Structural Determinants of Oxantel Analogs Reveal Modulatory Selectivity of α3β2 and α4β2 Neuronal Nicotinic Acetylcholine Receptors.

Nicotinic acetylcholine receptors (nAChRs), ligand-gated ion channels involved in key physiological processes, show pharmacological diversity across receptor subtypes and species. The structurally similar anthelmintic compounds pyrantel, morantel, and oxantel differentially affect the α3β2 and α4β2 nAChR subtypes. Mutation analysis located the modulator binding sites to β(+)/α(-) interface pockets, homologous to the orthosteric agonist sites.

Structural Determinants for the Mode of Action of Imidazopyridine DS2 at δ-Containing γ-Aminobutyric Acid Type A Receptors.

Despite the therapeutic relevance of δ-containing γ-aminobutyric acid type A receptors (GABARs) and the need for δ-selective compounds, the structural determinants for the mode and molecular site of action of δ-selective positive allosteric modulator imidazo[1,2-a]pyridine DS2 remain elusive. To guide the quest for insight, we synthesized a series of DS2 analogues guided by a structural receptor model. Using a fluorescence-based fluorometric imaging plate reader membrane potential assay, we found that the δ-selectivity and the pharmacological profile are severely affected by substituents in the 5-position of the imidazopyridine core scaffold.