Functional coupling of GABA(B) receptors with G proteins that are sensitive to N-ethylmaleimide treatment, suramin, and benzalkonium chloride in rat cerebral cortical membranes

J Neural Transm (Vienna). 2000;107(10):1101-16. doi: 10.1007/s007020070024.

Abstract

Although it is known that GABA(B) receptors are negatively coupled to adenylyl cyclase, the detailed selectivity of functional interaction between GABA(B) receptors and Gi subfamily members is still ambiguous. (+/-)-Baclofen-stimulated high-affinity GTPase activity, which was competitively antagonized by 2-hydroxy-saclofen, was attenuated by pretreatment of the membranes with N-ethylmaleimide (NEM) in a concentration- and incubation period-dependent manner. The NEM-pretreated (50 microM, 15 min at 4 degrees C) membranes restored the (+/-)-baclofen-sensitive high-affinity GTPase activity when reconstituted with pertussis toxin-sensitive bovine brain G proteins. Among recombinant rat Galpha subunits, G(i alpha(-2)) appeared most effective as compared with other subunits (G(i alpha(-2)) > G(i alpha(-3) > G(i alpha(-1) = G(o alpha). The GABA(B) receptor-mediated high-affinity GTPase activity was also completely eliminated by 100 microM suramin and by 100 microM benzalkonium chloride. These results indicate that GABA(B) receptors in rat cerebral cortex couple to NEM-sensitive G proteins, in particular Gi2, which are sensitive to suramin and benzalkonium chloride.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adenylate Cyclase Toxin
  • Animals
  • Baclofen / analogs & derivatives*
  • Baclofen / pharmacology
  • Benzalkonium Compounds / pharmacology*
  • Cell Membrane / drug effects*
  • Cell Membrane / metabolism
  • Cell Membrane / ultrastructure
  • Cerebral Cortex / drug effects
  • Cerebral Cortex / metabolism
  • Cerebral Cortex / ultrastructure
  • Dose-Response Relationship, Drug
  • Ethylmaleimide / pharmacology*
  • GABA Antagonists / pharmacology
  • GTP Phosphohydrolases / drug effects
  • GTP Phosphohydrolases / metabolism
  • GTP-Binding Proteins / drug effects*
  • GTP-Binding Proteins / metabolism
  • Male
  • Neurons / drug effects
  • Neurons / metabolism
  • Neurons / ultrastructure
  • Pertussis Toxin
  • Rats
  • Rats, Sprague-Dawley
  • Receptors, GABA-B / drug effects*
  • Receptors, GABA-B / metabolism
  • Subcellular Fractions / drug effects*
  • Subcellular Fractions / metabolism
  • Subcellular Fractions / ultrastructure
  • Suramin / pharmacology*
  • Virulence Factors, Bordetella / metabolism

Substances

  • Adenylate Cyclase Toxin
  • Benzalkonium Compounds
  • GABA Antagonists
  • Receptors, GABA-B
  • Virulence Factors, Bordetella
  • Suramin
  • Pertussis Toxin
  • GTP Phosphohydrolases
  • GTP-Binding Proteins
  • Baclofen
  • saclofen
  • Ethylmaleimide