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Quantification of receptor binding from response data obtained at different receptor levels: a simple individual sigmoid fitting and a unified SABRE approach. Sci Rep 2022; 12:18833. [PMID: 36336760 PMCID: PMC9637741 DOI: 10.1038/s41598-022-23588-w] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2022] [Accepted: 11/02/2022] [Indexed: 11/07/2022] Open
Abstract
Methods that allow quantification of receptor binding (occupancy) by measuring response (effect) data only are of interest as they can be used to allow characterization of binding properties (e.g., dissociation constant, Kd) without having to perform explicit ligand binding experiments that require different setups (e.g., use of labeled ligands). However, since response depends not just on the binding affinity-determined receptor occupancy, but also on receptor activation, which is affected by ligand efficacy (plus constitutive activity, if present), and downstream pathway amplification, this requires the acquisition and fitting of multiple concentration-response data. Here, two alternative methods, which both are straightforward to implement using nonlinear regression software, are described to fit such multiple responses measured at different receptor levels that can be obtained, for example, by partial irreversible receptor inactivation (i.e., Furchgott method) or different expression levels. One is a simple method via straightforward fitting of each response with sigmoid functions and estimation of Kd from the obtained Emax and EC50 values as Kd = (Emax·EC'50 - E'max·EC50)/(Emax - E'max). This is less error-prone than the original Furchgott method of double-reciprocal fit and simpler than alternatives that require concentration interpolations, thus, should allow more widespread use of this so-far underutilized approach to estimate binding properties. Relative efficacies can then be compared using Emax·Kd/EC50 values. The other is a complex method that uses the SABRE receptor model to obtain a unified fit of the multiple concentration-response curves with a single set of parameters that include binding affinity Kd, efficacy ε, amplification γ, and Hill coefficient n. Illustrations with simulated and experimental data are presented including with activity data of three muscarinic agonists measured in rabbit myocardium.
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2
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Brown AJH, Bradley SJ, Marshall FH, Brown GA, Bennett KA, Brown J, Cansfield JE, Cross DM, de Graaf C, Hudson BD, Dwomoh L, Dias JM, Errey JC, Hurrell E, Liptrot J, Mattedi G, Molloy C, Nathan PJ, Okrasa K, Osborne G, Patel JC, Pickworth M, Robertson N, Shahabi S, Bundgaard C, Phillips K, Broad LM, Goonawardena AV, Morairty SR, Browning M, Perini F, Dawson GR, Deakin JFW, Smith RT, Sexton PM, Warneck J, Vinson M, Tasker T, Tehan BG, Teobald B, Christopoulos A, Langmead CJ, Jazayeri A, Cooke RM, Rucktooa P, Congreve MS, Weir M, Tobin AB. From structure to clinic: Design of a muscarinic M1 receptor agonist with potential to treatment of Alzheimer's disease. Cell 2021; 184:5886-5901.e22. [PMID: 34822784 DOI: 10.1016/j.cell.2021.11.001] [Citation(s) in RCA: 34] [Impact Index Per Article: 11.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2020] [Revised: 04/29/2021] [Accepted: 11/01/2021] [Indexed: 12/31/2022]
Abstract
Current therapies for Alzheimer's disease seek to correct for defective cholinergic transmission by preventing the breakdown of acetylcholine through inhibition of acetylcholinesterase, these however have limited clinical efficacy. An alternative approach is to directly activate cholinergic receptors responsible for learning and memory. The M1-muscarinic acetylcholine (M1) receptor is the target of choice but has been hampered by adverse effects. Here we aimed to design the drug properties needed for a well-tolerated M1-agonist with the potential to alleviate cognitive loss by taking a stepwise translational approach from atomic structure, cell/tissue-based assays, evaluation in preclinical species, clinical safety testing, and finally establishing activity in memory centers in humans. Through this approach, we rationally designed the optimal properties, including selectivity and partial agonism, into HTL9936-a potential candidate for the treatment of memory loss in Alzheimer's disease. More broadly, this demonstrates a strategy for targeting difficult GPCR targets from structure to clinic.
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Affiliation(s)
- Alastair J H Brown
- Sosei-Heptares, Steinmetz Building, Granta Park, Cambridge, CB21 6DG, UK
| | - Sophie J Bradley
- Sosei-Heptares, Steinmetz Building, Granta Park, Cambridge, CB21 6DG, UK; The Centre for Translational Pharmacology, Institute of Molecular, Cell and Systems Biology, College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow, G12 8QQ, UK
| | - Fiona H Marshall
- Sosei-Heptares, Steinmetz Building, Granta Park, Cambridge, CB21 6DG, UK
| | - Giles A Brown
- Sosei-Heptares, Steinmetz Building, Granta Park, Cambridge, CB21 6DG, UK
| | - Kirstie A Bennett
- Sosei-Heptares, Steinmetz Building, Granta Park, Cambridge, CB21 6DG, UK
| | - Jason Brown
- Sosei-Heptares, Steinmetz Building, Granta Park, Cambridge, CB21 6DG, UK
| | - Julie E Cansfield
- Sosei-Heptares, Steinmetz Building, Granta Park, Cambridge, CB21 6DG, UK
| | - David M Cross
- Sosei-Heptares, Steinmetz Building, Granta Park, Cambridge, CB21 6DG, UK; Cross Pharma Consulting Ltd, 20-22 Wenlock Road, London, N17GU, UK
| | - Chris de Graaf
- Sosei-Heptares, Steinmetz Building, Granta Park, Cambridge, CB21 6DG, UK
| | - Brian D Hudson
- Sosei-Heptares, Steinmetz Building, Granta Park, Cambridge, CB21 6DG, UK
| | - Louis Dwomoh
- The Centre for Translational Pharmacology, Institute of Molecular, Cell and Systems Biology, College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow, G12 8QQ, UK
| | - João M Dias
- Sosei-Heptares, Steinmetz Building, Granta Park, Cambridge, CB21 6DG, UK
| | - James C Errey
- Sosei-Heptares, Steinmetz Building, Granta Park, Cambridge, CB21 6DG, UK
| | - Edward Hurrell
- Sosei-Heptares, Steinmetz Building, Granta Park, Cambridge, CB21 6DG, UK
| | - Jan Liptrot
- Sosei-Heptares, Steinmetz Building, Granta Park, Cambridge, CB21 6DG, UK
| | - Giulio Mattedi
- Sosei-Heptares, Steinmetz Building, Granta Park, Cambridge, CB21 6DG, UK
| | - Colin Molloy
- The Centre for Translational Pharmacology, Institute of Molecular, Cell and Systems Biology, College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow, G12 8QQ, UK
| | - Pradeep J Nathan
- Sosei-Heptares, Steinmetz Building, Granta Park, Cambridge, CB21 6DG, UK; Brain Mapping Unit, University of Cambridge, Department of Psychiatry, Herchel Smith Building, Cambridge, CB20SZ, UK
| | - Krzysztof Okrasa
- Sosei-Heptares, Steinmetz Building, Granta Park, Cambridge, CB21 6DG, UK
| | - Greg Osborne
- Sosei-Heptares, Steinmetz Building, Granta Park, Cambridge, CB21 6DG, UK
| | - Jayesh C Patel
- Sosei-Heptares, Steinmetz Building, Granta Park, Cambridge, CB21 6DG, UK
| | - Mark Pickworth
- Sosei-Heptares, Steinmetz Building, Granta Park, Cambridge, CB21 6DG, UK
| | - Nathan Robertson
- Sosei-Heptares, Steinmetz Building, Granta Park, Cambridge, CB21 6DG, UK
| | - Shahram Shahabi
- Eli Lilly & Co, Neuroscience Discovery, Erl Wood Manor, Windlesham, Surrey, GU20 6PH, UK
| | - Christoffer Bundgaard
- Eli Lilly & Co, Neuroscience Discovery, Erl Wood Manor, Windlesham, Surrey, GU20 6PH, UK; H. Lundbeck A/S, Neuroscience Research, Ottiliavej 9, 2500 Valby, Copenhagen, Denmark
| | - Keith Phillips
- Eli Lilly & Co, Neuroscience Discovery, Erl Wood Manor, Windlesham, Surrey, GU20 6PH, UK
| | - Lisa M Broad
- Eli Lilly & Co, Neuroscience Discovery, Erl Wood Manor, Windlesham, Surrey, GU20 6PH, UK
| | - Anushka V Goonawardena
- Center for Neuroscience, Biosciences Division, SRI International, 333 Ravenswood Avenue, Menlo Park, CA 94025, USA
| | - Stephen R Morairty
- Center for Neuroscience, Biosciences Division, SRI International, 333 Ravenswood Avenue, Menlo Park, CA 94025, USA
| | - Michael Browning
- University Department of Psychiatry, University of Oxford, Warneford Hospital, Oxford, OX12JD, UK; P1vital, Manor house, Howbery Buisness Park, Wallingford, OX108BA, UK
| | - Francesca Perini
- Centre for Cognitive Neuroscience - Duke-NUS Medical School, 8 College Road, 169857, Singapore
| | - Gerard R Dawson
- University Department of Psychiatry, University of Oxford, Warneford Hospital, Oxford, OX12JD, UK
| | - John F W Deakin
- Neuroscience and Psychiatry Unit, University of Manchester, Manchester, M139PT UK
| | - Robert T Smith
- Sosei-Heptares, Steinmetz Building, Granta Park, Cambridge, CB21 6DG, UK
| | - Patrick M Sexton
- Drug Discovery Biology, Monash Institute of Pharmaceutical Sciences and Department of Pharmacology, Monash University, Parkville 3052, Victoria, Australia; ARC Centre for Cryo-electron Microscopy of Membrane Proteins, Monash Institute of Pharmaceutical Sciences, Monash University, Parkville 3052, Victoria, Australia
| | - Julie Warneck
- Protogenia Consulting Ltd, PO-Box 289, Ely, CB79DR, UK
| | - Mary Vinson
- Sosei-Heptares, Steinmetz Building, Granta Park, Cambridge, CB21 6DG, UK
| | - Tim Tasker
- Sosei-Heptares, Steinmetz Building, Granta Park, Cambridge, CB21 6DG, UK
| | - Benjamin G Tehan
- Sosei-Heptares, Steinmetz Building, Granta Park, Cambridge, CB21 6DG, UK
| | - Barry Teobald
- Sosei-Heptares, Steinmetz Building, Granta Park, Cambridge, CB21 6DG, UK
| | - Arthur Christopoulos
- Drug Discovery Biology, Monash Institute of Pharmaceutical Sciences and Department of Pharmacology, Monash University, Parkville 3052, Victoria, Australia
| | - Christopher J Langmead
- Sosei-Heptares, Steinmetz Building, Granta Park, Cambridge, CB21 6DG, UK; Drug Discovery Biology, Monash Institute of Pharmaceutical Sciences and Department of Pharmacology, Monash University, Parkville 3052, Victoria, Australia
| | - Ali Jazayeri
- Sosei-Heptares, Steinmetz Building, Granta Park, Cambridge, CB21 6DG, UK
| | - Robert M Cooke
- Sosei-Heptares, Steinmetz Building, Granta Park, Cambridge, CB21 6DG, UK
| | - Prakash Rucktooa
- Sosei-Heptares, Steinmetz Building, Granta Park, Cambridge, CB21 6DG, UK
| | - Miles S Congreve
- Sosei-Heptares, Steinmetz Building, Granta Park, Cambridge, CB21 6DG, UK
| | - Malcolm Weir
- Sosei-Heptares, Steinmetz Building, Granta Park, Cambridge, CB21 6DG, UK.
| | - Andrew B Tobin
- The Centre for Translational Pharmacology, Institute of Molecular, Cell and Systems Biology, College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow, G12 8QQ, UK.
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3
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Functional approaches to the study of G-protein-coupled receptors in postmortem brain tissue: [ 35S]GTPγS binding assays combined with immunoprecipitation. Pharmacol Rep 2021; 73:1079-1095. [PMID: 33876404 DOI: 10.1007/s43440-021-00253-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2021] [Revised: 03/16/2021] [Accepted: 03/19/2021] [Indexed: 10/21/2022]
Abstract
G-protein-coupled receptors (GPCRs) have an enormous biochemical importance as they bind to diverse extracellular ligands and regulate a variety of physiological and pathological responses. G-protein activation measures the functional consequence of receptor occupancy at one of the earliest receptor-mediated events. Receptor coupling to G-proteins promotes the GDP/GTP exchange on Gα subunits. Thus, modulation of the binding of the poorly hydrolysable GTP analog [35S]GTPγS to the Gα-protein subunit can be used as a functional approach to quantify GPCR interaction with agonist, antagonist or inverse agonist drugs. In order to determine receptor-mediated selective activation of the different Gα-proteins, [35S]GTPγS binding assays combined with immunodetection by specific antibodies have been developed and applied to physiological and pathological brain conditions. Currently, immunoprecipitation with magnetic beads and scintillation proximity assays are the most habitual techniques for this purpose. The present review summarizes the different procedures, advantages and limitations of the [35S]GTPγS binding assays combined with selective Gα-protein sequestration methods. Experience of functional coupling of several GPCRs to different Gα-proteins and recommendations for optimal performance in brain membranes are described. One of the biggest opportunities opened by these techniques is that they enable evaluation of biased agonism in the native tissue, which results in high interest in drug discovery. The available results derived from application of these functional methodologies to study GPCR dysfunctions in neuro-psychiatric disorders are also described. In conclusion, [35S]GTPγS binding combined with antibody-mediated immunodetection represents an useful method to separately evaluate the functional activity of drugs acting on GPCRs over each Gα-protein subtype.
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van der Westhuizen ET, Choy KHC, Valant C, McKenzie-Nickson S, Bradley SJ, Tobin AB, Sexton PM, Christopoulos A. Fine Tuning Muscarinic Acetylcholine Receptor Signaling Through Allostery and Bias. Front Pharmacol 2021; 11:606656. [PMID: 33584282 PMCID: PMC7878563 DOI: 10.3389/fphar.2020.606656] [Citation(s) in RCA: 25] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2020] [Accepted: 11/30/2020] [Indexed: 12/18/2022] Open
Abstract
The M1 and M4 muscarinic acetylcholine receptors (mAChRs) are highly pursued drug targets for neurological diseases, in particular for Alzheimer's disease and schizophrenia. Due to high sequence homology, selective targeting of any of the M1-M5 mAChRs through the endogenous ligand binding site has been notoriously difficult to achieve. With the discovery of highly subtype selective mAChR positive allosteric modulators in the new millennium, selectivity through targeting an allosteric binding site has opened new avenues for drug discovery programs. However, some hurdles remain to be overcome for these promising new drug candidates to progress into the clinic. One challenge is the potential for on-target side effects, such as for the M1 mAChR where over-activation of the receptor by orthosteric or allosteric ligands can be detrimental. Therefore, in addition to receptor subtype selectivity, a drug candidate may need to exhibit a biased signaling profile to avoid such on-target adverse effects. Indeed, recent studies in mice suggest that allosteric modulators for the M1 mAChR that bias signaling toward specific pathways may be therapeutically important. This review brings together details on the signaling pathways activated by the M1 and M4 mAChRs, evidence of biased agonism at these receptors, and highlights pathways that may be important for developing new subtype selective allosteric ligands to achieve therapeutic benefit.
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Affiliation(s)
- Emma T. van der Westhuizen
- Drug Discovery Biology, Monash Institute for Pharmaceutical Research, Monash University, Parkville, VIC, Australia
| | - K. H. Christopher Choy
- Drug Discovery Biology, Monash Institute for Pharmaceutical Research, Monash University, Parkville, VIC, Australia
| | - Celine Valant
- Drug Discovery Biology, Monash Institute for Pharmaceutical Research, Monash University, Parkville, VIC, Australia
| | - Simon McKenzie-Nickson
- Drug Discovery Biology, Monash Institute for Pharmaceutical Research, Monash University, Parkville, VIC, Australia
| | - Sophie J. Bradley
- Centre for Translational Pharmacology, Institute of Molecular Cell and Systems Biology, University of Glasgow, Glasgow, United Kingdom
| | - Andrew B. Tobin
- Centre for Translational Pharmacology, Institute of Molecular Cell and Systems Biology, University of Glasgow, Glasgow, United Kingdom
| | - Patrick M. Sexton
- Drug Discovery Biology, Monash Institute for Pharmaceutical Research, Monash University, Parkville, VIC, Australia
| | - Arthur Christopoulos
- Drug Discovery Biology, Monash Institute for Pharmaceutical Research, Monash University, Parkville, VIC, Australia
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Dyer-Reaves K, Goodman AM, Nelson AR, McMahon LL. Alpha1-Adrenergic Receptor Mediated Long-Term Depression at CA3-CA1 Synapses Can Be Induced via Accumulation of Endogenous Norepinephrine and Is Preserved Following Noradrenergic Denervation. Front Synaptic Neurosci 2019; 11:27. [PMID: 31649525 PMCID: PMC6794465 DOI: 10.3389/fnsyn.2019.00027] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2019] [Accepted: 09/20/2019] [Indexed: 12/27/2022] Open
Abstract
Locus coeruleus (LC) provides the sole source of noradrenergic (NA) innervation to hippocampus, and it undergoes significant degeneration early in Alzheimer's disease (AD). Norepinephrine (NE) modulates synaptic transmission and plasticity at hippocampal synapses which likely contributes to hippocampus-dependent learning and memory. We previously reported that pharmacological activation of α1 adrenergic receptors (α1ARs) induces long-term depression (LTD) at CA3-CA1 synapses. Here, we investigated whether accumulation of endogenous NE via pharmacological blockade of norepinephrine transporters (NETs) and the NE degradative enzyme, monoamine oxidase (MAO), can induce α1AR LTD, as these inhibitors are used clinically. Further, we sought to determine how degeneration of hippocampal NA innervation, as occurs in AD, impacts α1AR function and α1AR LTD. Bath application of NET and MAO inhibitors in slices from control rats reliably induced α1AR LTD when β adrenergic receptors were inhibited. To induce degeneration of LC-NA innervation, rats were treated with the specific NA neurotoxin DSP-4 and recordings performed 1-3 weeks later when NA axon degeneration had stabilized. Even with 85% loss of hippocampal NA innervation, α1AR LTD was successfully induced using either the α1AR agonist phenylephrine or the combined NET and MAO inhibitors, and importantly, the LTD magnitude was not different from saline-treated control. These data suggest that despite significant decreases in NA input to hippocampus, the mechanisms necessary for the induction of α1AR LTD remain functional. Furthermore, we posit that α1AR activation could be a viable therapeutic target for pharmacological intervention in AD and other diseases involving malfunctions of NA neurotransmission.
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Affiliation(s)
- Katie Dyer-Reaves
- Department of Cell, Developmental, and Integrative Biology (CDIB), School of Medicine, University of Alabama at Birmingham, Birmingham, AL, United States
| | - Anthoni M. Goodman
- Department of Cell, Developmental, and Integrative Biology (CDIB), School of Medicine, University of Alabama at Birmingham, Birmingham, AL, United States
- Department of Psychology, University of Alabama at Birmingham, Birmingham, AL, United States
| | - Amy R. Nelson
- Department of Cell, Developmental, and Integrative Biology (CDIB), School of Medicine, University of Alabama at Birmingham, Birmingham, AL, United States
| | - Lori L. McMahon
- Department of Cell, Developmental, and Integrative Biology (CDIB), School of Medicine, University of Alabama at Birmingham, Birmingham, AL, United States
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Hopper S, Pavey GM, Gogos A, Dean B. Widespread Changes in Positive Allosteric Modulation of the Muscarinic M1 Receptor in Some Participants With Schizophrenia. Int J Neuropsychopharmacol 2019; 22:640-650. [PMID: 31428788 PMCID: PMC6822142 DOI: 10.1093/ijnp/pyz045] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/24/2019] [Revised: 07/22/2019] [Accepted: 08/15/2019] [Indexed: 12/15/2022] Open
Abstract
BACKGROUND Preclinical and some human data suggest allosteric modulation of the muscarinic M1 receptor (CHRM1) is a promising approach for the treatment of schizophrenia. However, it is suggested there is a subgroup of participants with schizophrenia who have profound loss of cortical CHRM1 (MRDS). This raises the possibility that some participants with schizophrenia may not respond optimally to CHRM1 allosteric modulation. Here we describe a novel methodology to measure positive allosteric modulation of CHRM1 in human CNS and the measurement of that response in the cortex, hippocampus, and striatum from participants with MRDS, non-MRDS and controls. METHODS The cortex (Brodmann's area 6), hippocampus, and striatum from 40 participants with schizophrenia (20 MRDS and 20 non-MRDS) and 20 controls were used to measure benzyl quinolone carboxylic acid-mediated shift in acetylcholine displacement of [3H]N-methylscopolamine using a novel in situ radioligand binding with autoradiography methodology. RESULTS Compared with controls, participants with schizophrenia had lower levels of specific [3H]N-methylscopolamine binding in all CNS regions, whilst benzyl quinolone carboxylic acid-modulated binding was less in the striatum, Brodmann's area 6, dentate gyrus, and subiculum. When divided by subgroup, only in MRDS was there lower specific [3H]N-methylscopolamine binding and less benzyl quinolone carboxylic acid-modulated binding in all cortical and subcortical regions studied. CONCLUSIONS In a subgroup of participants with schizophrenia, there is a widespread decreased responsiveness to a positive allosteric modulator at the CHRM1. This finding may have ramifications it positive allosteric modulators of the CHRM1 are used in clinical trials to treat schizophrenia as some participants may not have an optimal response.
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Affiliation(s)
- Shaun Hopper
- The Florey Institute of Neuroscience and Mental Health, Parkville, Victoria, Australia,Cooperative Research Centre for Mental Health, Parkville, Victoria, Australia
| | - Geoffrey Mark Pavey
- The Florey Institute of Neuroscience and Mental Health, Parkville, Victoria, Australia
| | - Andrea Gogos
- The Florey Institute of Neuroscience and Mental Health, Parkville, Victoria, Australia
| | - Brian Dean
- The Florey Institute of Neuroscience and Mental Health, Parkville, Victoria, Australia,Cooperative Research Centre for Mental Health, Parkville, Victoria, Australia,The Centre for Mental Health, Swinburne University, Hawthorn, Victoria, Australia,Correspondence: Professor Brian Dean, Head, The Molecular Psychiatry Laboratories, The Florey Institute for Neuroscience and Mental Health, 30 Royal Parade, Parkville, VIC 3010, Australia ()
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Odagaki Y. Guanosine-5′-O-(3-[35S]thio)triphosphate ([35S]GTPγS) Binding/Immunoprecipitation Assay Using Magnetic Beads Coated with Anti-Gα Antibody in Mammalian Brain Membranes. CO-IMMUNOPRECIPITATION METHODS FOR BRAIN TISSUE 2019. [DOI: 10.1007/978-1-4939-8985-0_8] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
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Broad LM, Sanger HE, Mogg AJ, Colvin EM, Zwart R, Evans DA, Pasqui F, Sher E, Wishart GN, Barth VN, Felder CC, Goldsmith PJ. Identification and pharmacological profile of SPP1, a potent, functionally selective and brain penetrant agonist at muscarinic M 1 receptors. Br J Pharmacol 2019; 176:110-126. [PMID: 30276808 PMCID: PMC6284335 DOI: 10.1111/bph.14510] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2018] [Revised: 09/14/2018] [Accepted: 09/18/2018] [Indexed: 11/30/2022] Open
Abstract
BACKGROUND AND PURPOSE We aimed to identify and develop novel, selective muscarinic M1 receptor agonists as potential therapeutic agents for the symptomatic treatment of Alzheimer's disease. EXPERIMENTAL APPROACH We developed and utilized a novel M1 receptor occupancy assay to drive a structure activity relationship in a relevant brain region while simultaneously tracking drug levels in plasma and brain to optimize for central penetration. Functional activity was tracked in relevant native in vitro assays allowing translational (rat-human) benchmarking of structure-activity relationship molecules to clinical comparators. KEY RESULTS Using this paradigm, we identified a series of M1 receptor selective molecules displaying desirable in vitro and in vivo properties and optimized key features, such as central penetration while maintaining selectivity and a partial agonist profile. From these compounds, we selected spiropiperidine 1 (SPP1). In vitro, SPP1 is a potent, partial agonist of cortical and hippocampal M1 receptors with activity conserved across species. SPP1 displays high functional selectivity for M1 receptors over native M2 and M3 receptor anti-targets and over a panel of other targets. Assessment of central target engagement by receptor occupancy reveals SPP1 significantly and dose-dependently occupies rodent cortical M1 receptors. CONCLUSIONS AND IMPLICATIONS We report the discovery of SPP1, a novel, functionally selective, brain penetrant partial orthosteric agonist at M1 receptors, identified by a novel receptor occupancy assay. SPP1 is amenable to in vitro and in vivo study and provides a valuable research tool to further probe the role of M1 receptors in physiology and disease.
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Affiliation(s)
- Lisa M Broad
- Eli Lilly and Company, Lilly Research CentreWindleshamSurreyUK
| | - Helen E Sanger
- Eli Lilly and Company, Lilly Research CentreWindleshamSurreyUK
| | - Adrian J Mogg
- Eli Lilly and Company, Lilly Research CentreWindleshamSurreyUK
| | - Ellen M Colvin
- Eli Lilly and Company, Lilly Research CentreWindleshamSurreyUK
| | - Ruud Zwart
- Eli Lilly and Company, Lilly Research CentreWindleshamSurreyUK
| | - David A Evans
- Eli Lilly and Company, Lilly Research CentreWindleshamSurreyUK
| | | | - Emanuele Sher
- Eli Lilly and Company, Lilly Research CentreWindleshamSurreyUK
| | | | - Vanessa N Barth
- Eli Lilly and Company, Lilly Corporate CenterIndianapolisINUSA
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Moran SP, Cho HP, Maksymetz J, Remke DH, Hanson RM, Niswender CM, Lindsley CW, Rook JM, Conn PJ. PF-06827443 Displays Robust Allosteric Agonist and Positive Allosteric Modulator Activity in High Receptor Reserve and Native Systems. ACS Chem Neurosci 2018; 9:2218-2224. [PMID: 29683646 DOI: 10.1021/acschemneuro.8b00106] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022] Open
Abstract
Positive allosteric modulators (PAMs) of the M1 subtype of muscarinic acetylcholine receptor have attracted intense interest as an exciting new approach for improving the cognitive deficits in schizophrenia and Alzheimer's disease. Recent evidence suggests that the presence of intrinsic agonist activity of some M1 PAMs may reduce efficacy and contribute to adverse effect liability. However, the M1 PAM PF-06827443 was reported to have only weak agonist activity at human M1 receptors but produced M1-dependent adverse effects. We now report that PF-06827443 is an allosteric agonist in cell lines expressing rat, dog, and human M1 and use of inducible cell lines shows that agonist activity of PF-06827443 is dependent on receptor reserve. Furthermore, PF-06827443 is an agonist in native tissue preparations and induces behavioral convulsions in mice similar to other ago-PAMs. These findings suggest that PF-06827443 is a robust ago-PAM, independent of species, in cell lines and native systems.
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Affiliation(s)
- Sean P. Moran
- Vanderbilt Brain Institute, Vanderbilt University, Nashville, Tennessee 37232, United States
- Department of Pharmacology, Vanderbilt University, Nashville, Tennessee 37232, United States
- Vanderbilt Center for Neuroscience Drug Discovery, Vanderbilt University, Nashville, Tennessee 37232, United States
| | - Hyekyung P. Cho
- Department of Pharmacology, Vanderbilt University, Nashville, Tennessee 37232, United States
- Vanderbilt Center for Neuroscience Drug Discovery, Vanderbilt University, Nashville, Tennessee 37232, United States
| | - James Maksymetz
- Department of Pharmacology, Vanderbilt University, Nashville, Tennessee 37232, United States
- Vanderbilt Center for Neuroscience Drug Discovery, Vanderbilt University, Nashville, Tennessee 37232, United States
| | - Daniel H. Remke
- Department of Pharmacology, Vanderbilt University, Nashville, Tennessee 37232, United States
- Vanderbilt Center for Neuroscience Drug Discovery, Vanderbilt University, Nashville, Tennessee 37232, United States
| | - Ryan M. Hanson
- Vanderbilt Center for Neuroscience Drug Discovery, Vanderbilt University, Nashville, Tennessee 37232, United States
| | - Colleen M. Niswender
- Department of Pharmacology, Vanderbilt University, Nashville, Tennessee 37232, United States
- Department of Chemistry, Vanderbilt University, Nashville, Tennessee 37232, United States
- Vanderbilt Kennedy Center, Vanderbilt University Medical Center, Nashville, Tennessee 37240, United States
| | - Craig W. Lindsley
- Department of Pharmacology, Vanderbilt University, Nashville, Tennessee 37232, United States
- Vanderbilt Center for Neuroscience Drug Discovery, Vanderbilt University, Nashville, Tennessee 37232, United States
- Department of Chemistry, Vanderbilt University, Nashville, Tennessee 37232, United States
| | - Jerri M. Rook
- Vanderbilt Brain Institute, Vanderbilt University, Nashville, Tennessee 37232, United States
- Department of Pharmacology, Vanderbilt University, Nashville, Tennessee 37232, United States
- Vanderbilt Center for Neuroscience Drug Discovery, Vanderbilt University, Nashville, Tennessee 37232, United States
| | - P. Jeffrey Conn
- Vanderbilt Brain Institute, Vanderbilt University, Nashville, Tennessee 37232, United States
- Department of Pharmacology, Vanderbilt University, Nashville, Tennessee 37232, United States
- Vanderbilt Center for Neuroscience Drug Discovery, Vanderbilt University, Nashville, Tennessee 37232, United States
- Vanderbilt Kennedy Center, Vanderbilt University Medical Center, Nashville, Tennessee 37240, United States
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10
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Berizzi AE, Bender AM, Lindsley CW, Conn PJ, Sexton PM, Langmead CJ, Christopoulos A. Structure-Activity Relationships of Pan-Gα q/11 Coupled Muscarinic Acetylcholine Receptor Positive Allosteric Modulators. ACS Chem Neurosci 2018; 9:1818-1828. [PMID: 29683647 DOI: 10.1021/acschemneuro.8b00136] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023] Open
Abstract
Recent years have seen a large increase in the discovery of allosteric ligands targeting muscarinic acetylcholine receptors (mAChRs). One of the challenges in screening such compounds is to understand their mechanisms of action and define appropriate parameter estimates for affinity, cooperativity and efficacy. Herein we describe the mechanisms of action and structure-activity relationships for a series of "pan-Gq-coupled" muscarinic acetylcholine (ACh) receptor (mAChR) positive allosteric modulators (PAMs). Using a combination of radioligand binding, functional inositol phosphate accumulation assays, receptor alkylation and operational data analysis, we show that most compounds in the series derive their variable potency and selectivity from differential cooperativity at the M1, M3 and M5 mAChRs. None of the PAMs showed greater than 10-fold subtype selectivity for the agonist-free receptor, but VU6007705, VU6007678, and VU6008555 displayed markedly increased cooperativity compared to the parent molecule and M5 mAChR-preferring PAM, ML380 (αβ > 100), in the presence of ACh. Most of the activity of these PAMs derives from their ability to potentiate ACh binding affinity at mAChRs, though VU6007678 was notable for also potentiating ACh signaling efficacy and robust allosteric agonist activity. These data provide key insights for the future design of more potent and subtype-selective mAChR PAMs.
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Affiliation(s)
- Alice E. Berizzi
- Drug Discovery Biology, Monash Institute of Pharmaceutical Sciences, Monash University, Parkville, Victoria 3052, Australia
| | - Aaron M. Bender
- Departments of Pharmacology & Chemistry, Vanderbilt Center for Neuroscience Drug Discovery, Vanderbilt University, Nashville, Tennessee 37232, United States
| | - Craig W. Lindsley
- Departments of Pharmacology & Chemistry, Vanderbilt Center for Neuroscience Drug Discovery, Vanderbilt University, Nashville, Tennessee 37232, United States
| | - P. Jeffrey Conn
- Departments of Pharmacology & Chemistry, Vanderbilt Center for Neuroscience Drug Discovery, Vanderbilt University, Nashville, Tennessee 37232, United States
| | - Patrick M. Sexton
- Drug Discovery Biology, Monash Institute of Pharmaceutical Sciences, Monash University, Parkville, Victoria 3052, Australia
| | - Christopher J. Langmead
- Drug Discovery Biology, Monash Institute of Pharmaceutical Sciences, Monash University, Parkville, Victoria 3052, Australia
| | - Arthur Christopoulos
- Drug Discovery Biology, Monash Institute of Pharmaceutical Sciences, Monash University, Parkville, Victoria 3052, Australia
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11
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Current status of muscarinic M1 and M4 receptors as drug targets for neurodegenerative diseases. Neuropharmacology 2018; 136:449-458. [PMID: 29374561 DOI: 10.1016/j.neuropharm.2018.01.028] [Citation(s) in RCA: 48] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2017] [Revised: 01/09/2018] [Accepted: 01/21/2018] [Indexed: 01/17/2023]
Abstract
The cholinergic signalling system has been an attractive pathway to seek targets for modulation of arousal, cognition, and attention which are compromised in neurodegenerative and neuropsychiatric diseases. The acetylcholine muscarinic receptor M1 and M4 subtypes which are highly expressed in the central nervous system, in cortex, hippocampus and striatum, key areas of cognitive and neuropsychiatric control, have received particular attention. Historical muscarinic drug development yielded first generation agonists with modest selectivity for these two receptor targets over M2 and M3 receptors, the major peripheral sub-types hypothesised to underlie the dose-limiting clinical side effects. More recent compound screening and medicinal chemistry optimization of orthosteric and allosteric agonists, and positive allosteric modulators binding to sites distinct from the highly homologous acetylcholine binding pocket have yielded a collection of highly selective tool compounds for preclinical validation studies. Several M1 selective ligands have progressed to early clinical development and in time will hopefully lead to useful therapeutics for treating symptoms of Alzheimer's disease and related disorders. This article is part of the Special Issue entitled 'Neuropharmacology on Muscarinic Receptors'.
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12
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Betterton RT, Broad LM, Tsaneva‐Atanasova K, Mellor JR. Acetylcholine modulates gamma frequency oscillations in the hippocampus by activation of muscarinic M1 receptors. Eur J Neurosci 2017; 45:1570-1585. [PMID: 28406538 PMCID: PMC5518221 DOI: 10.1111/ejn.13582] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/24/2016] [Revised: 04/04/2017] [Accepted: 04/07/2017] [Indexed: 12/21/2022]
Abstract
Modulation of gamma oscillations is important for the processing of information and the disruption of gamma oscillations is a prominent feature of schizophrenia and Alzheimer's disease. Gamma oscillations are generated by the interaction of excitatory and inhibitory neurons where their precise frequency and amplitude are controlled by the balance of excitation and inhibition. Acetylcholine enhances the intrinsic excitability of pyramidal neurons and suppresses both excitatory and inhibitory synaptic transmission, but the net modulatory effect on gamma oscillations is not known. Here, we find that the power, but not frequency, of optogenetically induced gamma oscillations in the CA3 region of mouse hippocampal slices is enhanced by low concentrations of the broad‐spectrum cholinergic agonist carbachol but reduced at higher concentrations. This bidirectional modulation of gamma oscillations is replicated within a mathematical model by neuronal depolarisation, but not by reducing synaptic conductances, mimicking the effects of muscarinic M1 receptor activation. The predicted role for M1 receptors was supported experimentally; bidirectional modulation of gamma oscillations by acetylcholine was replicated by a selective M1 receptor agonist and prevented by genetic deletion of M1 receptors. These results reveal that acetylcholine release in CA3 of the hippocampus modulates gamma oscillation power but not frequency in a bidirectional and dose‐dependent manner by acting primarily through muscarinic M1 receptors.
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Affiliation(s)
- Ruth T. Betterton
- Centre for Synaptic PlasticitySchool of Physiology, Pharmacology and NeuroscienceUniversity of BristolBristolBS8 1TDUK
| | | | - Krasimira Tsaneva‐Atanasova
- Department of MathematicsCollege of Engineering, Mathematics and Physical SciencesUniversity of ExeterExeterEX4 4QFUK
| | - Jack R. Mellor
- Centre for Synaptic PlasticitySchool of Physiology, Pharmacology and NeuroscienceUniversity of BristolBristolBS8 1TDUK
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13
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Udawela M, Scarr E, Boer S, Um JY, Hannan AJ, McOmish C, Felder CC, Thomas EA, Dean B. Isoform specific differences in phospholipase C beta 1 expression in the prefrontal cortex in schizophrenia and suicide. NPJ SCHIZOPHRENIA 2017; 3:19. [PMID: 28560265 PMCID: PMC5441535 DOI: 10.1038/s41537-017-0020-x] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 12/04/2016] [Revised: 03/09/2017] [Accepted: 03/21/2017] [Indexed: 11/09/2022]
Abstract
Our previous study demonstrated that phospholipase C beta 1 mRNA was down-regulated in Brodmann's area 46 from subjects with schizophrenia. However, phospholipase C beta 1 protein has also been shown to be lower in Brodmann's area 8 and 9 from teenage suicide subjects, creating a potential confound in interpreting the findings in schizophrenia due to the high suicide rate associated with this disorder. To begin to reconcile and consolidate these findings, in this study, we measured mRNA and protein levels of phospholipase C beta 1 variants a and b in Brodmann's area 46 and Brodmann's area 9 from subjects with schizophrenia, many of whom were suicide completers, and determined the diagnostic specificity of observed findings. Consistent with our previous study, levels of phospholipase C beta 1 a and b mRNA, but not protein, were lower in Brodmann's area 46 from subjects with schizophrenia. In Brodmann's area 9, phospholipase C beta 1a protein levels were lower in subjects with schizophrenia, while phospholipase C beta 1b mRNA was higher and protein was lower in those that had died of suicide. Altered protein levels in Brodmann's area 9 appeared to be diagnostically specific, as we did not detect these changes in subjects with bipolar disorder, major depressive disorder or suicide completers with no diagnosis of mental illness. We further assessed the relationship between phospholipase C beta 1 and levels of muscarinic receptors (CHRMs) that signal through this protein, in both human and Chrm knockout mouse central nervous system tissue, and found no strong relationship between the two. Understanding central nervous system differences in downstream effector pathways in schizophrenia may lead to improved treatment strategies and help to identify those at risk of suicide.
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Affiliation(s)
- M Udawela
- Molecular Psychiatry Laboratories, Florey Institute of Neuroscience and Mental Health, University of Melbourne, Parkville, VIC Australia
| | - E Scarr
- Molecular Psychiatry Laboratories, Florey Institute of Neuroscience and Mental Health, University of Melbourne, Parkville, VIC Australia
- Department of Psychiatry, University of Melbourne, Parkville, VIC Australia
| | - S Boer
- Molecular Psychiatry Laboratories, Florey Institute of Neuroscience and Mental Health, University of Melbourne, Parkville, VIC Australia
| | - J Y Um
- Molecular Psychiatry Laboratories, Florey Institute of Neuroscience and Mental Health, University of Melbourne, Parkville, VIC Australia
- Cardiovascular and Neurology Products Division, Drug Evaluation Department, National Institute of Food and Drug Safety Evaluation, Osong Health Technology Administration Complex, Chungcheongbuk-do, South Korea
| | - A J Hannan
- Epigenetics and Neural Plasticity Laboratory, Florey Institute of Neuroscience and Mental Health, University of Melbourne, Parkville, VIC Australia
| | - C McOmish
- Molecular Psychiatry Laboratories, Florey Institute of Neuroscience and Mental Health, University of Melbourne, Parkville, VIC Australia
| | - C C Felder
- Lilly Research Laboratories, Neuroscience Research Division, Eli Lilly and Company, Lilly Corporate Center, Indianapolis, IN USA
| | - E A Thomas
- Department of Molecular and Cellular Neuroscience, The Scripps Research Institute, La Jolla, CA USA
| | - B Dean
- Molecular Psychiatry Laboratories, Florey Institute of Neuroscience and Mental Health, University of Melbourne, Parkville, VIC Australia
- Cardiovascular and Neurology Products Division, Drug Evaluation Department, National Institute of Food and Drug Safety Evaluation, Osong Health Technology Administration Complex, Chungcheongbuk-do, South Korea
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14
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Felder CC, Schober DA, Tu Y, Quets A, Xiao H, Watt M, Siuda E, Nisenbaum E, Xiang C, Heinz B, Prieto L, McKinzie DL, Monn JA. Translational Pharmacology of the Metabotropic Glutamate 2 Receptor–Preferring Agonist LY2812223 in the Animal and Human Brain. J Pharmacol Exp Ther 2017; 361:190-197. [DOI: 10.1124/jpet.116.237859] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2016] [Accepted: 01/12/2017] [Indexed: 11/22/2022] Open
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15
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Ferreira-Vieira TH, Guimaraes IM, Silva FR, Ribeiro FM. Alzheimer's disease: Targeting the Cholinergic System. Curr Neuropharmacol 2016; 14:101-15. [PMID: 26813123 PMCID: PMC4787279 DOI: 10.2174/1570159x13666150716165726] [Citation(s) in RCA: 837] [Impact Index Per Article: 104.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2014] [Revised: 07/01/2015] [Accepted: 07/14/2015] [Indexed: 12/16/2022] Open
Abstract
Acetylcholine (ACh) has a crucial role in the peripheral and central nervous
systems. The enzyme choline acetyltransferase (ChAT) is responsible for
synthesizing ACh from acetyl-CoA and choline in the cytoplasm and the vesicular
acetylcholine transporter (VAChT) uptakes the neurotransmitter into synaptic
vesicles. Following depolarization, ACh undergoes exocytosis reaching the
synaptic cleft, where it can bind its receptors, including muscarinic and
nicotinic receptors. ACh present at the synaptic cleft is promptly hydrolyzed by
the enzyme acetylcholinesterase (AChE), forming acetate and choline, which is
recycled into the presynaptic nerve terminal by the high-affinity choline
transporter (CHT1). Cholinergic neurons located in the basal forebrain,
including the neurons that form the nucleus basalis of Meynert, are severely
lost in Alzheimer’s disease (AD). AD is the most ordinary cause of dementia
affecting 25 million people worldwide. The hallmarks of the disease are the
accumulation of neurofibrillary tangles and amyloid plaques. However, there is
no real correlation between levels of cortical plaques and AD-related cognitive
impairment. Nevertheless, synaptic loss is the principal correlate of disease
progression and loss of cholinergic neurons contributes to memory and attention
deficits. Thus, drugs that act on the cholinergic system represent a promising
option to treat AD patients.
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Affiliation(s)
| | | | | | - Fabiola M Ribeiro
- Departamento de Bioquimica e Imunologia, Instituto de Ciencias Biologicas, Universidade Federal de Minas Gerais, Belo Horizonte, Brazil.
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16
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Choy KHC, Shackleford DM, Malone DT, Mistry SN, Patil RT, Scammells PJ, Langmead CJ, Pantelis C, Sexton PM, Lane JR, Christopoulos A. Positive Allosteric Modulation of the Muscarinic M1 Receptor Improves Efficacy of Antipsychotics in Mouse Glutamatergic Deficit Models of Behavior. J Pharmacol Exp Ther 2016; 359:354-365. [PMID: 27630144 DOI: 10.1124/jpet.116.235788] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2016] [Accepted: 09/13/2016] [Indexed: 12/14/2022] Open
Abstract
Current antipsychotics are effective in treating the positive symptoms associated with schizophrenia, but they remain suboptimal in targeting cognitive dysfunction. Recent studies have suggested that positive allosteric modulation of the M1 muscarinic acetylcholine receptor (mAChR) may provide a novel means of improving cognition. However, very little is known about the potential of combination therapies in extending coverage across schizophrenic symptom domains. This study investigated the effect of the M1 mAChR positive allosteric modulator BQCA [1-(4-methoxybenzyl)-4-oxo-1,4-dihydroquinoline-3-carboxylic acid], alone or in combination with haloperidol (a first-generation antipsychotic), clozapine (a second-generation atypical antipsychotic), or aripiprazole (a third-generation atypical antipsychotic), in reversing deficits in sensorimotor gating and spatial memory induced by the N-methyl-d-aspartate receptor antagonist, MK-801 [(5R,10S)-(+)-5-methyl-10,11-dihydro-5H-dibenzo[a,d]cyclohepten-5,10-imine]. Sensorimotor gating and spatial memory induction are two models that represent aspects of schizophrenia modeled in rodents. In prepulse inhibition (an operational measure of sensorimotor gating), BQCA alone had minimal effects but exhibited different levels of efficacy in reversing MK-801-induced prepulse inhibition disruptions when combined with a subeffective dose of each of the three (currently prescribed) antipsychotics. Furthermore, the combined effect of BQCA and clozapine was absent in M1-/- mice. Interestingly, although BQCA alone had no effect in reversing MK-801-induced memory impairments in a Y-maze spatial test, we observed a reversal upon the combination of BQCA with atypical antipsychotics, but not with haloperidol. These findings provide proof of concept that a judicious combination of existing antipsychotics with a selective M1 mAChR positive allosteric modulator can extend antipsychotic efficacy in glutamatergic deficit models of behavior.
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Affiliation(s)
- Kwok H C Choy
- Drug Discovery Biology (K.H.C.C., D.T.M, C.J.L, P.M.S, J.R.L, A.C.), Centre for Drug Candidate Optimization (D.M.S., R.T.P.), and Medicinal Chemistry (S.N.M, P.J.S.), Monash Institute of Pharmaceutical Sciences, Monash University, Parkville, Australia; and Melbourne Neuropsychiatry Centre, Department of Psychiatry and Centre for Neural Engineering, University of Melbourne, Melbourne, Australia (C.P.)
| | - David M Shackleford
- Drug Discovery Biology (K.H.C.C., D.T.M, C.J.L, P.M.S, J.R.L, A.C.), Centre for Drug Candidate Optimization (D.M.S., R.T.P.), and Medicinal Chemistry (S.N.M, P.J.S.), Monash Institute of Pharmaceutical Sciences, Monash University, Parkville, Australia; and Melbourne Neuropsychiatry Centre, Department of Psychiatry and Centre for Neural Engineering, University of Melbourne, Melbourne, Australia (C.P.)
| | - Daniel T Malone
- Drug Discovery Biology (K.H.C.C., D.T.M, C.J.L, P.M.S, J.R.L, A.C.), Centre for Drug Candidate Optimization (D.M.S., R.T.P.), and Medicinal Chemistry (S.N.M, P.J.S.), Monash Institute of Pharmaceutical Sciences, Monash University, Parkville, Australia; and Melbourne Neuropsychiatry Centre, Department of Psychiatry and Centre for Neural Engineering, University of Melbourne, Melbourne, Australia (C.P.)
| | - Shailesh N Mistry
- Drug Discovery Biology (K.H.C.C., D.T.M, C.J.L, P.M.S, J.R.L, A.C.), Centre for Drug Candidate Optimization (D.M.S., R.T.P.), and Medicinal Chemistry (S.N.M, P.J.S.), Monash Institute of Pharmaceutical Sciences, Monash University, Parkville, Australia; and Melbourne Neuropsychiatry Centre, Department of Psychiatry and Centre for Neural Engineering, University of Melbourne, Melbourne, Australia (C.P.)
| | - Rahul T Patil
- Drug Discovery Biology (K.H.C.C., D.T.M, C.J.L, P.M.S, J.R.L, A.C.), Centre for Drug Candidate Optimization (D.M.S., R.T.P.), and Medicinal Chemistry (S.N.M, P.J.S.), Monash Institute of Pharmaceutical Sciences, Monash University, Parkville, Australia; and Melbourne Neuropsychiatry Centre, Department of Psychiatry and Centre for Neural Engineering, University of Melbourne, Melbourne, Australia (C.P.)
| | - Peter J Scammells
- Drug Discovery Biology (K.H.C.C., D.T.M, C.J.L, P.M.S, J.R.L, A.C.), Centre for Drug Candidate Optimization (D.M.S., R.T.P.), and Medicinal Chemistry (S.N.M, P.J.S.), Monash Institute of Pharmaceutical Sciences, Monash University, Parkville, Australia; and Melbourne Neuropsychiatry Centre, Department of Psychiatry and Centre for Neural Engineering, University of Melbourne, Melbourne, Australia (C.P.)
| | - Christopher J Langmead
- Drug Discovery Biology (K.H.C.C., D.T.M, C.J.L, P.M.S, J.R.L, A.C.), Centre for Drug Candidate Optimization (D.M.S., R.T.P.), and Medicinal Chemistry (S.N.M, P.J.S.), Monash Institute of Pharmaceutical Sciences, Monash University, Parkville, Australia; and Melbourne Neuropsychiatry Centre, Department of Psychiatry and Centre for Neural Engineering, University of Melbourne, Melbourne, Australia (C.P.)
| | - Christos Pantelis
- Drug Discovery Biology (K.H.C.C., D.T.M, C.J.L, P.M.S, J.R.L, A.C.), Centre for Drug Candidate Optimization (D.M.S., R.T.P.), and Medicinal Chemistry (S.N.M, P.J.S.), Monash Institute of Pharmaceutical Sciences, Monash University, Parkville, Australia; and Melbourne Neuropsychiatry Centre, Department of Psychiatry and Centre for Neural Engineering, University of Melbourne, Melbourne, Australia (C.P.)
| | - Patrick M Sexton
- Drug Discovery Biology (K.H.C.C., D.T.M, C.J.L, P.M.S, J.R.L, A.C.), Centre for Drug Candidate Optimization (D.M.S., R.T.P.), and Medicinal Chemistry (S.N.M, P.J.S.), Monash Institute of Pharmaceutical Sciences, Monash University, Parkville, Australia; and Melbourne Neuropsychiatry Centre, Department of Psychiatry and Centre for Neural Engineering, University of Melbourne, Melbourne, Australia (C.P.)
| | - Johnathan R Lane
- Drug Discovery Biology (K.H.C.C., D.T.M, C.J.L, P.M.S, J.R.L, A.C.), Centre for Drug Candidate Optimization (D.M.S., R.T.P.), and Medicinal Chemistry (S.N.M, P.J.S.), Monash Institute of Pharmaceutical Sciences, Monash University, Parkville, Australia; and Melbourne Neuropsychiatry Centre, Department of Psychiatry and Centre for Neural Engineering, University of Melbourne, Melbourne, Australia (C.P.)
| | - Arthur Christopoulos
- Drug Discovery Biology (K.H.C.C., D.T.M, C.J.L, P.M.S, J.R.L, A.C.), Centre for Drug Candidate Optimization (D.M.S., R.T.P.), and Medicinal Chemistry (S.N.M, P.J.S.), Monash Institute of Pharmaceutical Sciences, Monash University, Parkville, Australia; and Melbourne Neuropsychiatry Centre, Department of Psychiatry and Centre for Neural Engineering, University of Melbourne, Melbourne, Australia (C.P.)
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17
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Jeon WJ, Dean B, Scarr E, Gibbons A. The Role of Muscarinic Receptors in the Pathophysiology of Mood Disorders: A Potential Novel Treatment? Curr Neuropharmacol 2016; 13:739-49. [PMID: 26630954 PMCID: PMC4759313 DOI: 10.2174/1570159x13666150612230045] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2014] [Revised: 12/30/2014] [Accepted: 02/28/2015] [Indexed: 12/21/2022] Open
Abstract
The central cholinergic system has been implicated in the pathophysiology of mood disorders. An imbalance in central cholinergic neurotransmitter activity has been proposed to contribute to the manic and depressive episodes typical of these disorders. Neuropharmacological studies into the effects of cholinergic agonists and antagonists on mood state have provided considerable support for this hypothesis. Furthermore, recent clinical studies have shown that the pan-CHRM antagonist, scopolamine, produces rapid-acting antidepressant effects in individuals with either major depressive disorder (MDD) or bipolar disorder (BPD), such as bipolar depression, contrasting the delayed therapeutic response of conventional mood stabilisers and antidepressants. This review presents recent data from neuroimaging, post-mortem and genetic studies supporting the involvement of muscarinic cholinergic receptors (CHRMs), particularly CHRM2, in the pathophysiology of MDD and BPD. Thus, novel drugs that selectively target CHRMs with negligible effects in the peripheral nervous system might produce more rapid and robust clinical improvement in patients with BPD and MDD.
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Affiliation(s)
| | - Brian Dean
- Florey Institute for Neuroscience and Mental Health, 30 Royal Parade, Parkville, Victoria 3052, Australia.
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18
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Berizzi AE, Gentry PR, Rueda P, Den Hoedt S, Sexton PM, Langmead CJ, Christopoulos A. Molecular Mechanisms of Action of M5 Muscarinic Acetylcholine Receptor Allosteric Modulators. Mol Pharmacol 2016; 90:427-36. [DOI: 10.1124/mol.116.104182] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2016] [Accepted: 07/18/2016] [Indexed: 11/22/2022] Open
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19
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Smith DL, Davoren JE, Edgerton JR, Lazzaro JT, Lee CW, Neal S, Zhang L, Grimwood S. Characterization of a Novel M1 Muscarinic Acetylcholine Receptor Positive Allosteric Modulator Radioligand, [3H]PT-1284. Mol Pharmacol 2016; 90:177-87. [DOI: 10.1124/mol.116.104737] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2016] [Accepted: 06/30/2016] [Indexed: 12/18/2022] Open
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20
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Dean B, Hopper S, Conn PJ, Scarr E. Changes in BQCA Allosteric Modulation of [(3)H]NMS Binding to Human Cortex within Schizophrenia and by Divalent Cations. Neuropsychopharmacology 2016; 41:1620-8. [PMID: 26511338 PMCID: PMC4832025 DOI: 10.1038/npp.2015.330] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/23/2015] [Revised: 10/04/2015] [Accepted: 10/20/2015] [Indexed: 02/06/2023]
Abstract
Stimulation of the cortical muscarinic M1 receptor (CHRM1) is proposed as a treatment for schizophrenia, a hypothesis testable using CHRM1 allosteric modulators. Allosteric modulators have been shown to change the activity of CHRMs using cloned human CHRMs and CHRM knockout mice but not human CNS, a prerequisite for them working in humans. Here we show in vitro that BQCA, a positive allosteric CHRM1 modulator, brings about the expected change in affinity of the CHRM1 orthosteric site for acetylcholine in human cortex. Moreover, this effect of BQCA is reduced in the cortex of a subset of subjects with schizophrenia, separated into a discrete population because of a profound loss of cortical [(3)H]pirenzepine binding. Surprisingly, there was no change in [(3)H]NMS binding to the cortex from this subset or those with schizophrenia but without a marked loss of cortical CHRM1. Hence, we explored the nature of [(3)H]pirenzepine and [(3)H]NMS binding to human cortex and showed total [(3)H]pirenzepine and [(3)H]NMS binding was reduced by Zn(2+), acetylcholine displacement of [(3)H]NMS binding was enhanced by Mg(2+) and Zn(2+), acetylcholine displacement of [(3)H]pirenzepine was reduced by Mg(2+) and enhanced by Zn(2+), whereas BQCA effects on [(3)H]NMS, but not [(3)H]pirenzepine, binding was enhanced by Mg(2+) and Zn(2+). These data suggest the orthosteric and allosteric sites on CHRMs respond differently to divalent cations and the effects of allosteric modulation of the cortical CHRM1 is reduced in a subset of people with schizophrenia, a finding that may have ramifications for the use of CHRM1 allosteric modulators in the treatment of schizophrenia.
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Affiliation(s)
- Brian Dean
- The Florey Institute for Neuroscience and Mental Health, Parkville, VIC, Australia,The CRC for Mental Health, Parkville, VIC, Australia,Department of Psychiatry, The University of Melbourne, Parkville, VIC, Australia,The Molecular Psychiatry Laboratory, The Florey Institute for Neuroscience and Mental Health, 30 Royal Parade, Parkville, VIC 3052, Australia, Tel: +61 3 8344 3786, Fax: +61 3 9348 1707, E-mail:
| | - Shaun Hopper
- The Florey Institute for Neuroscience and Mental Health, Parkville, VIC, Australia,The CRC for Mental Health, Parkville, VIC, Australia,Department of Psychiatry, The University of Melbourne, Parkville, VIC, Australia
| | - P Jeffrey Conn
- Vanderbilt Center for Neuroscience Drug Discovery, Department of Pharmacology, Vanderbilt University School of Medicine, Nashville, TN, USA
| | - Elizabeth Scarr
- The Florey Institute for Neuroscience and Mental Health, Parkville, VIC, Australia,The CRC for Mental Health, Parkville, VIC, Australia,Department of Psychiatry, The University of Melbourne, Parkville, VIC, Australia
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21
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Butcher AJ, Bradley SJ, Prihandoko R, Brooke SM, Mogg A, Bourgognon JM, Macedo-Hatch T, Edwards JM, Bottrill AR, Challiss RAJ, Broad LM, Felder CC, Tobin AB. An Antibody Biosensor Establishes the Activation of the M1 Muscarinic Acetylcholine Receptor during Learning and Memory. J Biol Chem 2016; 291:8862-75. [PMID: 26826123 PMCID: PMC4861454 DOI: 10.1074/jbc.m115.681726] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2015] [Indexed: 11/15/2022] Open
Abstract
Establishing the in vivo activation status of G protein-coupled receptors would not only indicate physiological roles of G protein-coupled receptors but would also aid drug discovery by establishing drug/receptor engagement. Here, we develop a phospho-specific antibody-based biosensor to detect activation of the M1 muscarinic acetylcholine receptor (M1 mAChR) in vitro and in vivo. Mass spectrometry phosphoproteomics identified 14 sites of phosphorylation on the M1 mAChR. Phospho-specific antibodies to four of these sites established that serine at position 228 (Ser228) on the M1 mAChR showed extremely low levels of basal phosphorylation that were significantly up-regulated by orthosteric agonist stimulation. In addition, the M1 mAChR-positive allosteric modulator, 1-(4-methoxybenzyl)-4-oxo-1,4-dihydroquinoline-3-carboxylic acid, enhanced acetylcholine-mediated phosphorylation at Ser228. These data supported the hypothesis that phosphorylation at Ser228 was an indicator of M1 mAChR activation. This was further supported in vivo by the identification of phosphorylated Ser228 on the M1 mAChR in the hippocampus of mice following administration of the muscarinic ligands xanomeline and 1-(4-methoxybenzyl)-4-oxo-1,4-dihydroquinoline-3-carboxylic acid. Finally, Ser228 phosphorylation was seen to increase in the CA1 region of the hippocampus following memory acquisition, a response that correlated closely with up-regulation of CA1 neuronal activity. Thus, determining the phosphorylation status of the M1 mAChR at Ser228 not only provides a means of establishing receptor activation following drug treatment both in vitro and in vivo but also allows for the mapping of the activation status of the M1 mAChR in the hippocampus following memory acquisition thereby establishing a link between M1 mAChR activation and hippocampus-based memory and learning.
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Affiliation(s)
| | | | | | | | - Adrian Mogg
- Eli Lilly and Co. Neuroscience, Erl Wood Manor, Windlesham, Surrey GU20 6PH, United Kingdom
| | | | | | | | - Andrew R Bottrill
- Protein and Nucleic Acid Chemistry Laboratory, University of Leicester, Hodgkin Building, Lancaster Road, Leicester LE1 9HN, United Kingdom
| | - R A John Challiss
- the Department of Molecular and Cell Biology, University of Leicester, Henry Wellcome Building, Lancaster Road, Leicester LE1 9HN, United Kingdom
| | - Lisa M Broad
- Eli Lilly and Co. Neuroscience, Erl Wood Manor, Windlesham, Surrey GU20 6PH, United Kingdom
| | - Christian C Felder
- Eli Lilly and Co. Neuroscience, Lilly Corporate Center, Indianapolis, Indiana 46285, and
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Wang J, Liu J, Chen S, Gao Y, Meng F, Qiao L. Acupuncture effects on the hippocampal cholinergic system in a rat model of neuropathic pain. Neural Regen Res 2015; 7:212-8. [PMID: 25767502 PMCID: PMC4353117 DOI: 10.3969/j.issn.1673-5374.2012.03.010] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2011] [Accepted: 12/25/2011] [Indexed: 11/18/2022] Open
Abstract
The present study observed the effects of repeated electroacupuncture of Zusanli (ST36) and Yanglingquan (GB34) on expression of hippocampal acetylcholinesterase, vesicular acetylcholine transporter, and muscarinic M1 receptor mRNA in chronic constrictive injury (neuropathic pain) and/or ovariotomy rats. Results demonstrated increased expression of hippocampal acetylcholinesterase, vesicular acetylcholine transporter, and muscarinic M1 receptor mRNA, as well as decreased pain threshold, in a rat model of chronic neuropathic pain after electroacupuncture. The effects of electroacupuncture increased with prolonged time, but the above-mentioned effects decreased in memory-deficient animals. Results indicated that repeated electroacupuncture has a cumulative analgesic effect, which is closely associated with upregulation of acetylcholinesterase and vesicular acetylcholine transporter activity, as well as M1 receptor mRNA expression and memory.
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Affiliation(s)
- Junying Wang
- Institute of Acu-moxibustion, China Academy of Chinese Medical Sciences, Beijing 100700, China
| | - Junling Liu
- Institute of Acu-moxibustion, China Academy of Chinese Medical Sciences, Beijing 100700, China
| | - Shuping Chen
- Institute of Acu-moxibustion, China Academy of Chinese Medical Sciences, Beijing 100700, China
| | - Yonghui Gao
- Institute of Acu-moxibustion, China Academy of Chinese Medical Sciences, Beijing 100700, China
| | - Fanying Meng
- Institute of Acu-moxibustion, China Academy of Chinese Medical Sciences, Beijing 100700, China
| | - Lina Qiao
- Institute of Acu-moxibustion, China Academy of Chinese Medical Sciences, Beijing 100700, China
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Nicotinic and muscarinic agonists and acetylcholinesterase inhibitors stimulate a common pathway to enhance GluN2B-NMDAR responses. Proc Natl Acad Sci U S A 2014; 111:12538-43. [PMID: 25114227 DOI: 10.1073/pnas.1408805111] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023] Open
Abstract
Nicotinic and muscarinic ACh receptor agonists and acetylcholinesterase inhibitors (AChEIs) can enhance cognitive function. However, it is unknown whether a common signaling pathway is involved in the effect. Here, we show that in vivo administration of nicotine, AChEIs, and an m1 muscarinic (m1) agonist increase glutamate receptor, ionotropic, N-methyl D-aspartate 2B (GluN2B)-containing NMDA receptor (NR2B-NMDAR) responses, a necessary component in memory formation, in hippocampal CA1 pyramidal cells, and that coadministration of the m1 antagonist pirenzepine prevents the effect of cholinergic drugs. These observations suggest that the effect of nicotine is secondary to increased release of ACh via the activation of nicotinic ACh receptors (nAChRs) and involves m1 receptor activation through ACh. In vitro activation of m1 receptors causes the selective enhancement of NR2B-NMDAR responses in CA1 pyramidal cells, and in vivo exposure to cholinergic drugs occludes the in vitro effect. Furthermore, in vivo exposure to cholinergic drugs suppresses the potentiating effect of Src on NMDAR responses in vitro. These results suggest that exposure to cholinergic drugs maximally stimulates the m1/guanine nucleotide-binding protein subunit alpha q/PKC/proline-rich tyrosine kinase 2/Src signaling pathway for the potentiation of NMDAR responses in vivo, occluding the in vitro effects of m1 activation and Src. Thus, our results indicate not only that nAChRs, ACh, and m1 receptors are on the same pathway involving Src signaling but also that NR2B-NMDARs are a point of convergence of cholinergic and glutamatergic pathways involved in learning and memory.
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A muscarinic view on Gq. Naunyn Schmiedebergs Arch Pharmacol 2013; 386:935-6. [DOI: 10.1007/s00210-013-0895-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
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25
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Widespread decreases in cortical muscarinic receptors in a subset of people with schizophrenia. Int J Neuropsychopharmacol 2013; 16:37-46. [PMID: 22338582 DOI: 10.1017/s1461145712000028] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/12/2023] Open
Abstract
These studies were undertaken to investigate the selectivity of cortical muscarinic receptor radioligand binding in muscarinic M(1) and M(4) receptor knockout mice and to determine whether a marked decrease in [(3)H]pirenzepine binding in Brodmann's area (BA) 9 from a subset of people with schizophrenia was predictive of decreased muscarinic receptors in other central nervous system (CNS) regions. Our data show that, under the conditions used, [(3)H]pirenzepine binding was highly selective for the muscarinic M(1) receptor whereas both [(3)H]AF-DX 386 and [(3)H]4DAMP had less discriminatory power. In addition, the data suggest that a marked decrease in [(3)H]pirenzepine binding in BA 9 from a subset of people with schizophrenia is predictive of decreases in muscarinic receptors in other CNS regions. However, there were some region-specific decreases in muscarinic receptors in tissue from people with schizophrenia who were outside this subset. These data add to a growing body of evidence suggesting there are widespread decreases in muscarinic receptors in the CNS of some subjects with schizophrenia, as demonstrated by neuroimaging. Our data have implications for understanding the potential clinical utility of drugs directed at the orthosteric and allosteric sites of muscarinic receptors to treat schizophrenia.
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McQuail JA, Davis KN, Miller F, Hampson RE, Deadwyler SA, Howlett AC, Nicolle MM. Hippocampal Gαq/₁₁ but not Gαo-coupled receptors are altered in aging. Neuropharmacology 2013; 70:63-73. [PMID: 23347951 DOI: 10.1016/j.neuropharm.2013.01.009] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2012] [Revised: 01/08/2013] [Accepted: 01/10/2013] [Indexed: 10/27/2022]
Abstract
Normal aging may limit the signaling efficacy of certain GPCRs by disturbing the function of specific Gα-subunits and leading to deficient modulation of intracellular functions that subserve synaptic plasticity, learning and memory. Evidence suggests that Gαq/₁₁ is more sensitive to the effects of aging relative to other Gα-subunits, including Gαo. To test this hypothesis, the functionality of Gαq/₁₁ and Gαo were compared in the hippocampus of young (6 months) and aged (24 months) F344 × BNF₁ hybrid rats assessed for spatial learning ability. Basal GTPγS-binding to Gαq/₁₁ was significantly elevated in aged rats relative to young and but not reliably associated with spatial learning. mAChR stimulation of Gαq/₁₁ with oxotremorine-M produced equivocal GTPγS-binding between age groups although values tended to be lower in the aged hippocampus and were inversely related to basal activity. Downstream Gαq/₁₁ function was measured in hippocampal subregion CA₁ by determining changes in [Ca(2+)]i after mAChR and mGluR (DHPG) stimulation. mAChR-stimulated peak change in [Ca(2+)]i was lower in aged CA₁ relative to young while mGluR-mediated integrated [Ca(2+)]i responses tended to be larger in aged. GPCR modulation of [Ca(2+)]i was observed to depend on intracellular stores to a greater degree in aged than young. In contrast, measures of Gαo-mediated GTPγS-binding were stable across age, including basal, mAChR-, GABABR (baclofen)-stimulated levels. Overall, the data indicate that aging selectively modulates the activity of Gαq/₁₁ within the hippocampus leading to deficient modulation of [Ca(2+)]i following stimulation of mAChRs but these changes are not related to spatial learning.
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Affiliation(s)
- Joseph A McQuail
- Neuroscience Program, Wake Forest University Graduate School of Arts & Sciences, Medical Center Boulevard, Winston-Salem, NC 27157, USA.
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Wang J, Ren Y, Zhu Y, Chen JW, Zhu MM, Xu YJ, Tan ZM. Effect of penehyclidine hydrochloride on the incidence of intra-operative awareness in Chinese patients undergoing breast cancer surgery during general anaesthesia. Anaesthesia 2012; 68:136-41. [DOI: 10.1111/anae.12092] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 10/14/2012] [Indexed: 11/30/2022]
Affiliation(s)
- J. Wang
- Department of Anaesthesiology; Fudan University; Shanghai Cancer Centre; Shanghai; China
| | - Y. Ren
- Department of Anaesthesiology; Fudan University; Shanghai Cancer Centre; Shanghai; China
| | - Y. Zhu
- Department of Anaesthesiology; Fudan University; Shanghai Cancer Centre; Shanghai; China
| | - J. W. Chen
- Department of Anaesthesiology; Fudan University; Shanghai Cancer Centre; Shanghai; China
| | - M. M. Zhu
- Department of Anaesthesiology; Fudan University; Shanghai Cancer Centre; Shanghai; China
| | - Y. J. Xu
- Department of Anaesthesiology; Fudan University; Shanghai Cancer Centre; Shanghai; China
| | - Z. M. Tan
- Department of Anaesthesiology; Fudan University; Shanghai Cancer Centre; Shanghai; China
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Harder D, Fotiadis D. Measuring substrate binding and affinity of purified membrane transport proteins using the scintillation proximity assay. Nat Protoc 2012; 7:1569-78. [PMID: 22864198 DOI: 10.1038/nprot.2012.090] [Citation(s) in RCA: 45] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
The scintillation proximity assay (SPA) is a rapid radioligand binding assay. Upon binding of radioactively labeled ligands (here L-[(3)H]arginine or D-[(3)H]glucose) to acceptor proteins immobilized on fluoromicrospheres (containing the scintillant), a light signal is stimulated and measured. The application of SPA to purified, detergent-solubilized membrane transport proteins allows substrate-binding properties to be assessed (e.g., substrate specificity and affinity), usually within 1 d. Notably, the SPA makes it possible to study specific transporters without interference from other cellular components, such as endogenous transporters. Reconstitution of the target transporter into proteoliposomes is not required. The SPA procedure allows high sample throughput and simple sample handling without the need for washing or separation steps: components are mixed in one well and the signal is measured directly after incubation. Therefore, the SPA is an excellent tool for high-throughput screening experiments, e.g., to search for substrates and inhibitors, and it has also recently become an attractive tool for drug discovery.
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Affiliation(s)
- Daniel Harder
- Institute of Biochemistry and Molecular Medicine, and Swiss National Centre of Competence in Research (NCCR) TransCure, University of Bern, Bern, Switzerland
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Raddatz R, Alper RH. Agonist-stimulated [35S]GTPγS binding. ACTA ACUST UNITED AC 2012; Chapter 2:Unit2.6. [PMID: 21948168 DOI: 10.1002/0471141755.ph0206s36] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
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Dontigny E, Patenaude C, Cyr M, Massicotte G. Sphingomyelinase selectively reduces M1 muscarinic receptors in rat hippocampal membranes. Hippocampus 2012; 22:1589-96. [PMID: 22228652 DOI: 10.1002/hipo.21001] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 11/09/2011] [Indexed: 01/20/2023]
Abstract
Although there is evidence that nicotinic acetylcholine (Ach) receptors are influenced by ceramides, we do not currently know whether or not these sphingolipids can also regulate the muscarinic subtypes of Ach receptors. Using the whole-cell patch technique, we demonstrated that the effectiveness of the muscarinic receptor agonist pilocarpine, in enhancing spontaneous inhibitory postsynaptic currents in CA1 pyramidal cells, was completely abolished in hippocampal slices pre-exposed to the ceramide-generating enzyme sphingomyelinase (SMase). Western blot experiments, performed with biotinylated hippocampal membranes, showed that this electrophysiological defect possibly relies on the loss of M1 muscarinic Ach receptors at the cell surface. However, the effect appears to be relatively specific as the cell-surface expression of M4 muscarinic receptors was not found to be impacted by SMase treatment. Interestingly, we observed that G protein-coupled receptor kinases 2 and β-arrestin1/2 interactions with M1-immunoprecipitated proteins were substantially augmented in SMase-treated slices and that the reduction of cell-surface M1 muscarinic receptor expression generated was completely suppressed by the muscarinic antagonist atropine. Collectively, our data suggest that selective internalization of M1 muscarinic receptors can be accentuated in neurons subjected to high ceramide levels. The potential physiopathological implications of this finding are presented.
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Affiliation(s)
- Eve Dontigny
- Groupe de recherche en Neuroscience, Université du Québec à Trois-Rivières, Trois-Rivières, Québec, Canada
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Muscarinic acetylcholine receptor-mediated activation of G(q) in rat brain membranes determined by guanosine-5'-O-(3-[35S]thio)triphosphate ([35S]GTPγS) binding using an anti-G protein scintillation proximity assay. J Neural Transm (Vienna) 2011; 119:525-32. [PMID: 22127550 DOI: 10.1007/s00702-011-0742-2] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/07/2011] [Accepted: 11/20/2011] [Indexed: 10/15/2022]
Abstract
In the present study, we performed antibody-capture guanosine-5'-O-(3-[(35)S]thio)triphosphate ([(35)S]GTPγS) scintillation proximity assay (SPA), in which immuno-capture of Gα subunits following [(35)S]GTPγS binding was combined with SPA technology, in rat brain membranes. Preliminary experiments using a series of agonists and commercially available anti-Gα antibodies indicated the increase in specific [(35)S]GTPγS binding to Gα(q) determined with the anti-Gα antibody sc-393 and evoked by carbamylcholine chloride (CCh) was pharmacologically relevant. The experimental conditions were optimized as for the concentrations of GDP, MgCl(2), and NaCl, the dilution of the anti-Gα(q) antibody, and membrane protein contents incubated. Under the optimized conditions, CCh-stimulated specific [(35)S]GTPγS binding to Gα(q) in a concentration-dependent and saturable manner with an EC(50) of around 10 μM in all of the membranes prepared from rat hippocampus, cerebral cortex, and striatum. The maximum responses were varied according to the brain regions, with the rank order in magnitude of hippocampus > cerebral cortex > striatum. The addition of MT-7, a snake toxin with high selectivity for M(1) over the other muscarinic acetylcholine receptors (mAChRs) (M(2)-M(5)), almost completely extinguished CCh-stimulated [(35)S]GTPγS binding to Gα(q), even at a concentration as low as 1 nM. These results indicate that the functional coupling between M(1) mAChR and Gα(q) can be investigated in rat native brain membranes by means of antibody-capture SPA/[(35)S]GTPγS binding assay. The assay developed in the present study would provide a useful strategy for investigation of possible pathophysiological alterations in neuropsychiatric disorders such as Alzheimer's disease and schizophrenia as well as for drug discovery.
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da Silva DC, de Medeiros WAA, Batista IDFC, Pimenta DC, Lebrun I, Abdalla FMF, Sandoval MRL. Characterization of a new muscarinic toxin from the venom of the Brazilian coral snake Micrurus lemniscatus in rat hippocampus. Life Sci 2011; 89:931-8. [PMID: 22005021 DOI: 10.1016/j.lfs.2011.09.024] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2011] [Revised: 08/08/2011] [Accepted: 09/28/2011] [Indexed: 11/29/2022]
Abstract
AIMS We have isolated a new muscarinic protein (MT-Mlα) from the venom of the Brazilian coral snake Micrurus lemniscatus. MAIN METHODS This small protein, which had a molecular mass of 7,048Da, shared high sequence homology with three-finger proteins that act on cholinergic receptors. The first 12 amino acid residues of the N-terminal sequence were determined to be: Leu-Ile-Cys-Phe-Ile-Cys-Phe-Ser-Pro-Thr-Ala-His. KEY FINDINGS The MT-Mlα was able to displace the [(3)H]QNB binding in the hippocampus of rats. The binding curve in competition experiments with MT-Mlα was indicative of two types of [(3)H]QNB-binding site with pK(i) values of 9.08±0.67 and 6.17±0.19, n=4, suggesting that various muscarinic acetylcholine receptor (mAChR) subtypes may be the target proteins of MT-Mlα. The MT-Mlα and the M(1) antagonist pirenzepine caused a dose-dependent block on total [(3)H]inositol phosphate accumulation induced by carbachol. The IC(50) values for MT-Mlα and pirenzepine were, respectively, 33.1 and 2.26 nM. Taken together, these studies indicate that the MT-Mlα has antagonist effect on mAChRs in rat hippocampus. SIGNIFICANCE The results of the present study show, for the first time, that mAChRs function is drastically affected by MT-Mlα since it not only has affinity for mAChRs but also has the ability to inhibit mAChRs.
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Watt ML, Schober DA, Hitchcock S, Liu B, Chesterfield AK, McKinzie D, Felder CC. Pharmacological Characterization of LY593093, an M1 Muscarinic Acetylcholine Receptor-Selective Partial Orthosteric Agonist. J Pharmacol Exp Ther 2011; 338:622-32. [DOI: 10.1124/jpet.111.182063] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023] Open
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Dasari S, Gulledge AT. M1 and M4 receptors modulate hippocampal pyramidal neurons. J Neurophysiol 2010; 105:779-92. [PMID: 21160001 DOI: 10.1152/jn.00686.2010] [Citation(s) in RCA: 103] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Acetylcholine (ACh), acting at muscarinic ACh receptors (mAChRs), modulates the excitability and synaptic connectivity of hippocampal pyramidal neurons. CA1 pyramidal neurons respond to transient ("phasic") mAChR activation with biphasic responses in which inhibition is followed by excitation, whereas prolonged ("tonic") mAChR activation increases CA1 neuron excitability. Both phasic and tonic mAChR activation excites pyramidal neurons in the CA3 region, yet ACh suppresses glutamate release at the CA3-to-CA1 synapse (the Schaffer-collateral pathway). Using mice genetically lacking specific mAChRs (mAChR knockout mice), we identified the mAChR subtypes responsible for cholinergic modulation of hippocampal pyramidal neuron excitability and synaptic transmission. Knockout of M1 receptors significantly reduced, or eliminated, most phasic and tonic cholinergic responses in CA1 and CA3 pyramidal neurons. On the other hand, in the absence of other G(q)-linked mAChRs (M3 and M5), M1 receptors proved sufficient for all postsynaptic cholinergic effects on CA1 and CA3 pyramidal neuron excitability. M3 receptors were able to participate in tonic depolarization of CA1 neurons, but otherwise contributed little to cholinergic responses. At the Schaffer-collateral synapse, bath application of the cholinergic agonist carbachol suppressed stratum radiatum-evoked excitatory postsynaptic potentials (EPSPs) in wild-type CA1 neurons and in CA1 neurons from mice lacking M1 or M2 receptors. However, Schaffer-collateral EPSPs were not significantly suppressed by carbachol in neurons lacking M4 receptors. We therefore conclude that M1 and M4 receptors are the major mAChR subtypes responsible for direct cholinergic modulation of the excitatory hippocampal circuit.
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Affiliation(s)
- Sameera Dasari
- Dartmouth Medical School, Department of Physiology and Neurobiology, One Medical Center Drive, Lebanon, NH 03756-0001, USA
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Basselin M, Rosa AO, Ramadan E, Cheon Y, Chang L, Chen M, Greenstein D, Wohltmann M, Turk J, Rapoport SI. Imaging decreased brain docosahexaenoic acid metabolism and signaling in iPLA(2)β (VIA)-deficient mice. J Lipid Res 2010; 51:3166-73. [PMID: 20686114 DOI: 10.1194/jlr.m008334] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Ca(2+)-independent phospholipase A(2)β (iPLA(2)β) selectively hydrolyzes docosahexaenoic acid (DHA, 22:6n-3) in vitro from phospholipid. Mutations in the PLA2G6 gene encoding this enzyme occur in patients with idiopathic neurodegeneration plus brain iron accumulation and dystonia-parkinsonism without iron accumulation, whereas mice lacking PLA2G6 show neurological dysfunction and neuropathology after 13 months. We hypothesized that brain DHA metabolism and signaling would be reduced in 4-month-old iPLA(2)β-deficient mice without overt neuropathology. Saline or the cholinergic muscarinic M(1,3,5) receptor agonist arecoline (30 mg/kg) was administered to unanesthetized iPLA(2)β(-/-), iPLA(2)β(+/-), and iPLA(2)β(+/+) mice, and [1-(14)C]DHA was infused intravenously. DHA incorporation coefficients k* and rates J(in), representing DHA metabolism, were determined using quantitative autoradiography in 81 brain regions. iPLA(2)β(-/-) or iPLA(2)β(+/-) compared with iPLA(2)β(+/+) mice showed widespread and significant baseline reductions in k* and J(in) for DHA. Arecoline increased both parameters in brain regions of iPLA(2)β(+/+) mice but quantitatively less so in iPLA(2)β(-/-) and iPLA(2)β(+/-) mice. Consistent with iPLA(2)β's reported ability to selectively hydrolyze DHA from phospholipid in vitro, iPLA(2)β deficiency reduces brain DHA metabolism and signaling in vivo at baseline and following M(1,3,5) receptor activation. Positron emission tomography might be used to image disturbed brain DHA metabolism in patients with PLA2G6 mutations.
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Affiliation(s)
- Mireille Basselin
- Brain Physiology and Metabolism Section, National Institute of Mental Health, National Institutes of Health, Bethesda, MD, USA
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Cardoso CC, Ricardo VP, Frussa-Filho R, Porto CS, Abdalla FMF. Effects of 17β-estradiol on expression of muscarinic acetylcholine receptor subtypes and estrogen receptor α in rat hippocampus. Eur J Pharmacol 2010; 634:192-200. [DOI: 10.1016/j.ejphar.2010.02.032] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2009] [Revised: 02/01/2010] [Accepted: 02/15/2010] [Indexed: 12/01/2022]
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M1 receptors mediate cholinergic modulation of excitability in neocortical pyramidal neurons. J Neurosci 2009; 29:9888-902. [PMID: 19657040 DOI: 10.1523/jneurosci.1366-09.2009] [Citation(s) in RCA: 100] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
ACh release into the rodent prefrontal cortex is predictive of successful performance of cue detection tasks, yet the cellular mechanisms underlying cholinergic modulation of cortical function are not fully understood. Prolonged ("tonic") muscarinic ACh receptor (mAChR) activation increases the excitability of cortical pyramidal neurons, whereas transient ("phasic") mAChR activation generates inhibitory and/or excitatory responses, depending on neuron subtype. These cholinergic effects result from activation of "M1-like" mAChRs (M1, M3, and M5 receptors), but the specific receptor subtypes involved are not known. We recorded from cortical pyramidal neurons from wild-type mice and mice lacking M1, M3, and/or M5 receptors to determine the relative contribution of M1-like mAChRs to cholinergic signaling in the mouse prefrontal cortex. Wild-type neurons in layer 5 were excited by tonic mAChR stimulation, and had biphasic inhibitory followed by excitatory, responses to phasic ACh application. Pyramidal neurons in layer 2/3 were substantially less responsive to tonic and phasic cholinergic input. Cholinergic effects were largely absent in neurons from mice lacking M1 receptors, but most were robust in neurons lacking M3, M5, or both M3 and M5 receptors. The exception was tonic cholinergic suppression of the afterhyperpolarization in layer 5 neurons, which was absent in cells lacking either M1 or M3 receptors. Finally, we confirm a role for M1 receptors in behavior by demonstrating cue detection deficits in M1-lacking mice. Together, our results demonstrate that M1 receptors facilitate cue detection behaviors and are both necessary and sufficient for most direct effects of ACh on pyramidal neuron excitability.
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Sheffler DJ, Williams R, Bridges TM, Xiang Z, Kane AS, Byun NE, Jadhav S, Mock MM, Zheng F, Lewis LM, Jones CK, Niswender CM, Weaver CD, Lindsley CW, Conn PJ. A novel selective muscarinic acetylcholine receptor subtype 1 antagonist reduces seizures without impairing hippocampus-dependent learning. Mol Pharmacol 2009; 76:356-68. [PMID: 19407080 DOI: 10.1124/mol.109.056531] [Citation(s) in RCA: 103] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023] Open
Abstract
Previous studies suggest that selective antagonists of specific subtypes of muscarinic acetylcholine receptors (mAChRs) may provide a novel approach for the treatment of certain central nervous system (CNS) disorders, including epileptic disorders, Parkinson's disease, and dystonia. Unfortunately, previously reported antagonists are not highly selective for specific mAChR subtypes, making it difficult to definitively establish the functional roles and therapeutic potential for individual subtypes of this receptor subfamily. The M(1) mAChR is of particular interest as a potential target for treatment of CNS disorders. We now report the discovery of a novel selective antagonist of M(1) mAChRs, termed VU0255035 [N-(3-oxo-3-(4-(pyridine-4-yl)piperazin-1-yl)propyl)-benzo[c][1,2,5]thiadiazole-4 sulfonamide]. Equilibrium radioligand binding and functional studies demonstrate a greater than 75-fold selectivity of VU0255035 for M(1) mAChRs relative to M(2)-M(5). Molecular pharmacology and mutagenesis studies indicate that VU0255035 is a competitive orthosteric antagonist of M(1) mAChRs, a surprising finding given the high level of M(1) mAChR selectivity relative to other orthosteric antagonists. Whole-cell patch-clamp recordings demonstrate that VU0255035 inhibits potentiation of N-methyl-D-aspartate receptor currents by the muscarinic agonist carbachol in hippocampal pyramidal cells. VU0255035 has excellent brain penetration in vivo and is efficacious in reducing pilocarpine-induced seizures in mice. We were surprised to find that doses of VU0255035 that reduce pilocarpine-induced seizures do not induce deficits in contextual freezing, a measure of hippocampus-dependent learning that is disrupted by nonselective mAChR antagonists. Taken together, these data suggest that selective antagonists of M(1) mAChRs do not induce the severe cognitive deficits seen with nonselective mAChR antagonists and could provide a novel approach for the treatment certain of CNS disorders.
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Affiliation(s)
- Douglas J Sheffler
- Department of Pharmacology, Vanderbilt University Medical Center, Nashville, TN 37232, USA
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du Bois TM, Newell KA, Han M, Deng C, Huang XF. Perinatal PCP treatment alters the developmental expression of prefrontal and hippocampal muscarinic receptors. Prog Neuropsychopharmacol Biol Psychiatry 2009; 33:37-40. [PMID: 18940225 DOI: 10.1016/j.pnpbp.2008.10.001] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/16/2008] [Revised: 10/01/2008] [Accepted: 10/01/2008] [Indexed: 10/21/2022]
Abstract
Perinatal phencyclidine (PCP) treatment has been used to model brain pathological processes that may be present in schizophrenia such as increased apoptosis during early brain development, and long-term alterations in expression of parvalbumin-containing interneurons and glutamatergic N-methyl-D-aspartate (NMDA) receptors. We report that this treatment also affects receptor expression of another excitatory neurotransmitter receptor, the muscarinic receptor. Female rat pups received injections of the NMDA receptor antagonist PCP (10 mg/kg, s.c.) or saline on postnatal days (PN)7, 9 and 11. [3H]Pirenzepine binding to M1/4 receptors was examined at four time-points (PN12, 18, 32 and 96) following treatment cessation. Significant effects of treatment on [3H]pirenzepine binding were evident immediately after treatment cessation with a decrease in PCP-treated rats at PN12 in the prefrontal cortex (-24%, p<0.05) and hippocampus (-19%, p<0.05). After this initial decrease, binding subsequently increased to 47% above control levels in the prefrontal cortex of adolescent animals, which remained elevated in adulthood (+10%, p<0.05), while in the hippocampus there was a trend towards increased binding in adolescent animals and no change thereafter. This work adds to findings demonstrating that perinatal PCP exposure leads to long-term imbalance of excitatory and inhibitory neurotransmitter systems, supporting its relevance as a developmental model of schizophrenia pathology. Alterations in muscarinic receptor expression may contribute specifically to the cognitive impairments reported to occur after perinatal NMDA receptor antagonist treatment.
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Siegel JA, Benice TS, Van Meer P, Park BS, Raber J. Acetylcholine receptor and behavioral deficits in mice lacking apolipoprotein E. Neurobiol Aging 2009; 32:75-84. [PMID: 19178986 DOI: 10.1016/j.neurobiolaging.2008.12.006] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2008] [Revised: 11/11/2008] [Accepted: 12/09/2008] [Indexed: 12/01/2022]
Abstract
Apolipoprotein E (apoE) is involved in the risk to develop sporadic Alzheimer's disease (AD). Since impaired central acetylcholine (ACh) function is a hallmark of AD, apoE may influence ACh function by modulating muscarinic ACh receptors (mAChRs). To test this hypothesis, mAChR binding was measured in mice lacking apoE and wild type C57BL/6J mice. Mice were also tested on the pre-pulse inhibition, delay eyeblink classical conditioning, and 5-choice serial reaction time tasks (5-SRTT), which are all modulated by ACh transmission. Mice were also given scopolamine to challenge central mAChR function. Compared to wild type mice, mice lacking apoE had reduced number of cortical and hippocampal mAChRs. Scopolamine had a small effect on delay eyeblink classical conditioning in wild type mice but a large effect in mice lacking apoE. Mice lacking apoE were also unable to acquire performance on the 5-SRTT. These results support a role for apoE in ACh function and suggest that modulation of cortical and hippocampal mAChRs might contribute to genotype differences in scopolamine sensitivity and task acquisition. Impaired apoE functioning may result in cholinergic deficits that contribute to the cognitive impairments seen in AD.
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Affiliation(s)
- Jessica A Siegel
- Department of Behavioral Neuroscience, Oregon Health & Science University, 8131 SW Sam Jackson Park Road, Portland, OR 97239, USA.
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Scarr E, Dean B. Muscarinic receptors: do they have a role in the pathology and treatment of schizophrenia? J Neurochem 2008; 107:1188-95. [PMID: 18957051 DOI: 10.1111/j.1471-4159.2008.05711.x] [Citation(s) in RCA: 73] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
The high affinity of antipsychotic drugs for the dopamine D2 receptor focused attention onto the role of these receptors in the genesis of psychoses and the pathology of schizophrenia. However, psychotic symptoms are only one aspect of the complex symptom profile associated with schizophrenia. Therefore, research continues into other neurochemical systems and their potential roles in key features associated with schizophrenia. Modulating the cholinergic system in attempts to treat schizophrenia predates specific neurochemical hypotheses of the disorder. Cholinergic modulation has progressed from the use of coma therapy, through the use of anti-cholinergic drugs to control side-effects of older (typical) antipsychotic medications, to the development of drugs designed to specifically activate selected muscarinic receptors. This review presents data implicating a decrease in muscarinic receptors, particularly the M1 receptor, in the pathology of schizophrenia and explores the potential physiological consequences of such a change, drawing on data available from muscarinic receptor knockout mice as well as clinical and pre-clinical pharmacology. The body of evidence presented suggests that deficits in muscarinic receptors are associated with some forms of schizophrenia and that targeting these receptors could prove to be of therapeutic benefit to patients with the disorder.
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Affiliation(s)
- Elizabeth Scarr
- Rebecca L. Cooper Research Laboratories, Mental Health Research Institute, Parkville, Vic., Australia.
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Coactivation of M(1) muscarinic and alpha1 adrenergic receptors stimulates extracellular signal-regulated protein kinase and induces long-term depression at CA3-CA1 synapses in rat hippocampus. J Neurosci 2008; 28:5350-8. [PMID: 18480291 DOI: 10.1523/jneurosci.5058-06.2008] [Citation(s) in RCA: 50] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Intact cholinergic innervation from the medial septum and noradrenergic innervation from the locus ceruleus are required for hippocampal-dependent learning and memory. However, much remains unclear about the precise roles of acetylcholine (ACh) and norepinephrine (NE) in hippocampal function, particularly in terms of how interactions between these two transmitter systems might play an important role in synaptic plasticity. Previously, we reported that activation of either muscarinic M(1) or adrenergic alpha1 receptors induces activity- and NMDA receptor-dependent long-term depression (LTD) at CA3-CA1 synapses in acute hippocampal slices, referred to as muscarinic LTD (mLTD) and norepinephrine LTD (NE LTD), respectively. In this study, we tested the hypothesis that mLTD and NE LTD are independent forms of LTD, yet require activation of a common Galphaq-coupled signaling pathway for their induction, and investigated the net effect of coactivation of M(1) and alpha1 receptors on the magnitude of LTD induced. We find that neither mLTD nor NE LTD requires phospholipase C activation, but both plasticities are prevented by inhibiting the Src kinase family and extracellular signal-regulated protein kinase (ERK) activation. Interestingly, LTD can be induced when M(1) and alpha1 agonists are coapplied at concentrations too low to induce LTD when applied separately, via a summed increase in ERK activation. Thus, because ACh and NE levels in vivo covary, especially during periods of memory encoding and consolidation, cooperative signaling through M(1) and alpha1 receptors could function to induce long-term changes in synaptic function important for cognition.
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Effects of estrogen on intracellular signaling pathways linked to activation of muscarinic acetylcholine receptors and on acetylcholinesterase activity in rat hippocampus. Biochem Pharmacol 2008; 75:1827-34. [DOI: 10.1016/j.bcp.2008.01.016] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2007] [Revised: 01/24/2008] [Accepted: 01/25/2008] [Indexed: 11/20/2022]
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Salah-Uddin H, Thomas DR, Davies CH, Hagan JJ, Wood MD, Watson JM, Challiss RAJ. Pharmacological assessment of m1 muscarinic acetylcholine receptor-gq/11 protein coupling in membranes prepared from postmortem human brain tissue. J Pharmacol Exp Ther 2008; 325:869-74. [PMID: 18322150 DOI: 10.1124/jpet.108.137968] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Using a selective Galpha(q/11) protein antibody capture guanosine 5'-O-(3-[35S]thio)triphosphate ([35S]GTPgammaS) binding approach, it has been possible to perform a quantitative pharmacological examination of the functional activity of the M(1) muscarinic acetylcholine receptor (mAChR) in membranes prepared from human postmortem cerebral cortex. Oxotremorine-M caused a > or = 2-fold increase in [35S]GTPgammaS-Galpha(q/11) binding with a pEC(50) of 6.06 +/- 0.16 in Brodmann's areas 23 and 25 that was almost completely inhibited by preincubation of membranes with the M(1) mAChR subtype-selective antagonist muscarinic toxin-7. In addition, the orthosteric and allosteric agonists, xanomeline [3(3-hexyloxy-1,2,5-thiadiazol-4-yl)-1,2,5,6-tetrahydro-1-methylpyridine] and AC-42 (4-n-butyl-1-[4-(2-methylphenyl)-4-oxo-1-butyl]-piperidine hydrogen chloride), increased [35S]-GTPgammaS-Galpha(q/11) binding, but with reduced intrinsic activities, inducing maximal responses that were 42 +/- 1 and 44 +/- 2% of the oxotremorine-M-induced response, respectively. These data indicate that the M(1) receptor is the predominant mAChR subtype coupling to the Galpha(q/11) G protein in these brain regions and that it is possible to quantify the potency and intrinsic activity of full and partial M(1) mAChR receptor agonists in postmortem human brain using a selective Galpha(q/11) protein antibody capture [35S]GTPgammaS binding assay.
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Affiliation(s)
- Hasib Salah-Uddin
- Department of Cell Physiology and Pharmacology, University of Leicester, Henry Wellcome Building, Lancaster Road, Leicester LE1 9HN, United Kingdom
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Gilsbach R, Hein L. Presynaptic metabotropic receptors for acetylcholine and adrenaline/noradrenaline. Handb Exp Pharmacol 2008:261-88. [PMID: 18064417 DOI: 10.1007/978-3-540-74805-2_9] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/02/2022]
Abstract
Presynaptic metabotropic receptors for acetylcholine and adrenaline/noradrenaline were first described more than three decades ago. Molecular cloning has resulted in the identification of five G protein-coupled muscarinic receptors (M(1) - M(5)) which mediate the biological effects of acetylcholine. Nine adrenoceptors (alpha(1ABD),alpha(2ABC),beta(123)) transmit adrenaline/noradrenaline signals between cells. The lack of sufficiently subtype-selective ligands has prevented identification of the physiological role and therapeutic potential of these receptor subtypes for a long time. Recently, mouse lines with targeted deletions for all muscarinic and adrenoceptor genes have been generated. This review summarizes the results from these gene-targeting studies with particular emphasis on presynaptic auto- and heteroreceptor functions of muscarinic and adrenergic receptors. Specific knowledge about the function of receptor subtypes will enhance our understanding of the physiological role of the cholinergic and adrenergic nervous system and open new avenues for subtype-selective therapeutic strategies.
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Affiliation(s)
- Ralf Gilsbach
- Institute of Experimental and Clinical Pharmacology and Toxicology, University of Freiburg, Albertstrasse 25, 79104, Freiburg, Germany
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Willets JM, Nelson CP, Nahorski SR, Challiss RAJ. The regulation of M1 muscarinic acetylcholine receptor desensitization by synaptic activity in cultured hippocampal neurons. J Neurochem 2007; 103:2268-80. [PMID: 17908240 PMCID: PMC2658029 DOI: 10.1111/j.1471-4159.2007.04931.x] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
To better understand metabotropic/ionotropic integration in neurons we have examined the regulation of M1 muscarinic acetylcholine (mACh) receptor signalling in mature (> 14 days in vitro), synaptically-active hippocampal neurons in culture. Using a protocol where neurons are exposed to an EC(50) concentration of the muscarinic agonist methacholine (MCh) prior to (R1), and following (R2) a desensitizing pulse of a high concentration of this agonist, we have found that the reduction in M(1) mACh receptor responsiveness is decreased in quiescent (+tetrodotoxin) neurons and increased when synaptic activity is enhanced by blocking GABA(A) receptors with picrotoxin. The picrotoxin-mediated effect on M1 mACh receptor responsiveness was completely prevented by alpha-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid receptor blockade. Inhibition of endogenous G protein-coupled receptor kinase 2 by transfection with the non-G(q/11)alpha-binding, catalytically-inactive (D110A,K220R)G protein-coupled receptor kinase 2 mutant, decreased the extent of M1 mACh receptor desensitization under all conditions. Pharmacological inhibition of protein kinase C (PKC) activity, or chronic phorbol ester-induced PKC down-regulation had no effect on agonist-mediated receptor desensitization in quiescent or spontaneously synaptically active neurons, but significantly decreased the extent of receptor desensitization in picrotoxin-treated neurons. MCh stimulated the translocation of diacylglycerol- sensitive eGFP-PKCepsilon, but not Ca2+/diacylglycerol-sensitive eGFP-PKCbetaII in both the absence, and presence of tetrodotoxin. Under these conditions, MCh-stimulated eGFP-myristoylated, alanine-rich C kinase substrate translocation was dependent on PKC activity, but not Ca2+/calmodulin. In contrast, picrotoxin-driven translocation of myristoylated, alanine-rich C kinase substrate was accompanied by translocation of PKCbetaII, but not PKCepsilon, and was dependent on PKC and Ca2+/calmodulin. Taken together these data suggest that the level of synaptic activity may determine the different kinases recruited to regulate M1 mACh receptor desensitization in neurons.
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Affiliation(s)
- Jonathon M Willets
- Department of Cell Physiology and Pharmacology, University of Leicester, Leicester, UK
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Dabisch PA, Davis EA, Horsmon MS, Mioduszewski RJ. Development of Miotic Cross-Tolerance Between Pyridostigmine and Sarin Vapor. J Ocul Pharmacol Ther 2006; 22:323-32. [PMID: 17076626 DOI: 10.1089/jop.2006.22.323] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022] Open
Abstract
The organophosphorous nerve agent sarin (GB) and the carbamate pyridostigmine bromide (PB) both inhibit acetylcholinesterase (AChE), leading to overstimulation of muscarinic receptors. Both GB and PB produce miosis through stimulation of ocular muscarinic receptors. This study investigated 2 hypotheses: (1) that the miotic response to PB would decrease following repeated injections; and (2) that repeated administration of PB would result in tolerance to the miotic effect of GB vapor. Rats were injected intramuscularly with saline, 0.04 mg/kg, 0.5 mg/kg, or 1.4 mg/kg of PB twice daily for 8 consecutive days. After day 3, animals injected with 1.4 mg/kg PB developed miotic tolerance. Twenty-four (24) h following the final PB injection, the rats were exposed to GB vapor (4.0 mg/m(3)). A similar magnitude of miosis was observed in all groups after GB exposure. However, the rate of recovery of pupil size in animals pretreated with 0.5 and 1.4 mg/kg PB was significantly increased. Twenty (20) h following exposure to GB vapor, the pupils of animals pretreated with 1.4 mg/kg PB had recovered to 77% +/- 4% of their pre-exposure baseline, whereas the saline-injected controls had recovered to only 52% +/- 2% of their pre-exposure baseline. The increased rate of recovery does not appear to be a result of protection of pupillary muscarinic receptors by the higher doses of PB, as there was no longer PB present in the animal at the time of GB exposure. These results demonstrate the development of tolerance to the miotic effect of PB following repeated exposures, and also suggest that cross-tolerance between PB and GB occurs. However, because the magnitude of the response was not reduced, the PB pretreatment and its associated miotic cross-tolerance does not appear to diminish the effectiveness of miosis as a biomarker of acute exposure to nerve agent vapor.
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Affiliation(s)
- Paul A Dabisch
- U.S. Army Edgewood Chemical Biological Center, Aberdeen Proving Ground, MD 21010-5424, USA.
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Yin Y, Henzl MT, Lorber B, Nakazawa T, Thomas TT, Jiang F, Langer R, Benowitz LI. Oncomodulin is a macrophage-derived signal for axon regeneration in retinal ganglion cells. Nat Neurosci 2006; 9:843-52. [PMID: 16699509 DOI: 10.1038/nn1701] [Citation(s) in RCA: 366] [Impact Index Per Article: 20.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2006] [Accepted: 04/21/2006] [Indexed: 11/09/2022]
Abstract
The optic nerve, like most mature CNS pathways, does not regenerate after injury. Through unknown mechanisms, however, macrophage activation in the eye stimulates retinal ganglion cells (RGCs) to regenerate long axons beyond the site of optic nerve injury. Here we identify the calcium (Ca(2+))-binding protein oncomodulin as a potent macrophage-derived growth factor for RGCs and other neurons. Oncomodulin binds to rat RGCs with high affinity in a cyclic AMP (cAMP)-dependent manner and stimulates more extensive outgrowth than other known trophic agents. Depletion of oncomodulin from macrophage-conditioned media (MCM) eliminates the axon-promoting activity of MCM. The effects of oncomodulin involve downstream signaling via Ca(2+)/calmodulin kinase and gene transcription. In vivo, oncomodulin released from microspheres promotes regeneration in the mature rat optic nerve. Oncomodulin also stimulates outgrowth from peripheral sensory neurons. Thus, oncomodulin is a new growth factor for neurons of the mature central and peripheral nervous systems.
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Affiliation(s)
- Yuqin Yin
- Department of Neurosurgery and Neurobiology Program, Children's Hospital, 300 Longwood Avenue, Boston, Massachusetts 02115, USA
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Millan MJ. Multi-target strategies for the improved treatment of depressive states: Conceptual foundations and neuronal substrates, drug discovery and therapeutic application. Pharmacol Ther 2006; 110:135-370. [PMID: 16522330 DOI: 10.1016/j.pharmthera.2005.11.006] [Citation(s) in RCA: 419] [Impact Index Per Article: 23.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2005] [Accepted: 11/28/2005] [Indexed: 12/20/2022]
Abstract
Major depression is a debilitating and recurrent disorder with a substantial lifetime risk and a high social cost. Depressed patients generally display co-morbid symptoms, and depression frequently accompanies other serious disorders. Currently available drugs display limited efficacy and a pronounced delay to onset of action, and all provoke distressing side effects. Cloning of the human genome has fuelled expectations that symptomatic treatment may soon become more rapid and effective, and that depressive states may ultimately be "prevented" or "cured". In pursuing these objectives, in particular for genome-derived, non-monoaminergic targets, "specificity" of drug actions is often emphasized. That is, priority is afforded to agents that interact exclusively with a single site hypothesized as critically involved in the pathogenesis and/or control of depression. Certain highly selective drugs may prove effective, and they remain indispensable in the experimental (and clinical) evaluation of the significance of novel mechanisms. However, by analogy to other multifactorial disorders, "multi-target" agents may be better adapted to the improved treatment of depressive states. Support for this contention is garnered from a broad palette of observations, ranging from mechanisms of action of adjunctive drug combinations and electroconvulsive therapy to "network theory" analysis of the etiology and management of depressive states. The review also outlines opportunities to be exploited, and challenges to be addressed, in the discovery and characterization of drugs recognizing multiple targets. Finally, a diversity of multi-target strategies is proposed for the more efficacious and rapid control of core and co-morbid symptoms of depression, together with improved tolerance relative to currently available agents.
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Affiliation(s)
- Mark J Millan
- Institut de Recherches Servier, Centre de Recherches de Croissy, Psychopharmacology Department, 125, Chemin de Ronde, 78290-Croissy/Seine, France.
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Scheiderer CL, McCutchen E, Thacker EE, Kolasa K, Ward MK, Parsons D, Harrell LE, Dobrunz LE, McMahon LL. Sympathetic sprouting drives hippocampal cholinergic reinnervation that prevents loss of a muscarinic receptor-dependent long-term depression at CA3-CA1 synapses. J Neurosci 2006; 26:3745-56. [PMID: 16597728 PMCID: PMC6674126 DOI: 10.1523/jneurosci.5507-05.2006] [Citation(s) in RCA: 64] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Degeneration of septohippocampal cholinergic neurons results in memory deficits attributable to loss of cholinergic modulation of hippocampal synaptic circuits. A remarkable consequence of cholinergic degeneration is the sprouting of noradrenergic sympathetic fibers from the superior cervical ganglia into hippocampus. The functional impact of sympathetic ingrowth on synaptic physiology has never been investigated. Here, we report that, at CA3-CA1 synapses, a Hebbian form of long-term depression (LTD) induced by muscarinic M1 receptor activation (mLTD) is lost after medial septal lesion. Unexpectedly, expression of mLTD is rescued by sympathetic sprouting. These effects are specific because LTP and other forms of LTD are unaffected. The rescue of mLTD expression is coupled temporally with the reappearance of cholinergic fibers in hippocampus, as assessed by the immunostaining of fibers for VAChT (vesicular acetylcholine transporter). Both the cholinergic reinnervation and mLTD rescue are prevented by bilateral superior cervical ganglionectomy, which also prevents the noradrenergic sympathetic sprouting. The new cholinergic fibers likely originate from the superior cervical ganglia because unilateral ganglionectomy, performed when cholinergic reinnervation is well established, removes the reinnervation on the ipsilateral side. Thus, the temporal coupling of the cholinergic reinnervation with mLTD rescue, together with the absence of reinnervation and mLTD expression after ganglionectomy, demonstrate that the autonomic-driven cholinergic reinnervation is essential for maintaining mLTD after central cholinergic cell death. We have discovered a novel phenomenon whereby the autonomic and central nervous systems experience structural rearrangement to replace lost cholinergic innervation in hippocampus, with the consequence of preserving a form of LTD that would otherwise be lost as a result of cholinergic degeneration.
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