoisoform concentrations were measured at birth by two immunoenzymometric assays in 67 pregnancies complicated by Type 1 diabetes, in 28 pregnancies complicated by insulin‐treated gestational diabetes, and in 62 normal pregnancies. Results Cord serum highly phosphorylated IGFBP‐1 (hpIGFBP‐1) concentrations were lower in pregnancies complicated by Type 1 diabetes (204 ± 36 µg/l, P = 0.032) and in pregnancies complicated by gestational diabetes (170 ± 28 µg/l, P = 0.031) than in controls (316 ± 34 µg/l). Cord serum lesser phosphorylated IGFBP‐1 (lpIGFBP‐1) concentrations were similar in diabetic and normal pregnancies ( P = 0.692 between groups by analysis of variance). Relative birth weight correlated negatively with cord serum hpIGFBP‐1 and lpIGFBP‐1 in diabetic pregnancies, and with cord serum lpIGFBP‐1 in normal pregnancies. Conclusions Maternal diabetes is associated with suppressed hpIGFBP‐1 but unaltered lpIGFBP‐1 concentrations in cord serum, suggesting that IGFBP‐1 phosphoisoforms are differentially regulated in the fetus. Because hpIGFBP‐1 has a higher affinity for IGF‐I than does lpIGFBP‐1, diabetes‐related changes in fetal IGFBP‐1 phosphorylation may increase IGF‐I bioavailability and, consequently, stimulate fetal growth. This may partly explain the increased occurrence of macrosomia in diabetic pregnancies.