Functional coupling of the human dopamine D3 receptor in a transfected NG 108-15 neuroblastoma-glioma hybrid cell line

Eur J Pharmacol. 1994 Jul 15;268(2):129-39. doi: 10.1016/0922-4106(94)90182-1.


Transfection of a human dopamine D3 receptor cDNA in a neuroblastoma-glioma hybrid cell line (NG 108-15) provided clonal cell lines stably expressing up to 600 fmol per mg protein of [125I]iodosulpiride binding sites. Dopamine and several agonists distinguished two receptor-affinity states in membranes. In the case of dopamine, the high-affinity state (Ki = 0.9 nM, 30% of total binding) was completely converted into a low-affinity state (Ki = 57 nM) in the presence of 10 microM guanosine-5'-O-(3-thiotriphosphate). In addition to these two sites, a site with a very low affinity for dopamine was evidenced in whole cells. The dopamine D3 receptor mediated two responses: c-fos activation, as measured by the appearance of Fos-like immunoreactivity, and increased mitogenesis, as measured by incorporation of [3H]thymidine. The Fos-like immunoreactivity appeared within 30 min, lasted 2 h and was blocked by the partially selective dopamine D3 receptor compound (+)-UH 232 (cis-(+)-5-methoxy-1-methyl-2-(di-n-propylamino)tetralin). The mitogenic effect, which occurred after a lag time (over 2 h stimulation), was produced with subnanomolar potency and full intrinsic activity by several compounds previously identified as dopamine D2 receptor agonists, e.g. quinpirole, (+)-7-OH-DPAT ((+)-7-hydroxy-2-(di-n-propylamino)tetralin) and RU 24926 (N-n-propyl-di-beta(3-hydroxyphenyl)-ethylamine), and was reversibly blocked by (+)-UH 232 (Ki = 9 nM). Talipexole (B-HT 920, 5-allyl-2-amino-5,6,7,8-tetrahydro-4H-thiazolo[4,5-d]azepin) was identified as a partial agonist at the dopamine D3 receptor. Dopamine D3 receptor-mediated mitogenesis was potentiated by a phorbol ester and was abolished by pretreatment with pertussis toxin. A mitogenic effect of same amplitude was elicited by bradykinin or carbachol, both acting through constitutive receptors. Bradykinin markedly activated inositol phosphate turnover, and had no effect on forskolin-stimulated cyclic AMP accumulation. Carbachol inhibited forskolin-stimulated cyclic AMP accumulation and had no effect on inositol-phosphate turnover. Quinpirole had no effect on any of these second messenger pathways. Thus, in transfected NG 108-15 cells, the dopamine D3 receptor is coupled to a pertussis toxin-sensitive G protein and mediates two possibly unrelated biological effects, through initial biochemical events that remain to be identified.

MeSH terms

  • Animals
  • Cyclic AMP / metabolism
  • Ergolines / pharmacology
  • GTP-Binding Proteins / physiology
  • Genes, fos
  • Glioma / pathology
  • Guanosine 5'-O-(3-Thiotriphosphate) / pharmacology
  • Humans
  • Hybrid Cells
  • Mice
  • Neuroblastoma / pathology
  • Quinpirole
  • Rats
  • Receptors, Dopamine / physiology*
  • Receptors, Dopamine D2*
  • Receptors, Dopamine D3
  • Sulpiride / metabolism
  • Thymidine / metabolism
  • Transfection
  • Tumor Cells, Cultured


  • DRD3 protein, human
  • Drd3 protein, mouse
  • Drd3 protein, rat
  • Ergolines
  • Receptors, Dopamine
  • Receptors, Dopamine D2
  • Receptors, Dopamine D3
  • Quinpirole
  • Guanosine 5'-O-(3-Thiotriphosphate)
  • Sulpiride
  • Cyclic AMP
  • GTP-Binding Proteins
  • Thymidine