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Subtype-selective allosteric modulators of muscarinic receptors for the treatment of CNS disorders

Department of Pharmacology, Vanderbilt Program in Drug Discovery, Vanderbilt Medical Center, Nashville, TN 37232, USA.
Trends in Pharmacological Sciences (Impact Factor: 9.99). 03/2009; 30(3):148-55. DOI: 10.1016/j.tips.2008.12.002
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ABSTRACT Muscarinic acetylcholine receptors (mAChRs) have long been viewed as viable targets for novel therapeutic agents for the treatment of Alzheimer's disease (AD) and other disorders involving impaired cognitive function. More recent evidence indicates that mAChR activators might also have utility in treating psychosis and other symptoms associated with schizophrenia and other central nervous system (CNS) disorders. Efforts to develop mAChR subtype-selective agonists have been hampered by difficulty in achieving high selectivity for individual mAChR subtypes important for CNS function (M(1) and M(4)) and adverse effects due to activation of peripheral mAChRs (especially M(2) and M(3)). Major advances have now been achieved in the discovery of allosteric agonists and positive allosteric modulators of M(1) and M(4) that show greater selectivity for individual mAChR subtypes than do previous mAChR agonists. Early studies indicate that these allosteric mAChR activators have properties needed for optimization as potential clinical candidates and have robust effects in animal models that predict efficacy in the treatment of AD, schizophrenia and related disorders.

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Available from: P. Jeffrey Conn, Aug 26, 2015
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    • "According to the glutamatergic theory of schizophrenia, proposed by Javitt (1987, 2010) and developed later on by Conn et al. (2009) it seems that the ligands of the metabotropic glutamate receptors may constitute a good alternative for presently used neuroleptic therapy. The antipsychotic-like effects were observed for a variety of ligands in preclinical studies. "
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    ABSTRACT: Diverse preclinical studies exploiting the modulation of the GABAergic and/or glutamatergic system in brain via metabotropic receptors suggest their potential therapeutic utility. GS39783 and CDPPB, a positive allosteric modulators of GABAB and mGlu5 receptors, were previously shown to reverse behavioral phenotypes in animal models thought to mimic selected (predominantly positive) symptoms of schizophrenia. In the present study we investigated the activity of selected GABAB (GS39783 and CGP7930) and mGlu5 (CDPPB) positive allosteric modulators. We focused mainly on the aspects of their efficacy in the models of negative and cognitive symptoms of schizophrenia. We used modified swim test, social interactions (models of negative symptoms) and novel object recognition (model of cognitive disturbances). The activity of the compounds was also tested in haloperidol-induced catalepsy test. The mutual interaction between GABAB/mGlu5 ligands was investigated as well. In the second part of the study, DHPG-induced PI hydrolysis in the presence of GABAB receptor antagonist (SKF97541), and SKF97541-induced inhibition of cAMP formationin the presence of DHPG, were performed. Both mGlu5 and GABAB receptor modulators effectively reversed MK-801-induced deficits in behavioral models of schizophrenia. Moreover, the concomitant administration of sub-effective doses of CDPPB and GS39783, induced a clear antipsychotic-like effect in all the procedures used, except DOI-induced head twitches. The concomitant administration of group I mGlu and GABAB agonists did not displayed any synergistic effects in vitro. Summing up, an activation of both types of receptor may be a promising mechanism for the development of novel antipsychotic drugs, efficacious towards positive, negative and cognitive symptoms. Copyright © 2015. Published by Elsevier Ltd.
    Neurochemistry International 04/2015; DOI:10.1016/j.neuint.2015.03.010 · 2.65 Impact Factor
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    • "Allosteric modulators of muscarinic receptors show promise as po - tential therapies for a number of CNS disorders , including Alzheimer ' s disease and schizophrenia . Other target areas of benefit may include neuropathic and chronic pain , epilepsy , sleep disorders , Parkinson ' s disease , and movement disorders ( Conn et al . , 2009b ) . Acetylcholine signals through both muscarinic and nicotinic receptors ."
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    • "Much attention has been focused on the distribution of residues in the extracellular region and their relation to the selectivity of ligands on muscarinic acetylcholine receptors through allosteric modulation. The new information on residues has great importance in the design of new cholinergic molecules [68] [124] [125] [126] , already having been employed to develop compounds that appear to be better that the currently prescribed non-selective muscarinic acetylcholine agonists [127] . "
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    ABSTRACT: In the last few years, there have been important new insights into the structural biology of G-protein coupled receptors. It is now known that allosteric binding sites are involved in the affinity and selectivity of ligands for G-protein coupled receptors, and that signaling by these receptors involves both G-protein dependent and independent pathways. The present review outlines the physiological and pharmacological implications of this perspective for the design of new drugs to treat disorders of the central nervous system. Specifically, new possibilities are explored in relation to allosteric and orthosteric binding sites on dopamine receptors for the treatment of Parkinson's disease, and on muscarinic receptors for Alzheimer's disease. Future research can seek to identify ligands that can bind to more than one site on the same receptor, or simultaneously bind to two receptors and form a dimer. For example, the design of bivalent drugs that can reach homo/hetero-dimers of D2 dopamine receptor holds promise as a relevant therapeutic strategy for Parkinson's disease. Regarding the treatment of Alzheimer's disease, the design of dualsteric ligands for mono-oligomeric rinic receptors could increase therapeutic effectiveness by generating potent compounds that could activate more than one signaling pathway.
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