Biomaterial Database

Circulating levels of insulin, insulin-like growth factor-I (IGF-I), IGF-II, and IGF-binding proteins in the small for gestational age fetal rat. 1993

T G Unterman, and R A Simmons, and R P Glick, and E S Ogata

Department of Medicine, University of Illinois College of Medicine, Chicago.

Insulin-like growth factors (IGFs) are important regulators of somatic growth in childhood and circulate in association with specific binding proteins (IGFBPs). Insulin is important for the regulation of IGFs and IGFBPs in postnatal life and is required for normal growth in utero. We asked whether alterations in the availability of IGFs and/or their BPs may contribute to impaired fetal growth 24 h after bilateral uterine artery ligation when circulating levels of insulin are low and fetuses are small for gestational age (SGA). Bilateral uterine arterial ligation or sham surgery was performed on maternal rats on day 19 of gestation (term = 21.5 days). One day after ligation, fetuses were SGA compared to shams (2.9 +/- 0.1 vs. 3.5 +/- 0.1 g/fetus, respectively; P < 0.001), and liver weight was reduced (242 +/- 9 vs. 300 +/- 6 mg/liver; P < 0.001). Serum levels of both insulin and IGF-I were reduced approximately 50% in SGA litters compared to those in shams (P < 0.001) and correlated with each other (P < 0.02). IGF-I levels also correlated with fetal body and liver weights (P < 0.005 for each) even after controlling for the effects of insulin. Insulin levels correlated with body and liver weights (P < 0.02 and P < 0.03, respectively), but these relationships were not significant after controlling for the effects of IGF-I. Serum levels of IGF-II were not significantly reduced in SGA and did not correlate with fetal weight or insulin or IGF-I levels. [125I]IGF-I binding assay demonstrated that the availability of IGFBPs was increased in SGA serum, and Western ligand blotting indicated that circulating levels of 32K IGFBPs were increased in SGA fetuses compared to shams. Densitometric analysis indicated that levels of 32K IGFBPs were 4-fold greater in SGA litters (P < 0.001 vs. shams), and the level of 32K IGFBPs correlated with fetal body and liver weights (P < 0.05 for each) and with levels of both insulin and IGF-I (P < 0.001 for each), but not with levels of IGF-II. Immunoblotting with newly developed antiserum against rat IGFBP-1 confirmed that levels of immunoreactive 32K IGFBP-1 are increased in SGA serum, and immunoprecipitation studies confirmed that IGFBP-1 accounted for the rise in 32K IGFBPs in SGA serum.(ABSTRACT TRUNCATED AT 400 WORDS)

UI	MeSH Term	Description	Entries
D007328	Insulin	A 51-amino acid pancreatic hormone that plays a major role in the regulation of glucose metabolism, directly by suppressing endogenous glucose production (GLYCOGENOLYSIS; GLUCONEOGENESIS) and indirectly by suppressing GLUCAGON secretion and LIPOLYSIS. Native insulin is a globular protein comprised of a zinc-coordinated hexamer. Each insulin monomer containing two chains, A (21 residues) and B (30 residues), linked by two disulfide bonds. Insulin is used as a drug to control insulin-dependent diabetes mellitus (DIABETES MELLITUS, TYPE 1).	Iletin,Insulin A Chain,Insulin B Chain,Insulin, Regular,Novolin,Sodium Insulin,Soluble Insulin,Chain, Insulin B,Insulin, Sodium,Insulin, Soluble,Regular Insulin
D007334	Insulin-Like Growth Factor I	A well-characterized basic peptide believed to be secreted by the liver and to circulate in the blood. It has growth-regulating, insulin-like, and mitogenic activities. This growth factor has a major, but not absolute, dependence on GROWTH HORMONE. It is believed to be mainly active in adults in contrast to INSULIN-LIKE GROWTH FACTOR II, which is a major fetal growth factor.	IGF-I,Somatomedin C,IGF-1,IGF-I-SmC,Insulin Like Growth Factor I,Insulin-Like Somatomedin Peptide I,Insulin Like Somatomedin Peptide I
D007335	Insulin-Like Growth Factor II	A well-characterized neutral peptide believed to be secreted by the LIVER and to circulate in the BLOOD. It has growth-regulating, insulin-like and mitogenic activities. The growth factor has a major, but not absolute, dependence on SOMATOTROPIN. It is believed to be a major fetal growth factor in contrast to INSULIN-LIKE GROWTH FACTOR I, which is a major growth factor in adults.	IGF-II,Multiplication-Stimulating Activity,Somatomedin MSA,IGF-2,Insulin Like Growth Factor II,Insulin-Like Somatomedin Peptide II,Multiplication-Stimulating Factor,Somatomedin A,Factor, Multiplication-Stimulating,Insulin Like Somatomedin Peptide II,Multiplication Stimulating Activity,Multiplication Stimulating Factor
D008026	Ligation	Application of a ligature to tie a vessel or strangulate a part.	Ligature,Ligations,Ligatures
D008099	Liver	A large lobed glandular organ in the abdomen of vertebrates that is responsible for detoxification, metabolism, synthesis and storage of various substances.	Livers
D009929	Organ Size	The measurement of an organ in volume, mass, or heaviness.	Organ Volume,Organ Weight,Size, Organ,Weight, Organ
D001835	Body Weight	The mass or quantity of heaviness of an individual. It is expressed by units of pounds or kilograms.	Body Weights,Weight, Body,Weights, Body
D001921	Brain	The part of CENTRAL NERVOUS SYSTEM that is contained within the skull (CRANIUM). Arising from the NEURAL TUBE, the embryonic brain is comprised of three major parts including PROSENCEPHALON (the forebrain); MESENCEPHALON (the midbrain); and RHOMBENCEPHALON (the hindbrain). The developed brain consists of CEREBRUM; CEREBELLUM; and other structures in the BRAIN STEM.	Encephalon
D002352	Carrier Proteins	Proteins that bind or transport specific substances in the blood, within the cell, or across cell membranes.	Binding Proteins,Carrier Protein,Transport Protein,Transport Proteins,Binding Protein,Protein, Carrier,Proteins, Carrier
D005260	Female		Females