125I-Antisauvagine-30: a novel and specific high-affinity radioligand for the characterization of corticotropin-releasing factor type 2 receptors

• Published in: Neuropharmacology 2001, Vol.40 (1), p.114-122
• Main Authors: Higelin, Jacqueline, Py-Lang, Gabrielle, Paternoster, Cristina, Ellis, Gareth J, Patel, Arvind, Dautzenberg, Frank M
• Format: Article
• Language: English
• Subjects: Animals; Binding, Competitive - drug effects; Biological and medical sciences; Brain Chemistry - drug effects; Cell receptors; Cell structures and functions; Cells, Cultured; Corticotropin-Releasing Hormone - metabolism; Fundamental and applied biological sciences. Psychology; G protein-coupled receptor; Guanine Nucleotides - pharmacology; Hormone receptors. Growth factor receptors. Cytokine receptors. Prostaglandin receptors; Humans; In Vitro Techniques; Indicators and Reagents; Kinetics; Ligand binding; Ligand selectivity; Medical sciences; Membranes - drug effects; Membranes - metabolism; Molecular and cellular biology; Neuropharmacology; Neurotransmitters. Neurotransmission. Receptors; Peptide Fragments; Peptidergic system (neuropeptide, opioid peptide, opiates...). Adenosinergic and purinergic systems; Peptides - pharmacology; Pharmacology. Drug treatments; Radioligand Assay; Radiopharmaceuticals; Rats; Receptor expression; Receptors, Corticotropin-Releasing Hormone - drug effects; Xenopus
• ISSN: 0028-3908; 1873-7064
• DOI: 10.1016/S0028-3908(00)00105-2

Corticotropin-releasing factor (CRF) receptors type 1 (CRF 1) and type 2 (CRF 2) differ from each other in their pharmacological properties. The human and ovine CRF versions bind to CRF 1 receptors with significantly higher affinity than to CRF 2 receptors. Recently antisauvagine-30, an N-terminally truncated version of the CRF analog sauvagine, was characterized as a specific antagonist to mouse CRF 2B. We have synthesized the radiolabeled version 125I-antisauvagine-30 and tested it for its affinity at human CRF 1 (hCRF 1), hCRF 2A, Xenopus CRF 1 (xCRF 1) and xCRF 2 receptors. In control binding studies 125I-labeled hCRF, sauvagine and astressin were also bound to these receptors. 125I-antisauvagine-30 exclusively bound to hCRF 2A and xCRF 2 but not to hCRF 1 and xCRF 1 receptors. 125I-antisauvagine-30 binding to hCRF 2A and xCRF 2 receptors was saturable and of high affinity (hCRF 2A: K d=125 pM; xCRF 2: K d=1.1 nM). In displacement binding experiments using 125I-antisauvagine-30 as radioligand several CRF analogs bound to hCRF 2A and xCRF 2 receptors with similar rank orders as reported with other CRF radioligands. Finally, preliminary studies using 125I-antisauvagine-30 binding to membrane homogenates prepared from different rat brain structures showed that the peptide bound specifically to brain areas expressing CRF 2 receptors. These data demonstrate that 125I-antisauvagine-30 is the first high-affinity ligand to specifically label CRF 2 receptors.