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Yenugonda VM, Xiao Y, Levin ED, Rezvani AH, Tran T, Al-Muhtasib N, Sahibzada N, Xie T, Wells C, Slade S, Johnson JE, Dakshanamurthy S, Kong HS, Tomita Y, Liu Y, Paige M, Kellar KJ, Brown ML. Design, synthesis and discovery of picomolar selective α4β2 nicotinic acetylcholine receptor ligands. J Med Chem 2013; 56:8404-21. [PMID: 24047231 DOI: 10.1021/jm4008455] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
Developing novel and selective compounds that desensitize α4β2 nicotinic acetylcholine receptors (nAChRs) could provide new effective treatments for nicotine addiction, as well as other disorders. Here we report a new class of nAChR ligands that display high selectivity and picomolar binding affinity for α4β2 nicotinic receptors. The novel compounds have Ki values in the range of 0.031-0.26 nM and properties that should make them good candidates as drugs acting in the CNS. The selected lead compound 1 (VMY-2-95) binds with high affinity and potently desensitizes α4β2 nAChRs. At a dose of 3 mg/kg, compound 1 significantly reduced rat nicotine self-administration. The overall results support further characterizations of compound 1 and its analogues in preclinical models of nicotine addiction and perhaps other disorders involving nAChRs.
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Affiliation(s)
- Venkata M Yenugonda
- Center for Drug Discovery, Georgetown University Medical Center , 3970 Reservoir Road NW, Research Building, EP-07, Washington, D.C. 20057, United States
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Divergent functional effects of sazetidine-a and varenicline during nicotine withdrawal. Neuropsychopharmacology 2013; 38:2035-47. [PMID: 23624742 PMCID: PMC3746688 DOI: 10.1038/npp.2013.105] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/17/2012] [Revised: 04/03/2013] [Accepted: 04/20/2013] [Indexed: 01/15/2023]
Abstract
Smoking is the largest preventable cause of death in the United States. Furthermore, a recent study found that <10% of quit attempts resulted in continuous abstinence for 1 year. With the introduction of pharmacotherapies like Chantix (varenicline), a selective α4β2 nicotinic partial agonist, successful quit attempts have significantly increased. Therefore, novel subtype-specific nicotinic drugs, such as sazetidine-A, present a rich area for investigation of therapeutic potential in smoking cessation. The present studies examine the anxiety-related behavioral and functional effects of the nicotinic partial agonists varenicline and sazetidine-A during withdrawal from chronic nicotine in mice. Our studies indicate that ventral hippocampal-specific infusions of sazetidine-A, but not varenicline, are efficacious in reducing nicotine withdrawal-related anxiety-like phenotypes in the novelty-induced hypophagia (NIH) paradigm. To further investigate functional differences between these partial agonists, we utilized voltage-sensitive dye imaging (VSDi) in ventral hippocampal slices to determine the effects of sazetidine-A and varenicline in animals chronically treated with saline, nicotine, or undergoing 24 h withdrawal. These studies demonstrate a functional dissociation of varenicline and sazetidine-A on hippocampal network activity, which is directly related to previous drug exposure. Furthermore, the effects of the nicotinic partial agonists in VSDi assays are significantly correlated with their behavioral effects in the NIH test. These findings highlight the importance of drug history in understanding the mechanisms through which nicotinic compounds may be aiding smoking cessation in individuals experiencing withdrawal-associated anxiety.
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Loughead J, Ray R, Wileyto EP, Ruparel K, O'Donnell GP, Senecal N, Siegel S, Gur RC, Lerman C. Brain activity and emotional processing in smokers treated with varenicline. Addict Biol 2013; 18:732-8. [PMID: 21507156 DOI: 10.1111/j.1369-1600.2011.00324.x] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Prior evidence suggests that varenicline, an effective smoking cessation treatment, may relieve negative affective signs of nicotine withdrawal. We examined varenicline effects on emotional processing in 25 abstinent smokers after 13 days of varenicline and placebo using a within-subject cross-over design. Blood oxygen level dependent (BOLD) functional magnetic resonance imaging was acquired while subjects completed a face emotion identification task. Results showed a significant drug effect, characterized by decreased BOLD signal in dorsal anterior cingulate/medial frontal cortex, occipital cortex and thalamus. Increased BOLD signal was observed in the middle temporal gyrus. Varenicline improved correct response time; however, neither BOLD signal nor performance effects were moderated by emotion type. An exploratory region of interest analysis suggests that varenicline reduced amygdala activity independent of emotional valence. Taken together, these results suggest that observed drug effects on brain activity do not reflect affective changes but rather enhanced early processing of perceptual features of facial stimuli.
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Affiliation(s)
- James Loughead
- Brain Behavior Laboratory, Department of Psychiatry, University of Pennsylvania, Philadelphia, PA 19104, USA
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Sajja RK, Rahman S. Cytisine modulates chronic voluntary ethanol consumption and ethanol-induced striatal up-regulation of ΔFosB in mice. Alcohol 2013; 47:299-307. [PMID: 23601929 DOI: 10.1016/j.alcohol.2013.02.003] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2012] [Revised: 02/19/2013] [Accepted: 02/19/2013] [Indexed: 01/23/2023]
Abstract
Chronic administration of ethanol induces persistent accumulation of ΔFosB, an important transcription factor, in the midbrain dopamine system. This process underlies the progression to addiction. Previously, we have shown that cytisine, a neuronal nicotinic acetylcholine receptor (nAChR) partial agonist, reduces various ethanol-drinking behaviors and ethanol-induced striatal dopamine function. However, the effects of cytisine on chronic ethanol drinking and ethanol-induced up-regulation of striatal ΔFosB are not known. Therefore, we examined the effects of cytisine on chronic voluntary ethanol consumption and associated striatal ΔFosB up-regulation in C57BL/6J mice using behavioral and biochemical methods. Following the chronic voluntary consumption of 15% (v/v) ethanol under a 24-h two-bottle choice intermittent access (IA; 3 sessions/week) or continuous access (CA; 24 h/d and 7 d/week) paradigm, mice received repeated intraperitoneal injections of saline or cytisine (0.5 or 3.0 mg/kg). Ethanol and water intake were monitored for 24 h post-treatment. Pretreatment with cytisine (0.5 or 1.5 mg/kg) significantly reduced ethanol consumption and preference in both paradigms at 2 h and 24 h post-treatment. The ΔFosB levels in the ventral and dorsal striatum were determined by Western blotting 18-24 h after the last point of ethanol access. In addition, cytisine (0.5 mg/kg) significantly attenuated up-regulation of ΔFosB in the ventral and dorsal striatum following chronic ethanol consumption in IA and CA paradigms. The results indicate that cytisine modulates chronic voluntary ethanol consumption and reduces ethanol-induced up-regulation of striatal ΔFosB. Further, the data suggest a critical role of nAChRs in chronic ethanol-induced neurochemical adaptations associated with ethanol addiction.
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Affiliation(s)
- Ravi Kiran Sajja
- Department of Pharmaceutical Sciences, College of Pharmacy, South Dakota State University, Box 2202C, Avera Health and Science Center (SAV 265), Brookings, SD 57007, USA
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Sajja RK, Rahman S. Cytisine modulates chronic voluntary ethanol consumption and ethanol-induced striatal up-regulation of ΔFosB in mice. Alcohol 2013. [DOI: https://doi.org/10.1016/j.alcohol.2013.02.003] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
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Allosteric modulators of α4β2 nicotinic acetylcholine receptors: a new direction for antidepressant drug discovery. Future Med Chem 2013. [PMID: 23190109 DOI: 10.4155/fmc.12.172] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023] Open
Abstract
Allosteric modulation of ligand-gated ion channels has been intensively studied in the past three decades and is now an established strategy to control receptor function in numerous disease states. Allosteric sites on the GABA(A) receptor are targets for widely prescribed drugs that are used for a variety of pathophysiological states including insomnia and epilepsy. Modulators might be especially valuable to control receptors for which the design of selective orthosteric drugs has proven difficult due to safety issues (e.g., α4β2 nicotinic acetylcholine receptors and might have several advantages over orthosteric ligands. Modulators influence the action of the endogenous agonist but generally have no effect of their own on the unoccupied receptor. Moreover, the higher subtype selectivity exerted by modulators and that the effects of modulators depend on the simultaneous presence of agonist help to overcome safety problems by preventing over-dosage compared with the administration of orthosteric drugs.
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Liu Y, Richardson J, Tran T, Al-Muhtasib N, Xie T, Yenugonda VM, Sexton HG, Rezvani AH, Levin ED, Sahibzada N, Kellar KJ, Brown ML, Xiao Y, Paige M. Chemistry and pharmacological studies of 3-alkoxy-2,5-disubstituted-pyridinyl compounds as novel selective α4β2 nicotinic acetylcholine receptor ligands that reduce alcohol intake in rats. J Med Chem 2013; 56:3000-11. [PMID: 23540678 PMCID: PMC3809750 DOI: 10.1021/jm4000374] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Neuronal acetylcholine receptors mediate the addictive effects of nicotine and may also be involved in alcohol addiction. Varenicline, an approved smoking cessation medication, showed clear efficacy in reducing alcohol consumption in heavy-drinking smokers. More recently, sazetidine-A, which selectively desensitizes α4β2 nicotinic receptors, was shown to significantly reduce alcohol intake in a rat model. To develop novel therapeutics for treating alcohol use disorder, we designed and synthesized novel sazetidine-A analogues containing a methyl group at the 2-position of the pyridine ring. In vitro pharmacological studies revealed that some of the novel compounds showed overall pharmacological property profiles similar to that of sazetidine-A but exhibited reduced agonist activity across all nicotinic receptor subtypes tested. In rat studies, compound (S)-9 significantly reduced alcohol uptake. More importantly, preliminary results from studies in a ferret model indicate that these novel nAChR ligands have an improved adverse side-effect profile in comparison with that of varenicline.
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Affiliation(s)
- Yong Liu
- Center of Drug Discovery, Georgetown University Medical Center, 3970 Reservoir Road, NW, Washington, D.C. 20057
| | - Janell Richardson
- Department of Pharmacology and Physiology, Georgetown University School of Medicine, 3900 Reservoir Road, NW, Washington, D.C. 20057
| | - Thao Tran
- Department of Pharmacology and Physiology, Georgetown University School of Medicine, 3900 Reservoir Road, NW, Washington, D.C. 20057
| | - Nour Al-Muhtasib
- Department of Pharmacology and Physiology, Georgetown University School of Medicine, 3900 Reservoir Road, NW, Washington, D.C. 20057
| | - Teresa Xie
- Department of Pharmacology and Physiology, Georgetown University School of Medicine, 3900 Reservoir Road, NW, Washington, D.C. 20057
| | - Venkata Mahidhar Yenugonda
- Center of Drug Discovery, Georgetown University Medical Center, 3970 Reservoir Road, NW, Washington, D.C. 20057
| | - Hannah G. Sexton
- Department of Psychiatry and Behavioral Sciences, Duke University Medical Center, Durham, NC 27710
| | - Amir H. Rezvani
- Department of Psychiatry and Behavioral Sciences, Duke University Medical Center, Durham, NC 27710
| | - Edward D. Levin
- Department of Psychiatry and Behavioral Sciences, Duke University Medical Center, Durham, NC 27710
| | - Niaz Sahibzada
- Department of Pharmacology and Physiology, Georgetown University School of Medicine, 3900 Reservoir Road, NW, Washington, D.C. 20057
| | - Kenneth J. Kellar
- Department of Pharmacology and Physiology, Georgetown University School of Medicine, 3900 Reservoir Road, NW, Washington, D.C. 20057
| | - Milton L. Brown
- Center of Drug Discovery, Georgetown University Medical Center, 3970 Reservoir Road, NW, Washington, D.C. 20057
| | - Yingxian Xiao
- Department of Pharmacology and Physiology, Georgetown University School of Medicine, 3900 Reservoir Road, NW, Washington, D.C. 20057
| | - Mikell Paige
- Center of Drug Discovery, Georgetown University Medical Center, 3970 Reservoir Road, NW, Washington, D.C. 20057
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58
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Nicotinic acetylcholine receptors: From basic science to therapeutics. Pharmacol Ther 2013; 137:22-54. [DOI: 10.1016/j.pharmthera.2012.08.012] [Citation(s) in RCA: 382] [Impact Index Per Article: 34.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/20/2012] [Accepted: 08/20/2012] [Indexed: 12/14/2022]
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Anderson SM, Brunzell DH. Low dose nicotine and antagonism of β2 subunit containing nicotinic acetylcholine receptors have similar effects on affective behavior in mice. PLoS One 2012; 7:e48665. [PMID: 23144922 PMCID: PMC3492489 DOI: 10.1371/journal.pone.0048665] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/2012] [Accepted: 09/28/2012] [Indexed: 12/19/2022] Open
Abstract
Nicotine leads to both activation and desensitization (inactivation) of nicotinic acetylcholine receptors (nAChRs). This study tested the hypothesis that nicotine and a selective antagonist of β2*nAChRs would have similar effects on affective behavior. Adult C57BL/6J male mice were tested in a conditioned emotional response (CER) assay which evaluates the ability of an aversive stimulus to inhibit goal-directed behavior. Mice lever-pressed for a saccharin reinforcer according to a variable schedule of reinforcement during sessions in which two presentations of a compound light/tone conditioned stimulus (CS) co-terminated with a 0.1 or 0.3 mA, 0.5 s footshock unconditioned stimulus (US). During testing in the absence of the US, mice received doses of i.p. nicotine (0, 0.0032, 0.01, 0.032, 0.1 mg/kg) or a selective β2 subunit containing nAChR (β2*nAChR) antagonist dihydro-beta-erythroidine (0, 0.1, 0.3, 1.0, 3.0 mg/kg DHβE). There was a dose-dependent effect of nicotine revealing that only low doses (0.01, 0.032 mg/kg) increased CER suppression ratios (SR) in these mice. DHβE also dose-dependently increased SR at the 3 mg/kg dose. In ethological measures of fear-/anxiety-like behavior, these doses of nicotine and DHβE significantly reduced digging behavior in a marble burying task and 0.3 mg/kg DHβE promoted open-arm activity in the elevated plus maze. Doses of nicotine and DHβE that altered affective behavior had no effect on locomotor activity. Similar to previous reports with anxiolytic drugs, low dose nicotine and DHβE reversed SR in a CER assay, decreased digging in a marble burying assay and increased open arm activity in the elevated plus maze. This study provides evidence that inactivation of β2*nAChRs reduces fear-like and anxiety-like behavior in rodents and suggests that smokers may be motivated to smoke in part to desensitize their β2*nAChRs. These data further identify β2*nAChR antagonism as a potential therapeutic strategy for relief of negative affect and anxiety.
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Affiliation(s)
- Shawn M. Anderson
- Department of Pharmacology and Toxicology, Virginia Commonwealth University School of Medicine, Richmond, Virginia, United States of America
| | - Darlene H. Brunzell
- Department of Pharmacology and Toxicology, Virginia Commonwealth University School of Medicine, Richmond, Virginia, United States of America
- Interdepartmental Neuroscience Graduate Program, and Institute for Drug and Alcohol Studies, Virginia Commonwealth University School of Medicine, Richmond, Virginia, United States of America
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Yu LF, Eaton JB, Fedolak A, Zhang HK, Hanania T, Brunner D, Lukas RJ, Kozikowski AP. Discovery of highly potent and selective α4β2-nicotinic acetylcholine receptor (nAChR) partial agonists containing an isoxazolylpyridine ether scaffold that demonstrate antidepressant-like activity. Part II. J Med Chem 2012; 55:9998-10009. [PMID: 23092294 DOI: 10.1021/jm301177j] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
In our continued efforts to develop α4β2-nicotinic acetylcholine receptor (nAChR) partial agonists as novel antidepressants having a unique mechanism of action, structure-activity relationship (SAR) exploration of certain isoxazolylpyridine ethers is presented. In particular, modifications to both the azetidine ring present in the starting structure 4 and its metabolically liable hydroxyl side chain substituent have been explored to improve compound druggability. The pharmacological characterization of all new compounds has been carried out using [(3)H]epibatidine binding studies together with functional assays based on (86)Rb(+) ion flux measurements. We found that the deletion of the metabolically liable hydroxyl group or its replacement by a fluoromethyl group not only maintained potency and selectivity but also resulted in compounds showing antidepressant-like properties in the mouse forced swim test. These isoxazolylpyridine ethers appear to represent promising lead candidates in the design of innovative chemical tools containing reporter groups for imaging purposes and of possible therapeutics.
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Affiliation(s)
- Li-Fang Yu
- Drug Discovery Program, Department of Medicinal Chemistry and Pharmacognosy, University of Illinois at Chicago, 833 South Wood Street, Chicago, Illinois 60612, USA
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61
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Hussmann GP, Kellar KJ. A new radioligand binding assay to measure the concentration of drugs in rodent brain ex vivo. J Pharmacol Exp Ther 2012; 343:434-40. [PMID: 22899751 DOI: 10.1124/jpet.112.198069] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023] Open
Abstract
We have developed a new radioligand binding assay method to measure the concentration of nonradiolabeled drugs in the brain ex vivo. This new method fuses the concepts of standard competition and saturation binding assays and uses a transformed version of the Cheng-Prusoff equation (Biochem Pharmacol 22:3099-3108, 1973) to calculate the drug concentration. After testing the validity of this method, we demonstrated its utility by measuring the brain concentration of sazetidine-A, a newly developed nicotinic receptor ligand, and its elimination rate after a single subcutaneous administration. Our results indicate that sazetidine-A reaches brain concentrations that are known to occupy and desensitize the majority of neuronal nicotinic acetylcholine receptor binding sites. Furthermore, using this method, we estimated the half-life of sazetidine-A in the rat brain to be ∼65 min. It is important to note that the method described here to measure sazetidine-A in brain should be generalizable to other drugs acting at any receptor that can be reliably measured with a radiolabeled ligand.
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Affiliation(s)
- G Patrick Hussmann
- Department of Pharmacology and Physiology, Georgetown University School of Medicine, Medical-Dental Building, 3900 Reservoir Road, NW, Washington, DC 20057, USA
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62
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Hussmann GP, Turner JR, Lomazzo E, Venkatesh R, Cousins V, Xiao Y, Yasuda RP, Wolfe BB, Perry DC, Rezvani AH, Levin ED, Blendy JA, Kellar KJ. Chronic sazetidine-A at behaviorally active doses does not increase nicotinic cholinergic receptors in rodent brain. J Pharmacol Exp Ther 2012; 343:441-50. [PMID: 22899752 DOI: 10.1124/jpet.112.198085] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
Chronic nicotine administration increases α4β2 neuronal nicotinic acetylcholine receptor (nAChR) density in brain. This up-regulation probably contributes to the development and/or maintenance of nicotine dependence. nAChR up-regulation is believed to be triggered at the ligand binding site, so it is not surprising that other nicotinic ligands also up-regulate nAChRs in the brain. These other ligands include varenicline, which is currently used for smoking cessation therapy. Sazetidine-A (saz-A) is a newer nicotinic ligand that binds with high affinity and selectivity at α4β2* nAChRs. In behavioral studies, saz-A decreases nicotine self-administration and increases performance on tasks of attention. We report here that, unlike nicotine and varenicline, chronic administration of saz-A at behaviorally active and even higher doses does not up-regulate nAChRs in rodent brains. We used a newly developed method involving radioligand binding to measure the concentrations and nAChR occupancy of saz-A, nicotine, and varenicline in brains from chronically treated rats. Our results indicate that saz-A reached concentrations in the brain that were ∼150 times its affinity for α4β2* nAChRs and occupied at least 75% of nAChRs. Thus, chronic administration of saz-A did not up-regulate nAChRs despite it reaching brain concentrations that are known to bind and desensitize virtually all α4β2* nAChRs in brain. These findings reinforce a model of nicotine addiction based on desensitization of up-regulated nAChRs and introduce a potential new strategy for smoking cessation therapy in which drugs such as saz-A can promote smoking cessation without maintaining nAChR up-regulation, thereby potentially increasing the rate of long-term abstinence from nicotine.
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Affiliation(s)
- G Patrick Hussmann
- Department of Pharmacology and Physiology, Georgetown University School of Medicine, 3900 Reservoir Road, NW, Washington, DC 20057, USA
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AlSharari SD, Carroll FI, McIntosh JM, Damaj MI. The antinociceptive effects of nicotinic partial agonists varenicline and sazetidine-A in murine acute and tonic pain models. J Pharmacol Exp Ther 2012; 342:742-9. [PMID: 22678099 DOI: 10.1124/jpet.112.194506] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Nicotinic agonists display a wide-range profile of antinociceptive activity in acute, tonic, and chronic pain models. However, their effectiveness is limited by their unacceptable side effects. We investigated the antinociceptive effects of two new α4β2* nicotinic partial agonists, varenicline and sazetidine-A, in acute thermal and tonic pain mouse models. Both drugs failed to induce significant effects in the tail-flick and hot-plate tests after subcutaneous administration. However, they blocked nicotine's effects in these tests at very low doses. In contrast to acute pain tests, varenicline and sazetidine-A dose-dependently induced an analgesic effect in the mouse formalin test after systemic administration. Their antinociceptive effects were mediated, however, by different nicotinic acetylcholine receptor (nAChR) subtypes. Sazetidine-A effects were mediated by β2* nAChR subtypes, whereas varenicline actions were attributed to α3β4 nAChRs. Moreover, low inactive doses of varenicline blocked nicotine's actions in phase II of the formalin test. Overall, our results suggest that the antagonistic actions of varenicline at low doses are mediated by β2*-nAChRs and at higher doses as an agonist by α3β4*-nAChRs. In contrast, both actions of sazetidine-A are mediated by β2*-nAChR subtypes. These results suggest that nicotinic partial agonists possess analgesic effects in a rodent tonic pain model and may provide a potential treatment for the treatment of chronic pain disorders.
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Affiliation(s)
- Shakir D AlSharari
- Department of Pharmacology and Toxicology, Virginia Commonwealth University Medical Center, Richmond, Virginia, USA
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64
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Philip NS, Carpenter LL, Tyrka AR, Price LH. The nicotinic acetylcholine receptor as a target for antidepressant drug development. ScientificWorldJournal 2012; 2012:104105. [PMID: 22619570 PMCID: PMC3349306 DOI: 10.1100/2012/104105] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2012] [Accepted: 02/28/2012] [Indexed: 11/17/2022] Open
Abstract
An important new area of antidepressant drug development involves targeting the nicotinic acetylcholine receptor (nAChR). This receptor, which is distributed widely in regions of the brain associated with depression, is also implicated in other important processes that are relevant to depression, such as stress and inflammation. The two classes of drugs that target nAChRs can be broadly divided into mecamylamine- and cytisine-based compounds. These drugs probably exert their effects via antagonism at α4β2 nAChRs, and strong preclinical data support the antidepressant efficacy of both classes when used in conjunction with other primary antidepressants (e.g., monoamine reuptake inhibitors). Although clinical data remain limited, preliminary results in this area constitute a compelling argument for further evaluation of the nAChR as a target for future antidepressant drug development.
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Affiliation(s)
- Noah S Philip
- Mood Disorders Research Program, Butler Hospital and Department of Psychiatry and Human Behavior, Alpert Medical School of Brown University, Providence, RI 02906, USA. Philip, noah
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Ortiz NC, O'Neill HC, Marks MJ, Grady SR. Varenicline blocks β2*-nAChR-mediated response and activates β4*-nAChR-mediated responses in mice in vivo. Nicotine Tob Res 2012; 14:711-9. [PMID: 22241831 DOI: 10.1093/ntr/ntr284] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
Abstract
INTRODUCTION The smoking cessation aid, varenicline, has higher affinity for the alpha4beta2-subtype of the nicotinic acetylcholine receptor (α4β2*-nAChR) than for other subtypes of nAChRs by in vitro assays. The mechanism of action of acute varenicline was studied in vivo to determine (a) subtype activation associated with physiological effects and (b) dose relationship as an antagonist of nicotine. METHODS Acute doses of saline, nicotine, and varenicline were given to mice, and locomotor depression and hypothermia were measured. Subunit null mutant mice as well as selective antagonists were used to study mode of action of varenicline as an agonist. Varenicline as an antagonist of nicotine was also investigated. RESULTS Varenicline evokes locomotor depression and hypothermia at higher doses than necessary for nicotine. Null mutation of the α7- or β2-nAChR subunit did not decrease the effectiveness of varenicline; however, null mutation of the β4 subunit significantly decreased the magnitude of the varenicline effect. Effects of the highest dose studied were blocked by mecamylamine (general nAChR antagonist) and partially antagonized by hexamethonium (largely peripheral nAChR antagonist). No significant block was seen with ondansetron antagonist of 5-hydroxytryptamine 3 receptor. Using a dose of nicotine selective for β2*-nAChR subtype effects with these tests, dose-dependent antagonism by varenicline was seen. Effective inhibitory doses were determined and appear to be in a range consistent with binding affinity or desensitization of β2*-nAChRs. CONCLUSIONS Varenicline acts as a functional antagonist of β2*-nAChRs, blocking certain effects of nicotine. At higher doses, varenicline is an agonist of β4*-nAChRs producing physiological changes in mice.
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Affiliation(s)
- Nick C Ortiz
- Institute for Behavioral Genetics, University of Colorado, Boulder, CO 80309, USA
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66
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Zhang H, Tückmantel W, Eaton JB, Yuen PW, Yu LF, Bajjuri KM, Fedolak A, Wang D, Ghavami A, Caldarone B, Paterson NE, Lowe DA, Brunner D, Lukas RJ, Kozikowski AP. Chemistry and behavioral studies identify chiral cyclopropanes as selective α4β2-nicotinic acetylcholine receptor partial agonists exhibiting an antidepressant profile. J Med Chem 2012; 55:717-24. [PMID: 22171543 DOI: 10.1021/jm201157c] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023]
Abstract
Despite their discovery in the early 20th century and intensive study over the last 20 years, nicotinic acetylcholine receptors (nAChRs) are still far from being well understood. Only a few chemical entities targeting nAChRs are currently undergoing clinical trials, and even fewer have reached the marketplace. In our efforts to discover novel and truly selective nAChR ligands, we designed and synthesized a series of chiral cyclopropane-containing α4β2-specific ligands that display low nanomolar binding affinities and excellent subtype selectivity while acting as partial agonists at α4β2-nAChRs. Their favorable antidepressant-like properties were demonstrated in the classical mouse forced swim test. Preliminary ADMET studies and broad screening toward other common neurotransmitter receptors were also carried out to further evaluate their safety profile and eliminate their potential off-target activity. These highly potent cyclopropane ligands possess superior subtype selectivity compared to other α4β2-nAChR agonists reported to date, including the marketed drug varenicline, and therefore may fully satisfy the crucial prerequisite for avoiding adverse side effects. These novel chemical entities could potentially be advanced to the clinic as new drug candidates for treating depression.
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Affiliation(s)
- Hankun Zhang
- Drug Discovery Program, Department of Medicinal Chemistry and Pharmacognosy, University of Illinois at Chicago, 833 South Wood Street, Chicago, Illinois 60612, United States
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Tsai SJ, Yeh HL, Hong CJ, Liou YJ, Yang AC, Liu ME, Hwang JP. Association ofCHRNA4polymorphism with depression and loneliness in elderly males. GENES BRAIN AND BEHAVIOR 2011; 11:230-4. [DOI: 10.1111/j.1601-183x.2011.00741.x] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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Roni MA, Rahman S. Neuronal nicotinic receptor antagonist reduces anxiety-like behavior in mice. Neurosci Lett 2011. [DOI: https://doi.org/10.1016/j.neulet.2011.09.035] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
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Liu J, Yu LF, Eaton JB, Caldarone B, Cavino K, Ruiz C, Terry M, Fedolak A, Wang D, Ghavami A, Lowe DA, Brunner D, Lukas RJ, Kozikowski AP. Discovery of isoxazole analogues of sazetidine-A as selective α4β2-nicotinic acetylcholine receptor partial agonists for the treatment of depression. J Med Chem 2011; 54:7280-8. [PMID: 21905669 DOI: 10.1021/jm200855b] [Citation(s) in RCA: 59] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
Depression, a common neurological condition, is one of the leading causes of disability and suicide worldwide. Standard treatment, targeting monoamine transporters selective for the neurotransmitters serotonin and noradrenaline, is not able to help many patients that are poor responders. This study advances the development of sazetidine-A analogues that interact with α4β2 nicotinic acetylcholine receptors (nAChRs) as partial agonists and that possess favorable antidepressant profiles. The resulting compounds that are highly selective for the α4β2 subtype of nAChR over α3β4-nAChRs are partial agonists at the α4β2 subtype and have excellent antidepressant behavioral profiles as measured by the mouse forced swim test. Preliminary absorption, distribution, metabolism, excretion, and toxicity (ADMET) studies for one promising ligand revealed an excellent plasma protein binding (PPB) profile, low CYP450-related metabolism, and low cardiovascular toxicity, suggesting it is a promising lead as well as a drug candidate to be advanced through the drug discovery pipeline.
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Affiliation(s)
- Jianhua Liu
- Drug Discovery Program, Department of Medicinal Chemistry and Pharmacognosy, University of Illinois at Chicago, 833 South Wood Street, Chicago, Illinois 60612, United States
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Roni MA, Rahman S. Neuronal nicotinic receptor antagonist reduces anxiety-like behavior in mice. Neurosci Lett 2011; 504:237-41. [PMID: 21964392 DOI: 10.1016/j.neulet.2011.09.035] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2011] [Revised: 09/13/2011] [Accepted: 09/16/2011] [Indexed: 10/17/2022]
Abstract
Brain cholinergic neurotransmission has been implicated in the modulation of anxiety in humans and evidence suggests that drugs targeting neuronal nicotinic acetylcholine receptor (nAChR) could have potential for the treatment of anxiety. The objective of present study was to examine anxiolytic effects of lobeline (0.04 or 0.1 mg/kg), a nAChR antagonist, in C57BL/6J mice using elevated plus-maze (EPM) and marble-burying test. Lobeline (0.04 mg/kg) significantly increased open arm time on EPM and reduced number of marbles buried. Similarly, mecamylamine (0.3 mg/kg) produced anxiolytic effects, while peripherally acting hexamethonium (0.3 mg/kg) failed to produce any response. These results provide evidence that lobeline has anxiolytic potential and nAChR antagonists may represent a new class of anxiolytics in humans.
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Affiliation(s)
- Monzurul Amin Roni
- Department of Pharmaceutical Sciences, College of Pharmacy, South Dakota State University, Brookings, SD 57007, USA
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71
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Caldarone BJ, Wang D, Paterson NE, Manzano M, Fedolak A, Cavino K, Kwan M, Hanania T, Chellappan SK, Kozikowski AP, Olivier B, Picciotto MR, Ghavami A. Dissociation between duration of action in the forced swim test in mice and nicotinic acetylcholine receptor occupancy with sazetidine, varenicline, and 5-I-A85380. Psychopharmacology (Berl) 2011; 217:199-210. [PMID: 21487659 PMCID: PMC3266849 DOI: 10.1007/s00213-011-2271-y] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/10/2010] [Accepted: 03/16/2011] [Indexed: 11/27/2022]
Abstract
RATIONALE Nicotinic acetylcholine receptor (nAChR) agonists, partial agonists, and antagonists have antidepressant-like effects in rodents and reduce symptoms of depression in humans. OBJECTIVES The study determined whether the antidepressant-like effect of the nAChR β2* partial agonist sazetidine-A (sazetidine) in the forced swim test was due to activation or desensitization of β2* nAChRs. The study also determined if sazetidine's behavioral responses in the forced swim test corresponded to β2* nAChRs receptor occupancy and drug bioavailability. RESULTS Acute antidepressant-like effects in the forced swim test were seen with sazetidine and the full β2* agonist 5-I-A8350 (BALB/cJ mice) and the less selective β2* partial agonist varenicline in C57BL/6J but not BALB/cJ mice. The role of β2* nAChRs was confirmed by results showing: (1) reversal of sazetidine's antidepressant-like effects in the forced swim test by nAChR antagonists mecamylamine and dihydro-β-erythroidine; (2) absence of sazetidine's effect in mice lacking the β2 subunit of the nAChR; and (3) a high correspondence between behaviorally active doses of sazetidine and β2* receptor occupancy. β2* receptor occupancy following acute sazetidine, varenicline, and 5-I-A8350 lasted beyond the duration of action in the forced swim test. Sazetidine's long lasting receptor occupancy did not diminish behavioral efficacy in the forced swim test following repeated dosing. CONCLUSIONS Results demonstrate that activation of a small population of β2* nAChRs (10-40%) is sufficient to elicit sazetidine's antidepressant-like actions without producing tolerance and suggest that ligands that activate β2* nAChRs would be promising targets for the development of a new class of antidepressant.
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Affiliation(s)
| | - Daguang Wang
- PsychoGenics, Inc. 765 Old Saw Mill River Rd., Tarrytown, NY 10591
| | - Neil E. Paterson
- PsychoGenics, Inc. 765 Old Saw Mill River Rd., Tarrytown, NY 10591
| | - Michael Manzano
- PsychoGenics, Inc. 765 Old Saw Mill River Rd., Tarrytown, NY 10591
| | - Allison Fedolak
- PsychoGenics, Inc. 765 Old Saw Mill River Rd., Tarrytown, NY 10591
| | - Katie Cavino
- PsychoGenics, Inc. 765 Old Saw Mill River Rd., Tarrytown, NY 10591
| | - Mei Kwan
- PsychoGenics, Inc. 765 Old Saw Mill River Rd., Tarrytown, NY 10591
| | - Taleen Hanania
- PsychoGenics, Inc. 765 Old Saw Mill River Rd., Tarrytown, NY 10591
| | - Sheela K. Chellappan
- Department of Medicinal Chemistry and Pharmacognosy University of Illinois at Chicago
| | - Alan P. Kozikowski
- Department of Medicinal Chemistry and Pharmacognosy University of Illinois at Chicago
| | - Berend Olivier
- Department of Pharmacology, Utrecht Institute for Pharmaceutical Sciences, and Rudolf Magnus Institute of Neuroscience, Utrecht University, Utrecht, The Netherlands,Department of Psychiatry, Yale School of Medicine, 34 Park Street, 3rd Floor Research, New Haven, CT 06508
| | - Marina R. Picciotto
- Department of Psychiatry, Yale School of Medicine, 34 Park Street, 3rd Floor Research, New Haven, CT 06508
| | - Afshin Ghavami
- PsychoGenics, Inc. 765 Old Saw Mill River Rd., Tarrytown, NY 10591
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Graef S, Schönknecht P, Sabri O, Hegerl U. Cholinergic receptor subtypes and their role in cognition, emotion, and vigilance control: an overview of preclinical and clinical findings. Psychopharmacology (Berl) 2011; 215:205-29. [PMID: 21212938 DOI: 10.1007/s00213-010-2153-8] [Citation(s) in RCA: 70] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/15/2010] [Accepted: 12/15/2010] [Indexed: 01/10/2023]
Abstract
RATIONALE The cholinergic system has long been linked to cognitive processes. Two main classes of acetylcholine (ACh) receptors exist in the human brain, namely muscarinic and nicotinic receptors, of which several subtypes occur. OBJECTIVES This review seeks to provide an overview of previous findings on the influence of cholinergic receptor manipulations on cognition in animals and humans, with particular emphasis on the role of selected cholinergic receptor subtypes. Furthermore, the involvement of these receptor subtypes in the regulation of emotion and brain electrical activity as measured by electroencephalography (EEG) shall be addressed since these domains are considered to be important modulators of cognitive functioning. RESULTS In regard to cognition, the muscarinic receptor subtypes have been implicated mainly in memory functions, but have also been linked to attentional processes. The nicotinic α7 receptor subtype is involved in working memory, whereas the α4β2* subtype has been linked to tests of attention. Both muscarinic and nicotinic cholinergic mechanisms play a role in modulating brain electrical activity. Nicotinic receptors have been strongly associated with the modulation of depression and anxiety. CONCLUSIONS Cholinergic receptor manipulations have an effect on cognition, emotion, and brain electrical activity as measured by EEG. Changes in cognition can result from direct cholinergic receptor manipulation or from cholinergically induced changes in vigilance or affective state.
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Affiliation(s)
- Susanne Graef
- Department of Psychiatry, University of Leipzig, Semmelweisstr. 10, 04103 Leipzig, Germany.
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Onksen JL, Brown EJ, Blendy JA. Selective deletion of a cell cycle checkpoint kinase (ATR) reduces neurogenesis and alters responses in rodent models of behavioral affect. Neuropsychopharmacology 2011; 36:960-9. [PMID: 21248719 PMCID: PMC3077265 DOI: 10.1038/npp.2010.234] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/18/2023]
Abstract
Hippocampal function has been implicated in mood and anxiety disorders, as well as in the response to antidepressant (AD) treatment. However, the significance of new neurons in the therapeutic mechanism of ADs remains unclear. In this study, the proliferation of new neurons was inhibited through conditional deletion of ataxia telangeictasia-mutated and rad-3 related (ATR), a cell cycle checkpoint kinase, and cellular and behavioral outcomes following AD exposure were evaluated. ATR was conditionally deleted by microinjecting a Cre recombinase-expressing virus into the hippocampus of floxed-ATR mice. Behavioral assessment in multiple rodent models of affective state revealed anxiolytic-like behavior in the elevated zero maze, marble burying test, and novelty-induced hypophagia (NIH) test. The efficacy of chronic desipramine (DMI) treatment was evaluated in the NIH test, as this paradigm is thought to be sensitive to increases in neurogenesis by chronic AD exposure. Chronic exposure to DMI reduced hyponeophagia in the NIH test in control mice, whereas DMI had no behavioral effect in ATR-deleted mice. Although DMI did not alter cell proliferation in either group, it did produce a robust increase in dendritic spine density in control mice, indicative of enhanced neuronal plasticity. This effect of DMI on spine density was severely attenuated following ATR deletion. These findings demonstrate that reductions in basal neurogenesis produce an anxiolytic phenotype and reduce AD efficacy in behaviors requiring chronic exposure. Furthermore, attenuated capacity for synaptic remodeling may underlie these behaviors. ATR deletion may serve as a valuable model to study the various proposed roles of newborn neurons in the hippocampus.
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Affiliation(s)
- Jennifer L Onksen
- Department of Pharmacology, University of Pennsylvania School of Medicine, Philadelphia, PA, USA
| | - Eric J Brown
- Department of Cancer Biology, University of Pennsylvania School of Medicine, Philadelphia, PA, USA
| | - Julie A Blendy
- Department of Pharmacology, University of Pennsylvania School of Medicine, Philadelphia, PA, USA,Department of Pharmacology, University of Pennsylvania School of Medicine, Philadelphia, PA 19104, USA. Tel: +215 898 0730, Fax: +215 573 2041, E-mail:
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Mineur YS, Picciotto MR. Nicotine receptors and depression: revisiting and revising the cholinergic hypothesis. Trends Pharmacol Sci 2010; 31:580-6. [PMID: 20965579 PMCID: PMC2991594 DOI: 10.1016/j.tips.2010.09.004] [Citation(s) in RCA: 200] [Impact Index Per Article: 14.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2010] [Revised: 09/20/2010] [Accepted: 09/21/2010] [Indexed: 12/15/2022]
Abstract
There is a well-established connection between smoking and depression. Depressed individuals are over-represented among smokers, and ex-smokers often experience increased depressive symptoms immediately after stopping smoking. Nicotine in tobacco binds, activates and desensitizes nicotinic acetylcholine receptors (nAChRs), but it is not known whether activation or desensitization is more important for the effects of nicotine on depressive symptoms. Here we review, based on clinical and preclinical studies of nicotinic drugs, the hypothesis that blockade (rather than activation) of neuronal nAChRs might be important for the effects of nicotinic agents on depressive symptoms. The endogenous neurotransmitter for nAChRs is acetylcholine, and the effects of nicotine on depression-like behaviors support the idea that dysregulation of the cholinergic system might contribute to the etiology of major depressive disorder. Thus, pharmacological agents that limit acetylcholine signaling through neuronal nAChRs might be promising for the development of novel antidepressant medications.
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Affiliation(s)
- Yann S. Mineur
- Department of Psychiatry, Yale University School of Medicine, 34 Park Street, 3 Floor Research, New Haven, CT 06508, USA
| | - Marina R. Picciotto
- Department of Psychiatry, Yale University School of Medicine, 34 Park Street, 3 Floor Research, New Haven, CT 06508, USA
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Turner JR, Castellano LM, Blendy JA. Parallel anxiolytic-like effects and upregulation of neuronal nicotinic acetylcholine receptors following chronic nicotine and varenicline. Nicotine Tob Res 2010; 13:41-6. [PMID: 21097981 DOI: 10.1093/ntr/ntq206] [Citation(s) in RCA: 70] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
INTRODUCTION Clinical and preclinical studies suggest that regulation of nicotinic acetylcholine receptors (nAChR) maybe involved in the etiology of withdrawal symptoms. METHODS We evaluated heteromeric nAChR regulation via [³H]epibatidine binding following cessation of chronic nicotine or varenicline treatment. Animals were concurrently tested in the marble-burying test to evaluate treatment-related effects. RESULTS We found that both nicotine (18 mg/kg/day, free base) and varenicline (1.8 mg/kg/day) chronically administered for 14 days upregulated nAChRs significantly in the cortex, hippocampus, striatum, and thalamus. The duration of upregulation (up to 72 hr) was both drug and region specific. In addition to nAChR upregulation, chronic administration of both nicotine and varenicline had anxiolytic-like effects in the marble-burying test. This effect was maintained for 48 hr following cessation of varenicline but was absent 24 hr following cessation from nicotine. Additionally, marble-burying behavior positively correlated to the regulation of cortical nAChRs following cessation of either treatment. CONCLUSIONS Varenicline has been shown to be an efficacious smoking cessation aid, with a proposed mechanism of action that includes modulation of dopamine release in reward areas of the brain. Our studies show that varenicline elicits both anxiolytic effects in the marble-burying test as well as region- and time-specific receptor upregulation. These findings suggest receptor upregulation as a mechanism for its efficacy as a smoking cessation therapy.
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Affiliation(s)
- Jill R Turner
- Department of Pharmacology, University of Pennsylvania, Philadelphia, PA, USA
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