Guanosine 5'-(gamma-[35S]thio)triphosphate autoradiography allows selective detection of histamine H3 receptor-dependent G protein activation in rat brain tissue sections

J Neurochem. 1998 Aug;71(2):808-16. doi: 10.1046/j.1471-4159.1998.71020808.x.


Histamine elicits its biological effects via three distinct G protein-coupled receptors, termed H1, H2, and H3. We have used guanosine 5'-(gamma-[35S]thio)triphosphate (GTPgamma[35S]) autoradiography to localize histamine receptor-dependent G protein activation in rat brain tissue sections. Initial studies revealed that in basal conditions, adenosine was present in tissue sections in sufficient concentrations to generate an adenosine A1 receptor-dependent GTPgamma[35S] signal in several brain regions. All further incubations therefore contained 8-cyclopentyl-1,3-dipropylxanthine (10 microM), a selective A1 receptor antagonist. Histamine elicited dose-dependent increments in GTPgamma[35S] binding to discrete anatomical structures, most notably the caudate putamen, cerebral cortex, and substantia nigra. The overall anatomical pattern of the histamine-evoked binding response closely reflects the known distribution of H3 binding sites and was faithfully mimicked by N(alpha)-methylhistamine, (R)-alpha-methylhistamine, and immepip, three H3-selective agonists. In all regions examined, the GTPgamma[35S] signal was reversed with thioperamide and clobenpropit, two potent H3-selective antagonists, whereas mepyramine, a specific H1 antagonist, and cimetidine, a prototypic H2 antagonist, proved ineffective. These data indicate that in rat brain tissue sections, GTPgamma[35S] autoradiography selectively detects H3 receptor-dependent signaling in response to histamine stimulation. As the existing evidence suggests that GTPgamma[35S] autoradiography preferentially reveals responses to G(i/o)-coupled receptors, our data indicate that most, if not all, central H3 binding sites represent functional receptors coupling to G(i/o), the inhibitory class of G proteins. Besides allowing more detailed studies on H3 receptor signaling within anatomically restricted regions of the CNS, GTPgamma[35S] autoradiography offers a novel approach for functional in vitro screening of H3 ligands.

MeSH terms

  • Adenosine / pharmacology
  • Animals
  • Autoradiography
  • Basal Ganglia / chemistry
  • Basal Ganglia / metabolism
  • Brain Chemistry / physiology*
  • Cerebral Cortex / chemistry
  • Cerebral Cortex / metabolism
  • GTP-Binding Proteins / metabolism*
  • Guanosine 5'-O-(3-Thiotriphosphate) / pharmacology*
  • Guanosine Diphosphate / pharmacology
  • Histamine / pharmacology
  • Histamine Antagonists / pharmacology
  • Histamine H1 Antagonists / pharmacology
  • Male
  • Piperidines / pharmacology
  • Protein Binding / drug effects
  • Pyrilamine / pharmacology
  • Rats
  • Rats, Wistar
  • Receptors, Histamine H3 / metabolism*
  • Signal Transduction / drug effects
  • Signal Transduction / physiology
  • Substantia Nigra / chemistry
  • Substantia Nigra / metabolism
  • Sulfur Radioisotopes
  • Xanthines / pharmacology


  • Histamine Antagonists
  • Histamine H1 Antagonists
  • Piperidines
  • Receptors, Histamine H3
  • Sulfur Radioisotopes
  • Xanthines
  • Guanosine Diphosphate
  • Guanosine 5'-O-(3-Thiotriphosphate)
  • Histamine
  • 1,3-dipropyl-8-cyclopentylxanthine
  • GTP-Binding Proteins
  • Pyrilamine
  • thioperamide
  • Adenosine