Ascorbic acid enables reversible dopamine receptor /sup 3/H-agonist binding

Journal Article · Mon Nov 16 04:00:00 EST 1981 · Life Sci.; (United States)

DOI:https://doi.org/10.1016/0024-3205(81)90665-2· OSTI ID:5800210

Leff, S; Sibley, D R; Hamblin, M; Creese, I

The effects of ascorbic acid on dopaminergic /sup 3/H-agonist receptor binding were studied in membrane homogenates of bovine anterior pituitary and caudate, and rat striatum. In all tissues virtually no stereospecific binding (defined using 1uM (+)butaclamol) of the /sup 3/H-agonists N-propylnorapomorphine (NPA), apomorphine, or dopamine could be demonstrated in the absence of ascorbic acid. Although levels of total /sup 3/H-agonist binding were three to five times greater in the absence than in the presence of 0.1% ascorbic acid, the increased binding was entirely non-stereospecific. Greater amounts of dopamine-inhibitable /sup 3/H-NPA binding could be demonstrated in the absence of 0.1% ascorbic acid, but this measure of ''specific binding'' was demonstrated not to represent dopamine receptor binding since several other catecholamines and catechol were equipotent with dopamine and more potent than the dopamine agonist (+/-)amino-6,7-dihydroxy-1,2,3,4-tetrahydronapthalene (ADTN) in inhibiting this binding. High levels of dopamine-displaceable /sup 3/H-agonist binding were detected in fresh and boiled homogenates of cerebellum, an area of brain which receives no dopaminergic innervation, further demonstrating the non-specific nature of /sup 3/H-agonist binding in the absence of ascorbic acid. These studies emphasize that under typical assay conditions ascorbic acid is required in order to demonstrate reversible and specific /sup 3/H-agonist binding to dopamine receptors.

• Research Organization: San Diego School of Medicine, La Jolla, CA
• OSTI ID: 5800210
• Journal Information: Life Sci.; (United States), Journal Name: Life Sci.; (United States) Vol. 29:20; ISSN LIFSA
• Country of Publication: United States
• Language: English

Related Subjects

550201* -- Biochemistry-- Tracer Techniques
59 BASIC BIOLOGICAL SCIENCES
AMINES
ANIMALS
AROMATICS
ASCORBIC ACID
AUTONOMIC NERVOUS SYSTEM AGENTS
CARDIOTONICS
CARDIOVASCULAR AGENTS
DOPAMINE
DRUGS
HYDROXY COMPOUNDS
ISOTOPE APPLICATIONS
LABELLED COMPOUNDS
LIGANDS
MAMMALS
NEUROREGULATORS
ORGANIC COMPOUNDS
PHENOLS
POLYPHENOLS
RATS
RECEPTORS
RESPONSE MODIFYING FACTORS
RODENTS
STEREOCHEMISTRY
SYMPATHOMIMETICS
TRACER TECHNIQUES
TRITIUM COMPOUNDS
UPTAKE
VERTEBRATES
VITAMINS