Paper Citing NAMD - Abstract
Arias, Hugo R.; Fedorov, Nikolai B.; Benson, Lisa C.; Lippiello, Patrick M.; Gatto, Greg J.; Feuerbach, Dominik; Ortells, Marcelo O.
Functional and Structural Interaction of (-)-Reboxetine with the Human alpha 4 beta 2 Nicotinic Acetylcholine Receptor
JOURNAL OF PHARMACOLOGY AND EXPERIMENTAL THERAPEUTICS, 344:113-123, JAN 2013
The interaction of the selective norepinephrine reuptake inhibitor (-)-reboxetine with the human alpha 4 beta 2 nicotinic acetylcholine receptor (nAChR) in different conformational states was studied by several functional and structural approaches. Patch-clamp and Ca2+-influx results indicate that (-)-reboxetine does not activate h alpha 4 beta 2 nAChRs via interaction with the orthosteric sites, but inhibits agonist-induced h alpha 4 beta 2 activation by a noncompetitive mechanism. Consistently, the results from the electrophysiology-based functional approach suggest that (-)-reboxetine may act via open channel block; therefore, it is capable of producing a use-dependent type of inhibition of the h alpha 4 beta 2 nAChR function. We tested whether (-)-reboxetine binds to the luminal [H-3] imipramine site. The results indicate that, although (-)-reboxetine binds with low affinity to this site, it discriminates between the resting and desensitized h alpha 4 beta 2 nAChR ion channels. Patch-clamp results also indicate that (-)-reboxetine progressively inhibits the h alpha 4 beta 2 nAChR with two-fold higher potency at the end of one-second application of agonist, compared with the peak current. The molecular docking studies show that (-)-reboxetine blocks the ion channel at the level of the imipramine locus, between M2 rings 6' and 14'. In addition, we found a (-)-reboxetine conformer that docks in the helix bundle of the alpha 4 subunit, near the middle region. According to molecular dynamics simulations, (-)-reboxetine binding is stable for both sites, albeit less stable than imipramine. The interaction of these drugs with the helix bundle might alter allostericaly the functionality of the channel. In conclusion, the clinical action of (-)-reboxetine may be produced (at least partially) by its inhibitory action on h alpha 4 beta 2 nAChRs.
