Inhibition of [ 3H]quinpirole binding by a monoamine oxidase inhibitor in subcellular fractions of rat striatum

[ 3H]Quinpirole is a dopamine agonist with high affinity for D 2-like dopamine receptors. A number of non-dopaminergic compounds, most notably monoamine oxidase inhibitors (MAOIs), inhibit the binding of [ 3H]quinpirole, but not other D 2-like agonists and antagonists, in rat striatal membranes by a...

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Bibliographic Details
Published in:Life sciences (1973) 1998, Vol.63 (18), p.1643-1651
Main Authors: Levant, Beth, Bancroft, Gregory N.
Format: Article
Language:English
Subjects:
[ 3H]quinpirole
Animals
Binding, Competitive - drug effects
Dopamine Agonists - pharmacokinetics
In Vitro Techniques
Male
monoamine oxidase inhibitor
Monoamine Oxidase Inhibitors - pharmacology
Neostriatum - drug effects
Neostriatum - enzymology
Neostriatum - metabolism
Quinpirole - pharmacokinetics
Rats
Rats, Sprague-Dawley
Ribosomes - drug effects
Ribosomes - metabolism
Ro 41-1049
Spiperone - metabolism
striatum
Subcellular Fractions - drug effects
Subcellular Fractions - enzymology
Subcellular Fractions - metabolism
Synaptosomes - drug effects
Synaptosomes - metabolism
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Summary:[ 3H]Quinpirole is a dopamine agonist with high affinity for D 2-like dopamine receptors. A number of non-dopaminergic compounds, most notably monoamine oxidase inhibitors (MAOIs), inhibit the binding of [ 3H]quinpirole, but not other D 2-like agonists and antagonists, in rat striatal membranes by a mechanism that does not involve the enzymatic activity of MAO. To further characterize this novel interaction, the subcellular distribution of spiperone-displaceable, “D 2-like” [ 3H]quinpirole-labeled sites in rat striatum was assessed and compared with the distribution of MAOI-displaceable [ 3H]quinpirole binding (MQB). “D 2-like” [ 3H]quinpirole binding exhibited similar nanomolar affinity in the crude synaptosomal (P 2), crude microsomal (P 3), and ribosomal, post-microsomal (P 4) fractions. Total binding activity ( fmol bound fraction ) of “D 2-like” [ 3H]quinpirole binding was concentrated in the synaptosomal fraction (P 2B.) The subcellular distribution of MQB paralleled that of “D 2-like” [ 3H]quinpirole binding. This suggests that “D 2-like” [ 3H]quinpirole binding and MQB occur at a common membrane-bound binding site.
ISSN:0024-3205
1879-0631
DOI:10.1016/S0024-3205(98)00433-0