An allosteric potentiator of M4 mAChR modulates hippocampal synaptic transmission

Abstract

Muscarinic acetylcholine receptors (mAChRs) provide viable targets for the treatment of multiple central nervous system disorders. We have used cheminformatics and medicinal chemistry to develop new, highly selective M4 allosteric potentiators. VU10010, the lead compound, potentiates the M4 response to acetylcholine 47-fold while having no activity at other mAChR subtypes. This compound binds to an allosteric site on the receptor and increases affinity for acetylcholine and coupling to G proteins. Whole-cell patch clamp recordings revealed that selective potentiation of M4 with VU10010 increases carbachol-induced depression of transmission at excitatory but not inhibitory synapses in the hippocampus. The effect was not mimicked by an inactive analog of VU10010 and was absent in M4 knockout mice. Selective regulation of excitatory transmission by M4 suggests that targeting of individual mAChR subtypes could be used to differentially regulate specific aspects of mAChR modulation of function in this important forebrain structure.

Antipsychotic Drug-Like Effects of the Selective M4 Muscarinic Acetylcholine Receptor Positive Allosteric Modulator VU0152100

“…M 4 PAMs bind to an allosteric site and can increase both the affinity of M 4 for ACh and the efficiency of coupling of M 4 to G proteins (Shirey et al, 2008). Consistent with their effects in cell lines, M 4 PAMs potentiate M 4 -mediated depression of excitatory synaptic transmission at hippocampal CA1 synapses (Shirey et al, 2008). Chemical optimization of early M 4 PAMs resulted in the discovery of VU0152100 as a centrally penetrant highly selective M 4 PAM .…”

“…These efforts have led to the discovery of highly selective M 4 positive allosteric modulators (PAMs) that do not activate M 4 directly, but markedly potentiate the response of M 4 to ACh (Shirey et al, 2008;Chan et al, 2008;Brady et al, 2008). M 4 PAMs bind to an allosteric site and can increase both the affinity of M 4 for ACh and the efficiency of coupling of M 4 to G proteins (Shirey et al, 2008). Consistent with their effects in cell lines, M 4 PAMs potentiate M 4 -mediated depression of excitatory synaptic transmission at hippocampal CA1 synapses (Shirey et al, 2008).…”

“…Our group and others have identified subtype-selective mAChR ligands that activate a specific receptor subtype at sites that are less highly conserved than the orthosteric binding site of acetylcholine (ACh) and more topographically distinct, termed allosteric sites. These efforts have led to the discovery of highly selective M 4 positive allosteric modulators (PAMs) that do not activate M 4 directly, but markedly potentiate the response of M 4 to ACh (Shirey et al, 2008;Chan et al, 2008;Brady et al, 2008). M 4 PAMs bind to an allosteric site and can increase both the affinity of M 4 for ACh and the efficiency of coupling of M 4 to G proteins (Shirey et al, 2008).…”

Molecular Mechanisms of Action and In Vivo Validation of an M4 Muscarinic Acetylcholine Receptor Allosteric Modulator with Potential Antipsychotic Properties

“…This study provides novel insights into the molecular mechanisms of action of LY2033298, which, together with a related series of molecules, has recently been proposed as a novel, M 4 -mAChR-selective, tool that may provide a new avenue for the treatment of disorders such as schizophrenia (Chan et al, 2008;Shirey et al, 2008). We have defined a mechanistic basis for the differential effects of this compound on the binding of orthosteric antagonists compared with agonists such as ACh, have validated pharmacologically that both agonism and modulation by LY2033298 arise from an allosteric site that likely overlaps with the site used by prototypical mAChR modulators, have identified, for the first time, signal pathway-selective allosteric modulation at the M 4 mAChR, and validated this receptor subtype as a key target for LY2033298 in native cellular systems as well as in vivo.…”

Functional Activation of G-Proteins Coupled With Muscarinic Acetylcholine Receptors in Rat Brain Membranes

“…6, the inhibitory manner of MT3 in the present study was inconsistent with the typical competitive antagonism shown in the mAChRmediated adenylate cyclase inhibition assay in rat striatal (33) (36). Among them, VU 10010 is particularly useful in investigations of M 4 mAChRs because this compound has been shown to act as a highly selective allosteric potentiator at the M 4 subtype with no activity at any other mAChR subtypes (9). In the present study, VU 10010 potentiated the effects of CCh, by leftward shifting of the concentration-response curve as well as by enhancing the maximal response.…”