title: Interaction of bispyridinium compounds with the orthosteric binding site of human α7 and Torpedo californica nicotinic acetylcholine receptors (nAChRs).
abstract: Standard treatment of poisoning by organophosphorus (OP) nerve agents with atropine and oximes lacks efficacy with different nerve agents. A direct pharmacologic intervention at the nicotinic acetylcholine receptor (nAChR) was proposed as an alternative therapeutic approach and promising in vitro and in vivo results were obtained with the bispyridinium compound SAD-128. In addition, a number of SAD-128 analogues improved neuromuscular transmission of soman-poisoned diaphragms in vitro. We investigated the interaction of six of these SAD-128 analogues with the orthosteric binding site of the human α7 nAChR and Torpedo californica nAChR with a high-throughput assay using radioactive ligands. The determined affinity constants indicate a weak interaction of three test compounds (K(i) in the micromolar range) with both receptors, but no interaction could be recorded with the other three test compounds. The six SAD-128 analogues showed a low intrinsic inhibitory potency with human acetylcholinesterase (IC₅₀ > 400 μM). In conclusion, the results of the present study do not indicate a correlation between the affinity to the orthosteric binding site and the functional improvement of neuromuscular transmission and it is assumed that other mechanisms contribute to the therapeutic effect of the tested compounds.
authors.affiliation: Bundeswehr Institute of Pharmacology and Toxicology, Neuherbergstrasse 11, 80937 Munich, Germany. KarinNiessen@bundeswehr.org
authors.forename: K V
authors.initials: KV
authors.lastname: Niessen
authors.forename: J E H
authors.initials: JE
authors.lastname: Tattersall
authors.forename: C M
authors.initials: CM
authors.lastname: Timperley
authors.forename: M
authors.initials: M
authors.lastname: Bird
authors.forename: C
authors.initials: C
authors.lastname: Green
authors.forename: T
authors.initials: T
authors.lastname: Seeger
authors.forename: H
authors.initials: H
authors.lastname: Thiermann
authors.forename: F
authors.initials: F
authors.lastname: Worek
mesh_terms: D000110:Acetylcholinesterase / Q000378:metabolism; D000818:Animals; D001665:Binding Sites; D018929:Cell Culture Techniques; D045744:Cell Line, Tumor; D002462:Cell Membrane / Q000378:metabolism; D004557:Electric Organ / Q000378:metabolism; D004910:Erythrocyte Membrane / Q000201:enzymology; D057166:High-Throughput Screening Assays; D006801:Humans; D008024:Ligands; D015394:Molecular Structure; D011485:Protein Binding; D011726:Pyridinium Compounds / Q000737:chemistry / Q000494:pharmacology*; D011869:Radioligand Assay; D051381:Rats; D011978:Receptors, Nicotinic / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D014101:Torpedo / Q000378:metabolism*; D014162:Transfection; D064569:alpha7 Nicotinic Acetylcholine Receptor
chemical_list: C579167:Chrna7 protein, human; C579165:Chrna7 protein, rat; D008024:Ligands; D011726:Pyridinium Compounds; D011978:Receptors, Nicotinic; D064569:alpha7 Nicotinic Acetylcholine Receptor; D000110:Acetylcholinesterase