Radioiodinated D-(+)-N1-ethyl-2-iodolysergic acid diethylamide: A ligand for in vitro and in vivo studies of serotonin receptors

John R. Lever, Ursula A. Scheffel, John L. Musachio, Marigo Stathis, Henry N. Wagner

Research output: Contribution to journalArticlepeer-review

Abstract

Radioiodinated D-(+)-N1-ethyl-2-iodolysergic acid diethylamide ([125I]-EIL) has been evaluated as a ligand for in vitro and in vivo studies of cerebral serotonin 5-HT2 receptors. [125I]-EIL exhibited high affinity (KD = 209 pM for 5-HT2 receptors with a high degree of specific binding (80-95%) in membranes from rat prefrontal cortex. The regional distribution of [125I]-EIL binding in vivo to seven areas of mouse brain correlated significantly (Rs = 0.93) with known densities of 5-HT2 receptors. In vivo specificity, defined by tissue to cerebellum radioactivity ratios, reached a maximum for frontal cortex at 6 hr (21.2) and persisted through 16 hr (8.8). Ketanserin, a 5-HT2 receptors antagonist, fully inhibited binding in a dose dependent fashion in all brain regions except cerebellum. By contrast, blockers for dopamine D2, α- or β-adrenergic receptors did not significantly inhibit radioligand binding in any region. [125I]-EIL selectively labels 5-HT2 receptors in vivo with the highest specificity of any serotonergic ligand reported to date, indicating that [123I]-EIL should prove applicable to single photon emission computed tomography studies in living brain.

Original languageEnglish (US)
Pages (from-to)PL73-PL78
JournalLife Sciences
Volume48
Issue number15
DOIs
StatePublished - 1991

ASJC Scopus subject areas

  • Biochemistry, Genetics and Molecular Biology(all)
  • Pharmacology, Toxicology and Pharmaceutics(all)

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