Opposing patterns of signaling activation in dopamine D1 and D2 receptor-expressing striatal neurons in response to cocaine and haloperidol

J Neurosci. 2008 May 28;28(22):5671-85. doi: 10.1523/JNEUROSCI.1039-08.2008.


Psychostimulants and other drugs of abuse activate extracellular signal-regulated kinase (ERK) in the striatum, through combined stimulation of dopamine D(1) receptors (D1Rs) and glutamate NMDA receptors. Antipsychotic drugs activate similar signaling proteins in the striatum by blocking dopamine D(2) receptors (D2Rs). However, the neurons in which these pathways are activated by psychotropic drugs are not precisely identified. We used transgenic mice, in which enhanced green fluorescent protein (EGFP) expression was driven by D1R promoter (drd1a-EGFP) or D2R promoter (drd2-EGFP). We confirmed the expression of drd1a-EGFP in striatonigral and drd2-EGFP in striatopallidal neurons. Drd2-EGFP was also expressed in cholinergic interneurons, whereas no expression of either promoter was detected in GABAergic interneurons. Acute cocaine treatment increased phosphorylation of ERK and its direct or indirect nuclear targets, mitogen- and stress-activated kinase-1 (MSK1) and histone H3, exclusively in D1R-expressing output neurons in the dorsal striatum and nucleus accumbens. Cocaine-induced expression of c-Fos and Zif268 predominated in D1R-expressing neurons but was also observed in D2R-expressing neurons. One week after repeated cocaine administration, cocaine-induced signaling responses were decreased, with the exception of enhanced ERK phosphorylation in dorsal striatum. The responses remained confined to D1R neurons. In contrast, acute haloperidol injection activated phosphorylation of ERK, MSK1, and H3 only in D2R neurons and induced c-fos and zif268 predominantly in these neurons. Our results demonstrate that cocaine and haloperidol specifically activate signaling pathways in two completely segregated populations of striatal output neurons, providing direct evidence for the selective mechanisms by which these drugs exert their long-term effects.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Analysis of Variance
  • Animals
  • Cocaine / pharmacology*
  • Corpus Striatum / cytology*
  • Dopamine Antagonists / pharmacology*
  • Dopamine Uptake Inhibitors / pharmacology*
  • Dopamine and cAMP-Regulated Phosphoprotein 32 / metabolism
  • Enzyme Activation / drug effects
  • Extracellular Signal-Regulated MAP Kinases / metabolism
  • Gene Expression / drug effects
  • Gene Expression Regulation / drug effects
  • Genes, Immediate-Early / drug effects
  • Green Fluorescent Proteins / genetics
  • Green Fluorescent Proteins / metabolism
  • Haloperidol / pharmacology*
  • Histones / metabolism
  • Mice
  • Mice, Transgenic
  • Motor Activity / drug effects
  • Neurons / drug effects*
  • Receptors, Dopamine D1 / genetics
  • Receptors, Dopamine D1 / metabolism*
  • Receptors, Dopamine D2 / genetics
  • Receptors, Dopamine D2 / metabolism*
  • Ribosomal Protein S6 Kinases, 90-kDa / metabolism
  • Signal Transduction / drug effects
  • Time Factors


  • Dopamine Antagonists
  • Dopamine Uptake Inhibitors
  • Dopamine and cAMP-Regulated Phosphoprotein 32
  • Histones
  • Receptors, Dopamine D1
  • Receptors, Dopamine D2
  • dopamine D1A receptor
  • enhanced green fluorescent protein
  • Green Fluorescent Proteins
  • Ribosomal Protein S6 Kinases, 90-kDa
  • mitogen and stress-activated protein kinase 1
  • Extracellular Signal-Regulated MAP Kinases
  • Cocaine
  • Haloperidol