Possible involvement of G-proteins in the regulation of striatal dopamine D2 receptor affinity by cholecystokinin octapeptide

Neurosci Lett. 1997 Jun 13;228(3):171-4. doi: 10.1016/s0304-3940(97)00392-3.

Abstract

A G(i)-protein antibody AS/7 at 1:10 dilution significantly increased the K(d) values of the D2 agonist [3H]N-propylnorapomorphine (NPA) binding sites in the rat striatal membranes, and coincubation with sulphated cholecystokinin octapeptide (CCK-8; 1 nM) did not further increase the K(d) values. A GTP analogue guanylyl-imidodiphosphate (GMP-PNP) at 100 microM markedly increased the K(d) values of the [3H]NPA binding sites in the rat forebrain sections, and coincubation with CCK-8 (1 nM) again did not produce a further increase in the K(d) values. The present results indicate that abnormal activity of G-proteins abolished the ability of CCK-8 to reduce the D2 receptor affinity in the brain.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Apomorphine / analogs & derivatives
  • Apomorphine / pharmacology
  • Dopamine Agonists / pharmacology
  • GTP-Binding Protein alpha Subunits, Gi-Go / metabolism
  • GTP-Binding Protein alpha Subunits, Gi-Go / physiology
  • GTP-Binding Proteins / antagonists & inhibitors
  • GTP-Binding Proteins / physiology*
  • Guanylyl Imidodiphosphate / pharmacology
  • Male
  • Membranes / drug effects
  • Membranes / metabolism
  • Neostriatum / drug effects
  • Neostriatum / metabolism*
  • Rats
  • Rats, Sprague-Dawley
  • Receptors, Dopamine D2 / drug effects
  • Receptors, Dopamine D2 / metabolism*
  • Sincalide / pharmacology*

Substances

  • Dopamine Agonists
  • Receptors, Dopamine D2
  • Guanylyl Imidodiphosphate
  • N-n-propylnorapomorphine
  • GTP-Binding Proteins
  • GTP-Binding Protein alpha Subunits, Gi-Go
  • Sincalide
  • Apomorphine