Characterization of receptor-mediated [35S]GTPgammaS binding to cortical membranes from postmortem human brain

Eur J Pharmacol. 2000 Feb 25;390(1-2):25-36. doi: 10.1016/s0014-2999(99)00827-4.


The [35S]GTPgammaS binding assay represents a functional approach to assess the coupling between receptors and G-proteins. The optimal conditions for [35S]GTPgammaS binding to human brain homogenates were established in postmortem samples of prefrontal cortex. The influence of protein content, incubation time, GDP, Mg(2+), and NaCl concentrations on the [35S]GTPgammaS binding were assessed in the absence and presence of the alpha(2)-adrenoceptor agonist UK14304 5-bromo-N-(4,5-dihydro-1H-imidazol-2-yl)-6-quinoxalinamine). In conditions of 50 microM GDP and 100 mM NaCl, UK14304 increased the apparent affinity of the specific [35S]GTPgammaS binding without changing the apparent density. Concentration-response curves to agonists of alpha(2)-adrenoceptors, mu-opioid, 5-HT(1A), cholinergic muscarinic, and GABA(B) receptors displayed, in the presence of NaCl, maximal stimulations between 24% and 61% with EC(50) values in the micromolar range. Selective antagonists shifted to the right the agonist-induced stimulation curves. The G(i)/G(o)-protein alkylating agent N-ethylmaleimide decreased basal [35S]GTPgammaS binding in a concentration-dependent manner and inhibited the stimulation induced by the different agonists. In cortical sections, [35S]GTPgammaS binding to gray matter was stimulated by the agonist UK14304. The present study demonstrates that functional studies of the receptor coupling to G(i)/G(o)-proteins can be performed in postmortem human brain samples.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adrenergic alpha-2 Receptor Agonists
  • Adrenergic alpha-Agonists / pharmacology
  • Autoradiography
  • Cerebral Cortex / metabolism*
  • Ethylmaleimide / pharmacology
  • GTP-Binding Proteins / agonists
  • GTP-Binding Proteins / metabolism*
  • Guanosine 5'-O-(3-Thiotriphosphate) / metabolism*
  • Guanosine Diphosphate / pharmacology
  • Humans
  • In Vitro Techniques
  • Membranes / metabolism
  • Sodium Chloride / pharmacology
  • Stimulation, Chemical
  • Sulfhydryl Reagents / pharmacology
  • Sulfur Radioisotopes
  • Time Factors


  • Adrenergic alpha-2 Receptor Agonists
  • Adrenergic alpha-Agonists
  • Sulfhydryl Reagents
  • Sulfur Radioisotopes
  • Guanosine Diphosphate
  • Guanosine 5'-O-(3-Thiotriphosphate)
  • Sodium Chloride
  • GTP-Binding Proteins
  • Ethylmaleimide