Two intracellular signaling pathways for the dopamine D3 receptor: opposite and synergistic interactions with cyclic AMP

J Neurochem. 1997 Jan;68(1):1-9. doi: 10.1046/j.1471-4159.1997.68010001.x.


As cerebral neurons express the dopamine D1 receptor positively coupled with adenylyl cyclase, together with the D3 receptor, we have investigated in a heterologous cell expression system the relationships of cyclic AMP with D3 receptor signaling pathways. In NG108-15 cells transfected with the human D3 receptor cDNA, dopamine, quinpirole, and other dopamine receptor agonists inhibited cyclic AMP accumulation induced by forskolin. Quinpirole also increased mitogenesis, assessed by measuring [3H]thymidine incorporation. This effect was blocked partially by genistein, a tyrosine kinase inhibitor. Forskolin enhanced by 50-75% the quinpirole-induced [3H]thymidine incorporation. This effect was maximal with 100 nM forskolin, occurred after 6-16 h, was reproduced by cyclic AMP-permeable analogues, and was blocked by a protein kinase A inhibitor. Forskolin increased D3 receptor expression up to 135%, but only after 16 h and at concentrations of > 1 microM. Thus, in this cell line, the D3 receptor uses two distinct signaling pathways: it efficiently inhibits adenylyl cyclase and induces mitogenesis, an effect possibly involving tyrosine phosphorylation. Activation of the cyclic AMP cascade potentiates the D3 receptor-mediated mitogenic response, through phosphorylation by a cyclic AMP-dependent kinase of a yet unidentified component. Hence, transduction of the D3 receptor can involve both opposite and synergistic interactions with cyclic AMP.

MeSH terms

  • Cell Line
  • Colforsin / pharmacology
  • Cyclic AMP / physiology*
  • Dopamine Agonists / pharmacology
  • Enzyme Inhibitors / pharmacology
  • Genistein
  • Humans
  • Intracellular Membranes / physiology*
  • Isoflavones / pharmacology
  • Mitosis / drug effects
  • Protein-Tyrosine Kinases / antagonists & inhibitors
  • Quinpirole / pharmacology
  • Receptors, Dopamine D2 / metabolism*
  • Receptors, Dopamine D3
  • Signal Transduction*
  • Time Factors


  • DRD3 protein, human
  • Dopamine Agonists
  • Enzyme Inhibitors
  • Isoflavones
  • Receptors, Dopamine D2
  • Receptors, Dopamine D3
  • Colforsin
  • Quinpirole
  • Genistein
  • Cyclic AMP
  • Protein-Tyrosine Kinases