Elsevier

Neuroscience

Volume 88, Issue 4, February 1999, Pages 1005-1008
Neuroscience

Letter to Neuroscience
Activation of dopamine D2 receptors decreases DARPP-32 phosphorylation in striatonigral and striatopallidal projection neurons via different mechanisms

https://doi.org/10.1016/S0306-4522(98)00411-4Get rights and content

Abstract

The vast majority of striatal neurons are GABAergic medium-sized spiny neurons. These cells receive glutamatergic input from the cortex, thalamus and limbic areas and dopaminergic input from the mesencephalon. Most relevant evidence indicates that dopamine D1 receptors are located on striatonigral projection neurons,5, 7 and that adenosine A2A receptors4, 12, 14 and most dopamine D2 receptors5, 7, 14 are located on striatopallidal projection neurons (see, however, 1, 13). Here we have utilized regulation of the phosphorylation of dopamine- and cyclic AMP-regulated phosphoprotein of mol. wt 32,000 (DARPP-32) to study the possible interactions among nigrostriatal dopaminergic neurons and the two classes of dopaminoceptive target neurons. We show that, in striatal slices, the D2 receptor agonist, quinpirole, strongly inhibits the phosphorylation of DARPP-32 induced by either the D1 receptor agonist, SKF 81297, or the A2A receptor agonist, CGS 21680. Tetrodotoxin abolished the effect of quinpirole on the D1 agonist-induced but not the A2A agonist-induced phosphorylation of DARPP-32. These data indicate that: (i) adenosine A2A and dopamine D2 receptors interact within the same striatopallidal neurons, and (ii) D2 receptors present on the striatopallidal neurons modulate the effects of D1 receptors on the striatonigral neurons. Thus, a single neurotransmitter is capable of activating distinct classes of receptors on distinct populations of target neurons, which, in turn, interact with each other through intercellular communication.

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Acknowledgements

This work was supported by U.S.P.H.S. grants MH40899 and DA10044 and by the Swedish Medical Research Council (project 11580).

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