Selective agonists of the M1 subtype of muscarinic acetylcholine receptor (mAChR) may provide a novel approach for treatment of both psychosis and cognitive disturbances in patients suffering from schizophrenia and other CNS disorders. Unfortunately, previous efforts to develop highly selective M1 receptor agonists have failed because of the high conservation of the orthosteric ACh binding site across all mAChR subtypes. We have now developed highly selective activators of the M1 receptor that have no activity at any other mAChR subtype. The key to achieving this unprecedented selectivity was to target allosteric sites on M1 rather than developing traditional agonists acting at the highly conserved ACh binding site. These novel M1 allosteric activators have excellent pharmacokinetic properties and brain penetration. Furthermore, preliminary studies suggest that representative compounds have efficacy in animal models that predict antipsychotic and cognition-enhancing effects. Interestingly, structurally distinct M1-selective allosteric activators can differentially regulate coupling of M1 to various signaling pathways. For instance, a compound termed BQCA increases M1 activation of phospholipase C (PLC), calcium mobilization, and recruitment of 2- arrestin proteins to the cell membrane. In contrast, two other M1 allosteric agonists, activate M1 coupling to PLC and calcium mobilization but do not induce 2-arrestin recruitment. In addition, our studies suggest that these agents may differentially regulate coupling of M1 to protein kinase pathways. These surprising findings suggest that distinct M1 allosteric activators could have fundamentally different effects on CNS function and could differ in their potential therapeutic utility. Thus, it will be critical to fully understand the effects of different M1-selective allosteric modulators on coupling of M1 to different signaling pathways and to determine how this relates to electrophysiological effects of these agents and effects in animal models that predict efficacy in treatment of different domains of schizophrenia. We will perform a series of studies in to systematically determine the effects of representative M1 allosteric activators on cell signaling and electrophysiological responses in forebrain neurons important for antipsychotic and cognition-enhancing effects of these agents. In addition, we will determine the behavioral effects of M1 allosteric activators in rodent models that predict antipsychotic and cognition-enhancing effects. These studies will allow us to rigorously test the hypothesis that selective allosteric activators of M1 have effects in animal models that predict efficacy as novel antipsychotic and cognition-enhancing agents. In addition, we will determine whether the electrophysiological and behavioral effects of specific M1 allosteric activators vary depending on the effects of the novel compounds on coupling of M1 to specific cell signaling pathways.

Public Health Relevance

Studies in patients suffering from the schizophrenia suggest that drugs that selectively activate a specific receptor for the neurotransmitter acetylcholine may provide a novel approach for treatment of this debilitating brain disorder. We have discovered new drug like molecules that selectively activate with this neurotransmitter receptor. Studies are proposed to test the hypothesis that these novel molecules have actions that predict efficacy in treatment of schizophrenia.

Agency
National Institute of Health (NIH)
Institute
National Institute of Mental Health (NIMH)
Type
Research Project (R01)
Project #
5R01MH073676-08
Application #
8391749
Study Section
Pathophysiological Basis of Mental Disorders and Addictions Study Section (PMDA)
Program Officer
Brady, Linda S
Project Start
2005-04-01
Project End
2015-11-30
Budget Start
2012-12-13
Budget End
2013-11-30
Support Year
8
Fiscal Year
2013
Total Cost
$407,793
Indirect Cost
$146,387
Name
Vanderbilt University Medical Center
Department
Pharmacology
Type
Schools of Medicine
DUNS #
004413456
City
Nashville
State
TN
Country
United States
Zip Code
37212
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Kurata, Haruto; Gentry, Patrick R; Kokubo, Masaya et al. (2015) Further optimization of the M5 NAM MLPCN probe ML375: tactics and challenges. Bioorg Med Chem Lett 25:690-4
Garcia, Raphael Caio Tamborelli; Dati, Livia Mendonça Munhoz; Torres, Larissa Helena et al. (2015) M1 and M3 muscarinic receptors may play a role in the neurotoxicity of anhydroecgonine methyl ester, a cocaine pyrolysis product. Sci Rep 5:17555
Conn, P Jeffrey; Lindsley, Craig W; Meiler, Jens et al. (2014) Opportunities and challenges in the discovery of allosteric modulators of GPCRs for treating CNS disorders. Nat Rev Drug Discov 13:692-708

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