Localization and Characterization of Insulin‐Like Growth Factor‐I Receptors in Rat Brain and Pituitary Gland Using in vitro Autoradiography and Computerized Densitometry A Distinct Distribution from Insulin Receptors

Abstract

In order to identify likely sites of action of insulin‐like growth factor‐I (IGF‐I) in rat brain and pituitary gland, we have used the technique of in vitro autoradiography and computerized densitometry to map, characterize and quantify its receptors in coronal and sagittal sections. A discrete and characteristic distribution of IGF‐I receptor binding was demonstrated, with specific binding representing 85% of total binding. Displacement and specificity competition curves in the olfactory bulb were typical for authentic IGF‐I receptors and computer analysis indicated a single class of binding site with a dissociation constant (Kd) of 13 nM for the choroid plexus and 5.1 nM for the olfactory ..