Abstract
Dopamine has been shown to stimulate phosphorylation of DARPP-32, a phosphoprotein highly enriched in medium-sized spiny neurons of the neostriatum. Here, we investigated the contribution of D1-like and D2-like dopamine receptors in the regulation of DARPP-32 phosphorylation in mouse striatal slices. D1-like and D2-like receptors had opposing effects on the state of DARPP-32 phosphorylation. The D1 receptor agonist SKF82526 increased DARPP-32 phosphorylation. In contrast, the D2 receptor agonist quinpirole decreased basal as well as D1 agonist-, forskolin-, and 8-bromo-cAMP-stimulated phosphorylation of DARPP-32. The ability of quinpirole to decrease D1-stimulated DARPP-32 phosphorylation was calcium-dependent and was blocked by the calcineurin inhibitor cyclosporin A, suggesting that the D2 effect involved an increase in intracellular calcium and activation of calcineurin. In support of this interpretation, Ca2+-free/EGTA medium induced a greater than 60-fold increase in DARPP-32 phosphorylation and abolished the ability of quinpirole to dephosphorylate DARPP-32. The antipsychotic drug raclopride, a selective D2 receptor antagonist, increased phosphorylation of DARPP-32 under basal conditions and in D2 agonist-treated slices. The results of this study demonstrate that dopamine exerts a bidirectional control on the state of phosphorylation of DARPP-32.
Publication types
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Comparative Study
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Research Support, U.S. Gov't, P.H.S.
MeSH terms
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8-Bromo Cyclic Adenosine Monophosphate / pharmacology
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Animals
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Antipsychotic Agents / pharmacology
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Calcineurin / metabolism
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Calcineurin Inhibitors
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Calcium / physiology
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Chelating Agents / pharmacology
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Colforsin / pharmacology
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Corpus Striatum / drug effects*
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Corpus Striatum / physiology
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Cyclosporine / pharmacology
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Dopamine / pharmacology*
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Dopamine Agonists / pharmacology
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Dopamine and cAMP-Regulated Phosphoprotein 32
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Egtazic Acid / pharmacology
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Fenoldopam / pharmacology
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Male
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Mice
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Mice, Inbred C57BL
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Nerve Tissue Proteins / metabolism*
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Neurotoxins / pharmacology
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Nucleus Accumbens / drug effects
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Nucleus Accumbens / physiology
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Phosphoproteins*
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Phosphorylation
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Protein Processing, Post-Translational / drug effects*
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Quinpirole / pharmacology
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Raclopride
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Receptors, Dopamine D1 / drug effects*
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Receptors, Dopamine D1 / physiology
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Receptors, Dopamine D2 / drug effects*
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Receptors, Dopamine D2 / physiology
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Receptors, N-Methyl-D-Aspartate / drug effects
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Receptors, N-Methyl-D-Aspartate / physiology
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Salicylamides / pharmacology
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Signal Transduction / drug effects*
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Tetrodotoxin / pharmacology
Substances
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Antipsychotic Agents
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Calcineurin Inhibitors
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Chelating Agents
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Dopamine Agonists
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Dopamine and cAMP-Regulated Phosphoprotein 32
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Nerve Tissue Proteins
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Neurotoxins
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Phosphoproteins
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Receptors, Dopamine D1
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Receptors, Dopamine D2
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Receptors, N-Methyl-D-Aspartate
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Salicylamides
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Colforsin
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Quinpirole
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8-Bromo Cyclic Adenosine Monophosphate
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Raclopride
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Tetrodotoxin
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Egtazic Acid
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Cyclosporine
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Calcineurin
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Fenoldopam
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Calcium
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Dopamine