RESUMEN
Nicotine is an agonist of nicotinic acetylcholine receptors (nAChRs) that has been extensively used as a template for the synthesis of α4ß2-preferring nAChRs. Here, we used the N-methyl-pyrrolidine moiety of nicotine to design and synthesise novel α4ß2-preferring neonicotinic ligands. We increased the distance between the basic nitrogen and aromatic group of nicotine by introducing an ester functionality that also mimics acetylcholine (Fig. 2). Additionally, we introduced a benzyloxy group linked to the benzoyl moiety. Although the neonicotinic compounds fully inhibited binding of both [α-(125)I]bungarotoxin to human α7 nAChRs and [(3)H]cytisine to human α4ß2 nAChRs, they were markedly more potent at displacing radioligand binding to human α4ß2 nAChRs than to α7 nAChRs. Functional assays showed that the neonicotinic compounds behave as antagonists at α4ß2 and α4ß2α5 nAChRs. Substitutions on the aromatic ring of the compounds produced compounds that displayed marked selectivity for α4ß2 or α4ß2α5 nAChRs. Docking of the compounds on homology models of the agonist binding site at the α4/ß2 subunit interfaces of α4ß2 nAChRs suggested the compounds inhibit function of this nAChR type by binding the agonist binding site.