title: Insulin-like growth factors-I and -II and their binding proteins during postnatal development of dwarf Snell mice before and during growth hormone and thyroxine therapy.
abstract: The ontogeny of serum insulin-like growth factors (IGFs)-I and -II and their binding proteins (IGFBPs) was studied in normal and dwarf Snell mice. IGF-I concentrations in serum of normal mice increased between 4 and 8 weeks of age; dwarf mice had very low serum IGF-I levels. In both normals and dwarfs, serum IGF-II levels were highest soon after birth and dropped steadily thereafter. Western ligand blots of serum IGFBPs with 125I-IGF-II as tracer revealed the expected bands of 41.5, 38.5, 30-32 and 24 kDa. In normal mice the IGFBP-3 doublet was already detectable at 2 weeks of age, and its intensity increased with age. In dwarf mice the IGFBP-3 doublet was hardly detectable. The changes of IGFs and their IGFBPs were studied in sera of dwarf mice after treatment with growth hormone (GH) and/or thyroxine (T4) for 4 weeks. In spite of a comparable growth response obtained using these hormones, serum IGF-I was increased only by GH treatment; a small but significant decrease of serum IGF-II was obtained following GH or T4 treatment. An increase of the IGFBP-3 doublet was only obtained with GH; T4 and GH + T4 had no effect. The rise of IGFBP-3 after GH treatment was accompanied by the formation of the IGFBP 150 kDa complex, as measured by neutral gel chromatography. The size distribution of 125I-IGF-II was restored to normal, while with 125I-IGF-I only a small peak at 150 kDa was observed.(ABSTRACT TRUNCATED AT 250 WORDS)
authors.affiliation: Department of Paediatrics, Wilhelmina Children's Hospital, Utrecht University, The Netherlands.
authors.forename: S C
authors.initials: SC
authors.lastname: van Buul-Offers
authors.forename: R J
authors.initials: RJ
authors.lastname: Bloemen
authors.forename: M G
authors.initials: MG
authors.lastname: Reijnen-Gresnigt
authors.forename: H A
authors.initials: HA
authors.lastname: van Leiden
authors.forename: C M
authors.initials: CM
authors.lastname: Hoogerbrugge
authors.forename: J L
authors.initials: JL
authors.lastname: Van den Brande
mesh_terms: D000818:Animals; D001345:Autoradiography; D015153:Blotting, Western; D002352:Carrier Proteins / Q000378:metabolism*; D004392:Dwarfism / Q000378:metabolism*; D005260:Female; D013006:Growth Hormone / Q000494:pharmacology*; D006131:Growth Inhibitors / Q000378:metabolism*; D018969:Insulin-Like Growth Factor Binding Proteins; D007334:Insulin-Like Growth Factor I / Q000378:metabolism; D007335:Insulin-Like Growth Factor II / Q000378:metabolism; D008099:Liver / Q000378:metabolism; D008168:Lung / Q000378:metabolism; D008297:Male; D051379:Mice; D008817:Mice, Mutant Strains / Q000378:metabolism*; D009924:Organ Culture Techniques; D013002:Somatomedins / Q000378:metabolism*; D013974:Thyroxine / Q000494:pharmacology*
chemical_list: D002352:Carrier Proteins; D006131:Growth Inhibitors; D018969:Insulin-Like Growth Factor Binding Proteins; D013002:Somatomedins; D007334:Insulin-Like Growth Factor I; D007335:Insulin-Like Growth Factor II; D013006:Growth Hormone; D013974:Thyroxine