title: Presence of insulin-like growth factor-I receptors and absence of growth hormone receptors in the antler tip.
abstract: Red deer antler tips in the growing phase were removed 60 days after the recommencement of growth for autoradiographical studies and RRAs. Sections were incubated with radiolabeled GH or insulin-like growth factor-I (IGF-I), with or without excess competing unlabeled hormones, and were analyzed autoradiographically. There was negligible binding of [125I]GH in any histological zone of antler sections. [125I]IGF-I showed highest specific binding in the chondroblast zone to a receptor demonstrating binding characteristics of the type 1 IGF receptor. The lowest specific binding of [125I]IGF-I was to prechondroblasts. RRAs on antler microsomal membrane preparations RRAs on antler microsomal membrane preparations confirmed the absence of GH receptors and the presence of type 1 IGF receptors found by autoradiography. These findings suggest that IGF-I may act in an endocrine manner in antler growth through a receptor resembling the type 1 IGF receptor. The presence of type 1 receptors in the chondroblast zone implicates IGF-I involvement in cartilage formation through matrixogenesis. There is no support for IGF-I having a major role in mitosis in the antler.
authors.affiliation: Ruakura Agricultural Centre, Ministry of Agriculture and Fisheries, Hamilton, New Zealand.
authors.forename: J L
authors.initials: JL
authors.lastname: Elliott
authors.forename: J M
authors.initials: JM
authors.lastname: Oldham
authors.forename: G R
authors.initials: GR
authors.lastname: Ambler
authors.forename: J J
authors.initials: JJ
authors.lastname: Bass
authors.forename: G S
authors.initials: GS
authors.lastname: Spencer
authors.forename: S C
authors.initials: SC
authors.lastname: Hodgkinson
authors.forename: B H
authors.initials: BH
authors.lastname: Breier
authors.forename: P D
authors.initials: PD
authors.lastname: Gluckman
authors.forename: J M
authors.initials: JM
authors.lastname: Suttie
mesh_terms: D000818:Animals; D000999:Antlers / Q000166:cytology / Q000378:metabolism*; D001345:Autoradiography; D001667:Binding, Competitive; D003670:Deer / Q000378:metabolism*; D007334:Insulin-Like Growth Factor I / Q000378:metabolism*; D007425:Intracellular Membranes / Q000378:metabolism; D007457:Iodine Radioisotopes; D007700:Kinetics; D008297:Male; D008861:Microsomes / Q000378:metabolism; D011956:Receptors, Cell Surface / Q000378:metabolism*; D017451:Receptors, Somatomedin; D011986:Receptors, Somatotropin / Q000032:analysis*
chemical_list: D007457:Iodine Radioisotopes; D011956:Receptors, Cell Surface; D017451:Receptors, Somatomedin; D011986:Receptors, Somatotropin; D007334:Insulin-Like Growth Factor I