91556-75-1

Direct comparison of pyridine versus pyrimidine substituents on a small but diverse set of ligands indicates that the pyrimidine substitution has the potential to enhance affinity and/or functional activity at α6 subunit-containing neuronal nicotinic rece

(Chemical Equation Presented) In an attempt to generate nicotinic acetylcholine receptor (nAChR) ligands selective for the α4β2 and α7 subtype receptors we designed and synthesized constrained versions of anabasine, a naturally occurring nAChR ligand. 2-(

The present report describes in vitro studies demonstrating that the heterocyclic substituted pyridine compound (±)-2-(3-pyridinyl)-1- azabicyclo[2.2.2]octane (RJR-2429) is extremely potent in activating human muscle nicotine ACh receptor (nAChR) (EC50 = 59 ± 17 nM; E(max) = 110 ± 09% vs. nicotine). RJR-2429 is markedly less potent in activating nAChRs in the clonal cell line PC12, with EC50 = 1100 ± 230 nM and E(max) = 85 ± 20% when compared with nicotine. The activation of a putative α3β4- containing nAChR in PC12 by RJR-2429 reveals a potency intermediate between nicotine and epibatidine (EC50 of 20,000 nM for nicotine and 30 nM for epibatidine). Dose-response curves for agonist-induced ileum contraction indicate that RJR-2429 is equipotent with nicotine, having an EC30 of approximately 2 μM. RJR-2429 binds with high affinity to α4β2 receptor subtype (K1 = 1.0 ± 0.3 nM), and chronic exposure results in significant up-regulation of the high-affinity [3H]nicotine binding sites. In addition, RJR-2429 does not activate nAChRs present in rat thalamic preparations but is a potent inhibitor of this receptor subtype. It antagonizes nicotine- stimulated ion flux in thalamic synaptosomes with an IC50 of 154 ± 37 nM. It also is a potent partial agonist at nAChRs mediating dopamine release from rat synaptosomal preparations (EC50 = 2 ± 1 nM; E(max) = 40%; epibatidine and nicotine have EC50 values of 0.4 and 100 nM, respectively). A model for the structure-activity profile of RJR-2429, nicotine and epibatidine was derived by molecular forcefield and quantum mechanics calculations and may provide important clues for the development of ligands selective for nAChR subtypes as probes in the life sciences or as potential therapeutic tools.

Compounds such as [5-chloronicotine, 5-fluoronornicotine, anabaseine, 5-fluoroanabaseine, 2-acetoxymethylquinuclidine or]2-(3-pyridyl)-quinuclidine are useful as locally acting and highly selective muscle relaxants. Each compound, when administered intravenously, acts to bind to musculoskeletal nicotinic receptor sites in a reversible manner causing transient depolarization, and hence provides for reversible muscle relaxation to a patient during anesthesia.