D5 dopamine receptors enhance Zn2+-sensitive GABA(A) currents in striatal cholinergic interneurons through a PKA/ PP1 cascade.
Cholinergic interneurons have been implicated in striatally mediated associative learning. In classical conditioning paradigms, conditioned stimuli trigger a transient suppression of neuronal activity that is dependent upon an intact dopaminergic innervation. Our hypothesis was that this suppression reflected dopaminergic enhancement of sensory-linked GABAergic input. As a test, the impact of dopamine on interneuronal GABA(A) receptor function was studied by combined patch-clamp recording and single-cell reverse transcription PCR. Activation of D5 dopamine receptors reversibly enhanced a Zn2+-sensitive component of GABA(A) currents. Although dependent upon protein kinase A (PKA) activation, the modulation was blocked by protein phosphatase 1 ( PP1) inhibition, suggesting it was dependent upon dephosphorylation. These results establish a novel mechanism by which intrastriatally released dopamine mediates changes in GABAergic signaling that could underlie the initial stages of associative learning.[1]References
- D5 dopamine receptors enhance Zn2+-sensitive GABA(A) currents in striatal cholinergic interneurons through a PKA/PP1 cascade. Yan, Z., Surmeier, D.J. Neuron (1997) [Pubmed]
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