Sazetidine-A, A Novel Ligand That Desensitizes α4β2 Nicotinic Acetylcholine Receptors without Activating Them
Abstract
Neuronal nicotinic acetylcholine receptors (nAChRs) are ligand-gated ion channels found throughout the central and peripheral nervous systems. They are crucial to normal physiology and have been clearly implicated in nicotine addiction. In addition, they are possible therapeutic targets in a wide range of pathological conditions, including cognitive disorders, Parkinson's disease, and neuropathic pain. Nicotinic ligands are usually classified as agonists (or partial agonists), competitive antagonists, or noncompetitive antagonists. Sazetidine-A is a new nicotinic ligand that shows a different pharmacological profile from any of these known classes of ligands. Sazetidine-A competes with very high binding affinity (Ki approximately 0.5 nM) and selectivity for the alpha4beta2 nAChR subtype (Ki ratio alpha3beta4/alpha4beta2 approximately 24,000). Despite its high affinity, sazetidine-A neither activates nAChR channel function nor prevents channel activation when it is applied simultaneously with nicotine. However, when it is pre-incubated for 10 min with the receptors, it potently blocks nicotine-stimulated alpha4beta2 nAChR function (IC50 approximately 30 nM). The action of sazetidine-A may be explained by its very low affinity for the resting conformation of the alpha4beta2 nAChRs, and its very high affinity for the desensitized state of the receptor. We propose that sazetidine-A is a "silent desensitizer" of nAChRs, meaning that it desensitizes the receptor without first activating it. Furthermore, comparison of the effects of sazetidine-A and nicotine at alpha4beta2 nAChRs suggests that the predominant effects of nicotine and other nicotinic agonists are related to desensitization of the receptors and that sazetidine-A potently mimics these effects.
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Sazetidine-A has high affinity and selectivity for α4β2 nAChRs, but not α3β4 or α7 nAChRs.
“Sazetidine-A is a recently developed nicotinic compound with high affinity and selectivity for a4b2 nAChRs, but not a3b4 or a7 nAChRs (Xiao et al, 2006), that quickly and thoroughly desensitizes the receptor after brief partial agonism (Xiao et al, 2006; Zwart et al, 2008).”
From Divergent Functional Effects of Sazetidine-A and Varenicline During Nicotine Withdrawal (2013) · cites this paper as Xiao et al, 2006
Sazetidine-A quickly and thoroughly desensitizes the receptor after brief partial agonism.
“Sazetidine-A is a recently developed nicotinic compound with high affinity and selectivity for a4b2 nAChRs, but not a3b4 or a7 nAChRs (Xiao et al, 2006), that quickly and thoroughly desensitizes the receptor after brief partial agonism (Xiao et al, 2006; Zwart et al, 2008).”
From Divergent Functional Effects of Sazetidine-A and Varenicline During Nicotine Withdrawal (2013) · cites this paper as Xiao et al, 2006
Low concentrations of sazetidine-A profoundly desensitize α4β2 nAChRs for prolonged periods.
“In vitro studies show that low concentrations of sazetidine-A profoundly desensitize a4b2 nAChRs for prolonged periods (Xiao et al, 2006; Zwart et al, 2008).”
From Divergent Functional Effects of Sazetidine-A and Varenicline During Nicotine Withdrawal (2013) · cites this paper as Xiao et al, 2006
These results may be due to differential effects of varenicline and sazetidine-A on nAChR activation and desensitization.
“Therefore, these results may be due to differential effects of varenicline and sazetidine-A on nAChR activation and desensitization (Caldarone et al, 2011; Rollema et al, 2010; Xiao et al, 2006; Zwart et al, 2008).”
From Divergent Functional Effects of Sazetidine-A and Varenicline During Nicotine Withdrawal (2013) · cites this paper as Xiao et al, 2006
Sazetidine-A strongly and selectively desensitizes α4β2 nicotinic receptors.
“A newly developed nicotinic partial agonist, sazetidine-A, potently and selectively desensitizes ␣42 nicotinic acetylcholine receptors (Xiao et al., 2006), but it has very low affinities for all other nAChR subtypes (Xiao et al., 2006;Zwart et al., 2008).”
From Nicotinic Partial Agonists Varenicline and Sazetidine-A Have Differential Effects on Affective Behavior (2010) · cites this paper as Xiao et al., 2006
Sazetidine-A binds with very low affinity to all other nicotinic receptor subtypes.
“A newly developed nicotinic partial agonist, sazetidine-A, potently and selectively desensitizes ␣42 nicotinic acetylcholine receptors (Xiao et al., 2006), but it has very low affinities for all other nAChR subtypes (Xiao et al., 2006;Zwart et al., 2008).”
From Nicotinic Partial Agonists Varenicline and Sazetidine-A Have Differential Effects on Affective Behavior (2010) · cites this paper as Xiao et al., 2006
The Ki values of sazetidine-A and varenicline at α4β2 nAChRs are very similar, 0.4 and 0.2 nM respectively.
“Although the K i values for sazetidine-A and varenicline at ␣42 nAChRs are very similar (0.4 and 0.2 nM, respectively) (Xiao et al., 2006;Rollema et al., 2007)”
From Nicotinic Partial Agonists Varenicline and Sazetidine-A Have Differential Effects on Affective Behavior (2010) · cites this paper as Xiao et al., 2006
Sazetidine-A is a high-affinity, highly selective partial agonist at α4β2 nicotinic acetylcholine receptors.
“Sazetidine-A is a high-affinity, highly selective partial agonist of ␣42 nAChRs (Xiao et al., 2006;Cucchiaro et al., 2008).”
From Nicotinic Partial Agonists Varenicline and Sazetidine-A Have Differential Effects on Affective Behavior (2010) · cites this paper as Xiao et al., 2006
Saz-A has an affinity for α4β2 nAChRs approximately 25 times higher than nicotine's.
“Saz-A has an affinity for ␣42 nAChRs approximately 25 times higher than nicotine's (Xiao et al., 2006)”
From Chronic Sazetidine-A at Behaviorally Active Doses Does Not Increase Nicotinic Cholinergic Receptors in Rodent Brain (2012) · cites this paper as Xiao et al., 2006
Saz-A potently and selectively desensitizes α4β2 nAChRs.
“Saz-A also potently and selectively desensitizes these receptors (Xiao et al., 2006).”
From Chronic Sazetidine-A at Behaviorally Active Doses Does Not Increase Nicotinic Cholinergic Receptors in Rodent Brain (2012) · cites this paper as Xiao et al., 2006
Other nicotinic partial agonists such as sazetidine-A and ispronicline also have antidepressant effects.
“other nicotinic partial agonists such as sazetidine-A and ispronicline (TC-1734 or AZD3480) also have antidepressant effects (Gatto et al., 2004; Xiao et al., 2006).”
From Nicotine addiction and psychiatric disorders (2015) · cites this paper as Xiao et al., 2006
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References 52 · Cited by 141
- Authors
- Xiao, Y., Fan, H., Musachio, J. L., Wei, Z.-L., Chellappan, S. K., Kozikowski, A. P., & Kellar, K. J.
- Affiliations
- Georgetown University (US)
- Johns Hopkins University (US)
- National Institutes of Health (US)
- University of Illinois Chicago (US)
- Venue
- Molecular Pharmacology
- Publisher
- Elsevier BV
- Published
- 2006-10
- Volume
- 70
- Issue
- 4
- Pages
- 1454-1460
- ISSN
- 0026-895X (ISSN-L)
- OpenAlex
- W2133701994
- Cited by
- 141
- References
- 52
- Citations by year
- 2026: 3 · 2025: 1 · 2024: 3 · 2023: 5 · 2022: 4 · 2021: 4 · 2020: 2 · 2019: 8 · 2018: 6 · 2017: 5 · 2016: 9 · 2015: 14 · 2014: 16 · 2013: 10 · 2012: 12
- FWCI
- 2.18
- Type
- journal article
- Language
- en
- Open access
- closed
- Locations
- Molecular Pharmacology (publishedVersion)
- PubMed (publishedVersion)
- Funders
- National Institute on Drug Abuse (DA017980, R01DA017980, DA13199, DA 12976, R21DA013199)
- Topics
- Life Sciences › Biochemistry, Genetics and Molecular Biology › Molecular Biology › Nicotinic Acetylcholine Receptors Study
- Life Sciences › Biochemistry, Genetics and Molecular Biology › Molecular Biology › Receptor Mechanisms and Signaling
- Life Sciences › Neuroscience › Cellular and Molecular Neuroscience › Neuroscience and Neuropharmacology Research
- Keywords
- α4β2 nicotinic acetylcholine receptor, receptor desensitization, nicotine, ligand-gated ion channels, receptor selectivity, receptor conformational states
- MeSH terms
- Azetidines, Binding Sites, Cell Line, Dose-Response Relationship, Drug, Humans, Pyridines, Radioligand Assay, Receptors, Nicotinic, Molecular Structure, Up-Regulation, Nicotinic Agonists
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