The Journal of Neuroscience, October 8, 2008, 28(41):10422-10433; doi:10.1523/JNEUROSCI.1850-08.2008
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Neurobiology of Disease
Novel Selective Allosteric Activator of the M1 Muscarinic Acetylcholine Receptor Regulates Amyloid Processing and Produces Antipsychotic-Like Activity in Rats
Carrie K. Jones,1,5
Ashley E. Brady,1,5
Albert A. Davis,8
Zixiu Xiang,1
Michael Bubser,3
Mohammed Noor Tantawy,6
Alexander S. Kane,1
Thomas M. Bridges,1
J. Phillip Kennedy,2
Stefania R. Bradley,7
Todd E. Peterson,4,6
M. Sib Ansari,4,6
Ronald M. Baldwin,4,6
Robert M. Kessler,4
Ariel Y. Deutch,1,3
James J. Lah,8
Allan I. Levey,8
Craig W. Lindsley,1,2,5 and
P. Jeffrey Conn1,5
Departments of 1Pharmacology, 2Chemistry, 3Psychiatry, and 4Radiology and Radiological Sciences/PET Chemistry, 5Vanderbilt Program in Drug Discovery, and 6Vanderbilt University Institute of Imaging Science, Vanderbilt University Medical Center, Nashville, Tennessee 37232, 7ACADIA Pharmaceuticals, San Diego, California 92121, and 8Center for Neurodegenerative Disease and Department of Neurology, Emory University, Atlanta, Georgia 30322
Correspondence should be addressed to Dr. P. Jeffrey Conn, Director, Vanderbilt Program in Drug Discovery, Department of Pharmacology, Vanderbilt University Medical Center, 2220 Pierce Avenue, 1215 Light Hall, Nashville, TN 37232-6600. Email: jeff.conn{at}vanderbilt.edu
Recent studies suggest that subtype-selective activators of M1/M4 muscarinic acetylcholine receptors (mAChRs) may offer a novel approach for the treatment of psychotic symptoms associated with schizophrenia and Alzheimer's disease. Previously developed muscarinic agonists have provided clinical data in support of this hypothesis, but failed in clinical development because of a lack of true subtype specificity and adverse effects associated with activation of other mAChR subtypes. We now report characterization of a novel highly selective agonist for the M1 receptor with no agonist activity at any of the other mAChR subtypes, termed TBPB [1-(1'-2-methylbenzyl)-1,4'-bipiperidin-4-yl)-1H-benzo[d]imidazol-2(3H)-one]. Mutagenesis and molecular pharmacology studies revealed that TBPB activates M1 through an allosteric site rather than the orthosteric acetylcholine binding site, which is likely critical for its unprecedented selectivity. Whole-cell patch-clamp recordings demonstrated that activation of M1 by TBPB potentiates NMDA receptor currents in hippocampal pyramidal cells but does not alter excitatory or inhibitory synaptic transmission, responses thought to be mediated by M2 and M4. TBPB was efficacious in models predictive of antipsychotic-like activity in rats at doses that did not produce catalepsy or peripheral adverse effects of other mAChR agonists. Finally, TBPB had effects on the processing of the amyloid precursor protein toward the non-amyloidogenic pathway and decreased Aβ production in vitro. Together, these data suggest that selective activation of M1 may provide a novel approach for the treatment of symptoms associated with schizophrenia and Alzheimer's disease.
Key words: TBPB; M1 allosteric agonist; muscarinic acetylcholine receptors; schizophrenia; Alzheimer's disease; mAChR
Received April 27, 2008;
revised July 20, 2008;
accepted July 30, 2008.
Correspondence should be addressed to Dr. P. Jeffrey Conn, Director, Vanderbilt Program in Drug Discovery, Department of Pharmacology, Vanderbilt University Medical Center, 2220 Pierce Avenue, 1215 Light Hall, Nashville, TN 37232-6600. Email: jeff.conn{at}vanderbilt.edu
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