Persistent activation of α7 nicotinic ACh receptors associated with stable induction of different desensitized states

Roger L. Papke*, Clare Stokes, M. Imad Damaj, Ganesh A. Thakur, Khan Manther, Millet Treinin, Deniz Bagdas, Abhijit R. Kulkarni, Nicole A. Horenstein

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

27 Scopus citations

Abstract

Background and Purpose: GAT107 ((3aR,4S,9bS)-4-(4-bromo-phenyl)-3a,4,5,9b-tetrahydro-3H-cyclopenta-[c]quinoline-8-sulfonamide) is a positive allosteric modulator (PAM) and agonist of α7 nicotinic acetylcholine receptors (nAChRs)that can cause a prolonged period of primed potentiation of acetylcholine responses after drug washout. NS6740 is a silent agonist of α7 nAChRs that has little or no efficacy for activating the ion channel but induces stable desensitization states, some of which can be converted into channel-active states by PAMs. Although GAT107 and NS6740 appear to stably induce different non-conducting states, both agents are effective treatment for inflammation and inflammatory pain models. We sought to better understand how both of these drugs that have opposite effects on channel activation could regulate signal transduction. Experimental Approach: Voltage-clamp experiments were conducted with α7 nAChRs expressed in Xenopus oocytes. Key Results: Long-lived sensitivity to a PAM or to an agonist was produced by NS6740 or GAT107 respectively. With sequential applications, these two drugs induced varying levels of persistent activation, which is a unique condition for a receptor that is known for rapid desensitization. The non-conducting states induced by NS6740 or GAT107 differ in their sensitivity to an α7 nAChR-selective antagonist and in how effectively they promote current. Conclusions & Implications: Our data suggest that the persistent currents represent a dynamic interconversion between different stable desensitized states and the PAM-inducible conducting states. However, the similarity of NS6740 and GAT107 effects on inflammation and pain suggests that the different stable non-conducting states have common activity on signal transduction. Linked Articles: This article is part of a themed section on Nicotinic Acetylcholine Receptors. To view the other articles in this section visit http://onlinelibrary.wiley.com/doi/10.1111/bph.v175.11/issuetoc.

Original languageAmerican English
Pages (from-to)1838-1854
Number of pages17
JournalBritish Journal of Pharmacology
Volume175
Issue number11
DOIs
StatePublished - Jun 2018

Bibliographical note

Funding Information:
This work was supported by an NIH grant (GM57481) and an award from United States-Israel Binational Science Foundation 2013055. tkP3BzPB was generously provided by Dr Peter Crooks.

Publisher Copyright:
© 2017 The British Pharmacological Society

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