Scientific article

[3H]A-585539 [(1S,4S)-2,2-dimethyl-5-(6-phenylpyridazin-3-yl)-5-aza-2-azoniabicyclo[2.2 .1]heptane], a novel high-affinity alpha7 neuronal nicotinic receptor agonist: radioligand binding characterization to rat and human brain

Published inThe Journal of pharmacology and experimental therapeutics, vol. 324, no. 1, p. 179-187
Publication date2008

Receptor binding was characterized for [(3)H](1S,4S)-2,2-dimethyl-5-(6-phenylpyridazin-3-yl)-5-aza-2-azoniabicycl o[2.2.1]heptane ([(3)H]A-585539), a selective high-affinity alpha7 nicotinic acetylcholine receptor (nAChR) agonist with rapid kinetics, low nonspecific binding, and high specific activity. At 4 degrees C, the association was monophasic and rapid (t((1/2)) = 8.0 min); dissociation was slower (t((1/2)) = 64.2 min). The K(d) in rat brain at 4 degrees C was 0.063 nM, whereas at 22 and 37 degrees C, the K(d) values were 0.188 and 0.95 nM, respectively. In contrast, the B(max) (34 fmol/mg protein) was unaffected by temperature. In human cortex, [(3)H]A-585539 bound with a K(d) of 0.066 nM and a B(max) of 5.8 fmol/mg protein at 4 degrees C, whereas under similar conditions, specific [(3)H]methyllycaconitine ([(3)H]MLA) binding was not measurable. A number of agonist and antagonist nAChR ligands displaced binding to rat brain membranes with rank order of affinity similar to that for [(3)H]MLA, and in general, a 5 to 10-fold higher affinity was observed for [(3)H]A-585539 binding. There was also a good correlation of K(i) values between [(3)H]A-585539 binding to rat brain and human cortex. The use of a alpha7/5-hydroxytryptamine type-3 chimera revealed that the N-terminal domain of alpha7 nAChR was sufficient to faithfully reproduce the pharmacology of [(3)H]A-585539 binding. Autoradiographic studies comparing [(3)H]A-585539 and [(125)I]alpha-bungarotoxin revealed a similar pattern of labeling in the rat. In summary, [(3)H]A-585539 was shown to have excellent binding characteristics in rat and human brain and represents the first high-affinity alpha7 agonist radioligand with utility in the characterization of this important nAChR subtype that is targeted toward ameliorating cognitive deficits underlying neuropsychiatric and neurodegenerative disorders.

  • Aconitine/analogs & derivatives/metabolism
  • Animals
  • Benzamides/metabolism
  • Bicyclo Compounds/metabolism
  • Bicyclo Compounds, Heterocyclic/*metabolism
  • Brain/*metabolism
  • Bridged Compounds/metabolism
  • Bungarotoxins/metabolism
  • Cell Line
  • Humans
  • Nicotine/metabolism
  • Nicotinic Agonists/*metabolism
  • Nicotinic Antagonists/metabolism
  • Pyridazines/*metabolism
  • Radioligand Assay
  • Rats
  • Rats, Sprague-Dawley
  • Receptors, Nicotinic/*metabolism
  • Spiro Compounds/metabolism
Citation (ISO format)
ANDERSON, David J. et al. [3H]A-585539 [(1S,4S)-2,2-dimethyl-5-(6-phenylpyridazin-3-yl)-5-aza-2-azoniabicyclo[2.2 .1]heptane], a novel high-affinity alpha7 neuronal nicotinic receptor agonist: radioligand binding characterization to rat and human brain. In: The Journal of pharmacology and experimental therapeutics, 2008, vol. 324, n° 1, p. 179–187. doi: 10.1124/jpet.107.130062
Updates (1)
ISSN of the journal0022-3565

Technical informations

Creation03/27/2012 9:23:43 AM
First validation03/27/2012 9:23:43 AM
Update time03/14/2023 5:20:55 PM
Status update03/14/2023 5:20:54 PM
Last indexation10/18/2023 1:33:56 PM
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