Abstract
A G(i)-protein antibody AS/7 at 1:10 dilution significantly increased the K(d) values of the D2 agonist [3H]N-propylnorapomorphine (NPA) binding sites in the rat striatal membranes, and coincubation with sulphated cholecystokinin octapeptide (CCK-8; 1 nM) did not further increase the K(d) values. A GTP analogue guanylyl-imidodiphosphate (GMP-PNP) at 100 microM markedly increased the K(d) values of the [3H]NPA binding sites in the rat forebrain sections, and coincubation with CCK-8 (1 nM) again did not produce a further increase in the K(d) values. The present results indicate that abnormal activity of G-proteins abolished the ability of CCK-8 to reduce the D2 receptor affinity in the brain.
Publication types
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Research Support, Non-U.S. Gov't
MeSH terms
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Animals
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Apomorphine / analogs & derivatives
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Apomorphine / pharmacology
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Dopamine Agonists / pharmacology
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GTP-Binding Protein alpha Subunits, Gi-Go / metabolism
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GTP-Binding Protein alpha Subunits, Gi-Go / physiology
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GTP-Binding Proteins / antagonists & inhibitors
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GTP-Binding Proteins / physiology*
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Guanylyl Imidodiphosphate / pharmacology
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Male
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Membranes / drug effects
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Membranes / metabolism
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Neostriatum / drug effects
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Neostriatum / metabolism*
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Rats
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Rats, Sprague-Dawley
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Receptors, Dopamine D2 / drug effects
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Receptors, Dopamine D2 / metabolism*
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Sincalide / pharmacology*
Substances
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Dopamine Agonists
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Receptors, Dopamine D2
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Guanylyl Imidodiphosphate
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N-n-propylnorapomorphine
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GTP-Binding Proteins
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GTP-Binding Protein alpha Subunits, Gi-Go
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Sincalide
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Apomorphine