J Korean Soc Endocrinol.  1997 Sep;12(3):376-385.

Characteristics of Serum Insulin-like Growth Factor ( IGF ) and IGF-Bindign Protein-3 during Pregnancy

• Lee DY
• Kim JS
• Lee HR
• Rhee CH
• Cho SC

Abstract

BACKGROUND
Pregnancy in human and rodents is associated with dramatic matemal metabolic changes. Insulin-like growth factors (IGFs) are mitogenic peptides that are essential for fetal and maternal tissue growth during pregnancy. They circulate complexed primarily with a serum IGF-binding protein (IGFBP-3) which regulates the availability of the IGFs to their specific target tissues.
METHODS
To examine the changes of IGFs and IGFB-3 during pregnancy, we measured serum total IGF-I, free IGF-I, IGF-II and IGFBP-3 by using specific radioimmunoassay, immunoradio-metric assay, western ligand blot and western immunoblot. Blood samples were obtained from 88 pregnant women between 6-40 weeks gestation.
RESULTS
While serum IGF-I levels increased up to 50% in late pregnancy, serum IGF-II levels remained unchanged. However, serum free IGF-I levels were significantly higher during pregnancy than in nonpregnancy. Western ligand blot analysis revealed that IGFBP-3 in pregnancy serum was significantly decreased at 6 weeks of gestation, continued decreased level until term, and returned to a nonpregnant level by postpartum 10 day. Serum IGFBP-3 profiles in Western immunoblot analysis revealed that 30 kDa fragments of IGFBP-3 were detectable in pregnancy serum but not in nonpregnancy serum. In contrast, serum IGFBP-3 levels using radioimmunoassay was significantly increased in late pregnancy.
CONCLUSIONS
1) serum IGF-I was significantly elevated in late pregnancy 2) serum IGF-II was not significantly changed 3) free IGF-I significantly elevated throughout gestation 4) intact IGFBP-3 was markedly reduced after 6 weeks of gestation.

MeSH Terms

Blotting, Western
Female
Humans
Insulin-Like Growth Factor Binding Protein 3
Insulin-Like Growth Factor I
Insulin-Like Growth Factor II
Peptides
Postpartum Period
Pregnancy*
Pregnant Women
Radioimmunoassay
Rodentia
Somatomedins
Insulin-Like Growth Factor Binding Protein 3
Insulin-Like Growth Factor I
Insulin-Like Growth Factor II
Peptides
Somatomedins