Subclasses of histamine H3 antagonist binding sites in rat brain

Paul Cumming, Albert Gjedde

Research output: Contribution to journalArticlepeer-review

Abstract

Histamine H3 antagonists have been reported to discriminate subclasses of histamine H3 agonist binding in rat cortical membranes. This phenomenon was investigated by autoradiography of cryostat sections of rat forebrain labelled with [3H]Nα- methylhistamine ([3H]NAHM, 4 nM). Displacement curves with thioperamide detected a single site in cortex and striatum (pIC50 8.18±0.03). However, Hill coefficients (nH 0.51±0.12) suggested the possible presence of multiple binding sites. Displacement with burimamide was consistent with two site models in all brain regions examined (pIC50(A) 7.9±1.5; pIC50(B) 5.6±0.7), except for the medial septum where a single site was detected. Elsewhere, the relative abundance of the two sites displaced by burimamide (H3A: H3B) appeared to be 1:2. Thioperamide may have failed to discriminate two sites because the IC50s were too similar to be distinguished in the present autoradiographic study.

Original languageEnglish (US)
Pages (from-to)203-207
Number of pages5
JournalBrain research
Volume641
Issue number2
DOIs
StatePublished - Apr 4 1994

Keywords

  • Basal ganglion
  • Brain
  • H receptor
  • Histamine
  • Subtype

ASJC Scopus subject areas

  • Neuroscience(all)
  • Molecular Biology
  • Clinical Neurology
  • Developmental Biology

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