New type of tachykinin binding site in the rat brain characterized by specific binding of a labeled eledoisin derivative
A new ligand for investigating tachykinin-binding site subtypes was synthesized by coupling the /sup 125/I-Bolton and Hunter reagent to eledoisin (/sup 125/I-BHE). Using a synaptosomal preparation (P2 fraction) of rat cerebral cortex, /sup 125/I-BHE was shown to bind with apparent high affinity (apparent Kd . 15.3 nM). When concentrations of up to 30 nM /sup 125/I-BHE were used, /sup 125/I-BHE binding was specific, saturable, reversible, and temperature-dependent. In contrast to (/sup 3/H)dopamine, /sup 125/I-BHE was not taken up within synaptosomes by an ouabain-sensitive process. Eledoisin, kassinin, and substance P were examined for their ability to inhibit specific /sup 125/I-BHE binding to cortical synaptosomes. Eledoisin and kassinin were considerably more potent than substance P, in contrast to the order of potency observed for specific /sup 125/I-Bolton-Hunter substance P (/sup 125/I-BHSP) binding. Specific /sup 125/I-BHE binding was highest in the cerebral cortex and hypothalamus; intermediate in the hippocampus, striatum, and thalamus; low in the mesencephalon, septum, and substantia nigra; and absent in the cerebellum. Comparison of these data with those previously obtained for /sup 125/I-BHSP binding to synaptosomes indicated that /sup 125/I-BHE-labeled binding sites differ markedly from those of /sup 125/I-BHSP-labeled binding sites. Therefore, tachykinin receptors other than substance P receptors seem to be present in the central nervous system.
- Research Organization:
- College de France, Paris
- OSTI ID:
- 6001315
- Journal Information:
- Mol. Pharmacol.; (United States), Journal Name: Mol. Pharmacol.; (United States) Vol. 26:2; ISSN MOPMA
- Country of Publication:
- United States
- Language:
- English
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59 BASIC BIOLOGICAL SCIENCES
ANIMALS
BETA DECAY RADIOISOTOPES
BODY
BRAIN
CENTRAL NERVOUS SYSTEM
CHEMICAL BONDS
DAYS LIVING RADIOISOTOPES
ELECTRON CAPTURE RADIOISOTOPES
INTERMEDIATE MASS NUCLEI
IODINE 125
IODINE ISOTOPES
ISOTOPE APPLICATIONS
ISOTOPES
KININS
LABELLED COMPOUNDS
LIGANDS
MAMMALS
NERVOUS SYSTEM
NUCLEI
ODD-EVEN NUCLEI
ORGANIC COMPOUNDS
ORGANS
PEPTIDES
POLYPEPTIDES
PROTEINS
RADIOISOTOPES
RATS
RECEPTORS
RODENTS
TRACER TECHNIQUES
TRITIUM COMPOUNDS
VERTEBRATES