M1 Muscarinic Acetylcholine Research Articles

Functional activity of the muscarinic positive allosteric modulator VU319 during a Phase 1 Single Ascending Dose study

<h3>Introduction</h3> The development of neurotransmitter based cognitive enhancers for Alzheimer's disease have focused recently on allosteric modulation, as a way of reducing potential drug-limiting toxicities that have been the hallmark of earlier orthosteric compounds. VU319 is an investigational positive allosteric modulator of the M1 muscarinic acetylcholine receptor that has recently finished initial testing in healthy volunteers. Cognitive tasks and event-related potentials (ERPs) have been used during the randomized, double-blind, placebo controlled Single Ascending Dose (SAD) study of VU319. This presentation includes both data from the initial SAD study, and the Food Effect substudy. The main pharmacodynamic objectives of the SAD were to identify early markers of functional engagement. Following the ascending dose cohorts, a Food Effect substudy was conducted to assess whether there was any change in the cognitive performance if VU319 was dosed with food compared to in a fasted state. <h3>Methods</h3> VU319 was given orally to 52 healthy volunteers aged 18-55 years. The SAD study tested 40 participants in five dose escalating cohorts of eight participants, in which six received VU319 and two received placebo. The Food Effect substudy consisted of 12 participants, in which ten received oral VU319 and two received placebo. The five doses for the SAD study were 60, 120, 240, 400 and 600mg. Participants in the Food Effect substudy received VU319 at a single dose of 120mg. For the 5 cohorts of the SAD study, all participants were dosed in a fasted stated. In contrast, all 12 participants in the Food Effect substudy completed were dosed twice; once fasted, and once following breakfast. Cognitive and electrophysiological tasks were examined pre-dosing and at 5 hours post-dose. The tasks were selected for their sensitivity to cholinergic tone. Cognitive tasks tested spatial and sustained attention, episodic and working memory, perceptual vigilance and psychomotor speed. Recorded ERP examined auditory and visual discrimination using oddball tasks, and an incidental memory task in which participants passively observed novel and repeated complex images. <h3>Results</h3> The analysis showed a trend for improvements in cognitive and ERP performance on the higher doses of VU319 compared to placebo. Participants on the highest dose of VU319 responded significantly faster to targets on the continuous performance test compared to participants on placebo (p = 0.03, effect size d = 1.2). Additionally, on the incidental memory task, participants who received the higher two doses of VU319 exhibited larger P300 amplitudes compared to placebo, when present with repeated compared to novel images (d > 0.8). Examination of the relationship between plasma levels of VU319 and cognitive performance showed that the response time on the continuous performance task decreased in relation to increasing concentration of VU319 in the bloodstream. <h3>Conclusions</h3> We conclude that these results demonstrate potential enhancement of the cholinergic system functioning in healthy adults following a single dose of VU319. These results provide an indication of the potential measures that are sensitive to cognitive activity by VU319 and therefore provide a potential framework to examine the cognitive impact of multiple doses of VU319 in AD patients. <h3>Funding</h3> This work was supported by funding from the Alzheimer's Association Part the Cloud Initiative PCTR-16-383171.

Synthesis and anticancer evaluation of 6-azacyclonol-2,4,6-trimethylpyridin-3-ol derivatives: M3 muscarinic acetylcholine receptor-mediated anticancer activity of a cyclohexyl derivative in androgen-refractory prostate cancer

We recently reported 2,4,5-trimethylpyridin-3-ol with C(6)-azacyclonol, whose code name is BJ-1207, showing a promising anticancer activity by inhibiting NOX-derived ROS in A549 human lung cancer cells. The present study was focused on structural modification of the azacyclonol moiety of BJ-1207 to find a compound with better anticancer activity. Ten new compounds (3A–3J) were prepared and evaluated their inhibitory actions against proliferation of eighteen cancer cell lines as a primary screening. Among the ten derivatives of BJ-1207, the effects of compounds 3A and 3J on DU145 and PC-3, androgen-refractory cancer cell lines (ARPC), were greater than the parent compound, and compound 3A showed better activity than 3J. Antitumor activity of compound 3A was also observed in DU145-xenografted chorioallantoic membrane (CAM) tumor model. In addition, the ligand-based target prediction and molecular docking study using DeepZema® server showed compound 3A was a ligand to M3 muscarinic acetylcholine receptor (M3R) which is overexpressed in ARPC. Carbachol, a muscarinic receptor agonist, concentration dependently increased proliferation of DU145 in the absence of serum, and it also activated NADPH oxidase (NOX). The carbachol-induced proliferation and NOX activity was significantly blocked by compounds 3A in a concentration-dependent manner. This finding might become a new milestone in the development of pyridinol-based anti-cancer agents against ARPC.

McN-A-343, a muscarinic agonist, reduces inflammation and oxidative stress in an experimental model of ulcerative colitis

AimThe aim of the present study was to investigate the anti-inflammatory response mediated of the M1 muscarinic acetylcholine receptor (mAChR) during experimental colitis. Material and methodsAfter the induction of 6% acetic acid colitis, mice were treated with McN-A-343 0.5, 1.0, and 1.5 mg/kg or dexamethasone (DEXA, 2.0 mg/kg) or pirenzepine (PIR, 10 mg/kg; M1 mAChR antagonist). Colonic inflammation was assessed by macroscopic and microscopic lesion scores, colonic wet weight, myeloperoxidase (MPO) activity, interleukin-1 beta (IL1-β) levels and tumor necrosis factor alpha (TNF-α), glutathione (GSH), malondialdehyde (MDA) and nitrate and nitrite (NO3/NO2), mRNA expression of IKKα, nuclear factor kappa beta (NF-kB) and cyclooxygenase-2 (COX-2), as well protein expression of NF-kB and COX-2. ResultsTreatment with McN-A-343 at a concentration of 1.5 mg/kg showed a significant reduction in intestinal damage as well as a decrease in wet weight, MPO activity, pro-inflammatory cytokine concentration, markers of oxidative stress and expression of inflammatory mediators. The action of the M1 agonist by the administration of pirenzepine, which promoted the blocking of the mAChR M1-mediated anti-inflammatory response, has also been proven. ConclusionThe results suggest that peripheral colonic M1 mAChR is involved in reversing the pro-inflammatory effect of experimentally induced colitis, which may represent a promising therapeutic alternative for patients with ulcerative colitis.

Fine Tuning Muscarinic Acetylcholine Receptor Signaling Through Allostery and Bias.

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.

The decrease in hippocampal transient receptor potential M2 (TRPM2) channel and muscarinic acetylcholine receptor 1 (CHRM1) is associated with memory loss in a surgical menopause rat model

IntroductionThe aim of the study was to investigate the association of transient receptor potential M2 (TRPM2) channel and muscarinic acetylcholine receptor 1 (CHRM1) activity with the memorial functions that are deteriorated in surgical menopause.Material and methodsA total of 14 female rats were randomly divided into 2 groups: group (G)1: sham group; group (G)2: surgical menopause group, the group in which bilateral ovariectomy was performed. Fourteen days after the surgical procedure, learning and memorial tests were performed in G1 and G2 for a totally 13 days. The time required for the rats to find the cheese in the labyrinth was recorded and statistical evaluation of it was performed between groups. On the 14th day of the memory test, the rats were decapitated and the brain tissues were fixed in 10% formalin. Hippocampal TRPM2 and CHRM1 gene expression was evaluated with RNA isolation, complementary DNA (cDNA) synthesis and quantitative real-time PCR (qRT-PCR) analysis. TRPM2 and CHRM1 immunoreactivity was evaluated in hippocampal tissue with the immunohistochemical method. Histo-score was calculated regarding the diffuseness of and severity of the staining; and statistical analyses were performed.ResultsIn the ovariectomized group, the mean time required for the rats to find the cheese was statistically significantly elongated (39.29 ±4.0 s vs. 29.86 ±2.6 s). When the hippocampal TRPM2 and CHRM1 gene expression and immunoreactivity were compared with the sham group, there was a statistically significant decrease in the surgical menopause group (p < 0.05).ConclusionsIn surgical menopause, in deterioration of memorial functions, hippocampal TRPM2 channel and CHRM1 activity plays an important role.

M1 muscarinic acetylcholine receptor-mediated inhibition of GABA release from striatal medium spiny neurons onto cholinergic interneurons.

Acetylcholine (ACh) modulates neurotransmitter release in the central nervous system. Although GABAergic transmission onto the striatal cholinergic interneurons (ChIN) is modulated by dopamine receptors, cholinergic modulation of the same synapse is still unknown. In the present study, modulatory roles of ACh in the GABAergic transmission from striatal medium spiny neurons (MSNs) onto ChIN were investigated using optogenetics and whole-cell patch-clamp technique in juvenile and young-adult mice brain slices. GABAA receptor-mediated inhibitory postsynaptic currents (IPSCs) were evoked by focal electrical- or blue-light stimulation. Bath application of carbachol, a muscarinic ACh receptor agonist, suppressed the amplitude of IPSCs in a concentration-dependent manner in both age groups. A choline esterase inhibitor, physostigmine, also suppressed the amplitude of IPSCs. In the presence of a membrane permeable M1 muscarine receptor antagonist, pirenzepine, carbachol-induced suppression of IPSCs was antagonized, whereas a M2 muscarine receptor antagonist, a M4 receptor antagonist, or a membrane impermeable M1 receptor antagonist did not antagonize carbachol-induced suppression of IPSCs. Retrograde cannabinoid cascade via cannabinoid receptor 1 was not involved in carbachol-induced inhibition. Furthermore, carbachol did not affect amplitude of inward currents induced by puff application of GABA, whereas coefficient of variation of IPSCs was significantly increased by carbachol. These results suggest that activation of presynaptic M1 muscarine receptors located on the GABAergic terminals including intracellular organelle of MSNs inhibits GABA release onto ChIN.

BRET- and fluorescence anisotropy-based assays for real-time monitoring of ligand binding to M2 muscarinic acetylcholine receptors

BRET and fluorescence anisotropy (FA) are two fluorescence-based techniques used for the characterization of ligand binding to G protein-coupled receptors (GPCRs) and both allow monitoring of ligand binding in real time. In this study, we present the first direct comparison of BRET-based and FA-based binding assays using the human M2 muscarinic acetylcholine receptor (M2R) and two TAMRA (5-carboxytetramethylrhodamine)-labeled fluorescent ligands as a model system. The determined fluorescent ligand affinities from both assays were in good agreement with results obtained from radioligand competition binding experiments. The assays yielded real-time kinetic binding data revealing differences in the mechanism of binding for the investigated fluorescent probes. Furthermore, the investigation of various unlabeled M2R ligands yielded pharmacological profiles in accordance with earlier reported data. Taken together, this study showed that BRET- and FA-based binding assays represent valuable alternatives to radioactivity-based methods for screening purposes and for a precise characterization of binding kinetics supporting the exploration of binding mechanisms.

The Role of Orthosteric Building Blocks of Bitopic Ligands for Muscarinic M1 Receptors.

The muscarinic M1 acetylcholine receptor is an important drug target for the treatment of various neurological disorders. Designing M1 receptor-selective drugs has proven challenging, mainly due to the high conservation of the acetylcholine binding site among muscarinic receptor subtypes. Therefore, less conserved and topographically distinct allosteric binding sites have been explored to increase M1 receptor selectivity. In this line, bitopic ligands, which target orthosteric and allosteric binding sites simultaneously, may provide a promising strategy. Here, we explore the allosteric, M1-selective BQCAd scaffold derived from BQCA as a starting point for the design, synthesis, and pharmacological evaluation of a series of novel bitopic ligands in which the orthosteric moieties and linker lengths are systematically varied. Since β-arrestin recruitment seems to be favorable to therapeutic implication, all the compounds were investigated by G protein and β-arrestin assays. Some bitopic ligands are partial to full agonists for G protein activation, some activate β-arrestin recruitment, and the degree of β-arrestin recruitment varies according to the respective modification. The allosteric BQCAd scaffold controls the positioning of the orthosteric ammonium group of all ligands, suggesting that this interaction is essential for stimulating G protein activation. However, β-arrestin recruitment is not affected. The novel set of bitopic ligands may constitute a toolbox to study the requirements of β-arrestin recruitment during ligand design for therapeutic usage.

Evaluation of Various Solvent Extracts of Tetrastigma leucostaphylum (Dennst.) Alston Leaves, a Bangladeshi Traditional Medicine Used for the Treatment of Diarrhea.

Tetrastigma leucostaphylum (TL) is an important ethnic medicine of Bangladesh used to treat diarrhea and dysentery. Hence, current study has been designed to characterize the antidiarrheal (in vivo) and cytotoxic (in vitro) effects of T. leucostaphylum. A crude extract was prepared with methanol (MTL) and further partitioned into n-hexane (NTL), dichloromethane (DTL), and n-butanol (BTL) fractions. Antidiarrheal activity was investigated using castor oil induced diarrhea, enteropooling, and gastrointestinal transit models, while cytotoxicity was evaluated using the brine shrimp lethality bioassay. In antidiarrheal experiments, all doses (100, 200, and 400 mg/kg) of the DTL extract significantly reduced diarrheal stool frequency, volume and weight of intestinal contents, and gastrointestinal motility in mice. Similarly, in the cytotoxicity assay, all extracts exhibited activity, with the DTL extract the most potent (LC50 67.23 μg/mL). GC-MS analysis of the DTL extract identified 10 compounds, which showed good binding affinity toward M3 muscarinic acetylcholine, 5-HT3, Gut inhibitory phosphodiesterase, DNA polymerase III subunit alpha, and UDP-N-acetylglucosamine-1 carboxyvinyltransferase enzyme targets upon molecular docking analysis. Although ADME/T analyses predicted the drug-likeness and likely safety upon consumption of these bioactive compounds, significant toxicity concerns are evident due to the presence of the known phytotoxin, 2,4-di-tert-butylphenol. In summary, T. leucostaphylum showed promising activity, helping to rationalize the ethnomedicinal use and importance of this plant, its safety profile following both acute and chronic exposure warrants further investigation.

The optimization of a novel selective antagonist for human M2 muscarinic acetylcholine receptor

Muscarinic acetylcholine receptors (mAChRs) comprise five distinct subtypes denoted M1 to M5. The antagonism of M2 subtype could increase the release of acetylcholine from vesicles into the synaptic cleft and improve postsynaptic functions in the hippocampus via M1 receptor activation, displaying therapeutic potentials for Alzheimer’s disease. However, drug development for M2 antagonists is still challenged among different receptor subtypes. In this study, by optimizing a scaffold from virtual screening, we synthesized two focused libraries and generated up to 50 derivatives. By measuring potency and binding selectivity, we discovered a novel M2 antagonist, ligand 47, featuring submicromolar IC50, high M2/M4 selectivity (~30-fold) and suitable lipophilicity (cLogP = 4.55). Further study with these compounds also illustrates the structure–activity relationship of this novel scaffold. Our study could not only provide novel lead structure, which was easy to synthesize, but also offer valuable information for further development of selective M2 ligands.

Gut microbial bile acid metabolite skews macrophage polarization and contributes to high-fat diet-induced colonic inflammation

ABSTRACT High-fat diet (HFD) leads to systemic low-grade inflammation, which has been involved in the pathogenesis of diverse metabolic and inflammatory diseases. Colon is thought to be the first organ suffering from inflammation under HFD conditions due to the pro-inflammatory macrophages infiltration, however, the mechanisms concerning the induction of pro-inflammatory phenotype of colonic macrophages remains unclear. In this study, we show that HFD increased the percentage of gram-positive bacteria, especially genus Clostridium, and resulted in the significant increment of fecal deoxycholic acid (DCA), a gut microbial metabolite produced by bacteria mainly restricted to genus Clostridium. Notably, reducing gram-positive bacteria with vancomycin diminished fecal DCA and profoundly alleviated pro-inflammatory macrophage infiltration in colon, whereas DCA-supplemented feedings to vancomycin-treated mice provoked obvious pro-inflammatory macrophage infiltration and colonic inflammation. Meanwhile, intra-peritoneal administration of DCA also elicited considerable recruitment of macrophages with pro-inflammatory phenotype. Mechanistically, DCA dose-dependently promoted M1 macrophage polarization and pro-inflammatory cytokines production at least partially through toll-like receptor 2 (TLR2) transactivated by M2 muscarinic acetylcholine receptor (M2-mAchR)/Src pathway. In addition, M2-mAchR mediated increase of TLR2 transcription was mainly achieved via targeting AP-1 transcription factor. Moreover, NF-κB/ERK/JNK signalings downstream of TLR2 are involved in the DCA-induced macrophage polarization. In conclusion, our findings revealed that high level DCA induced by HFD may serve as an initiator to activate macrophages and drive colonic inflammation, thus offer a mechanistic basis that modulation of gut microbiota or intervening specific bile acid receptor signaling could be potential therapeutic approaches for HFD-related inflammatory diseases.

Development of Novel 4-Arylpyridin-2-one and 6-Arylpyrimidin-4-one Positive Allosteric Modulators of the M1 Muscarinic Acetylcholine Receptor.

This study investigated the structure-activity relationships of 4-phenylpyridin-2-one and 6-phenylpyrimidin-4-one M1 muscarinic acetylcholine receptor (M1 mAChRs) positive allosteric modulators (PAMs). The presented series focuses on modifications to the core and top motif of the reported leads, MIPS1650 (1) and MIPS1780 (2). Profiling of our novel analogues showed that these modifications result in more nuanced effects on the allosteric properties compared to our previous compounds with alterations to the biaryl pendant. Further pharmacological characterisation of the selected compounds in radioligand binding, IP1 accumulation and β-arrestin 2 recruitment assays demonstrated that, despite primarily acting as affinity modulators, the PAMs displayed different pharmacological properties across the two cellular assays. The novel PAM 7 f is a potential lead candidate for further development of peripherally restricted M1 PAMs, due to its lower blood-brain-barrier (BBB) permeability and improved exposure in the periphery compared to lead 2.

Modulation of arousal and sleep/wake architecture by M1 PAM VU0453595 across young and aged rodents and nonhuman primates.

Degeneration of basal forebrain cholinergic circuitry represents an early event in the development of Alzheimer's disease (AD). These alterations in central cholinergic function are associated with disruptions in arousal, sleep/wake architecture, and cognition. Changes in sleep/wake architecture are also present in normal aging and may represent a significant risk factor for AD. M1 muscarinic acetylcholine receptor (mAChR) positive allosteric modulators (PAMs) have been reported to enhance cognition across preclinical species and may also provide beneficial effects for age- and/or neurodegenerative disease-related changes in arousal and sleep. In the present study, electroencephalography was conducted in young animals (mice, rats and nonhuman primates [NHPs]) and in aged mice to examine the effects of the selective M1 PAM VU0453595 in comparison with the acetylcholinesterase inhibitor donepezil, M1/M4 agonist xanomeline (in NHPs), and M1 PAM BQCA (in rats) on sleep/wake architecture and arousal. In young wildtype mice, rats, and NHPs, but not in M1 mAChR KO mice, VU0453595 produced dose-related increases in high frequency gamma power, a correlate of arousal and cognition enhancement, without altering duration of time across all sleep/wake stages. Effects of VU0453595 in NHPs were observed within a dose range that did not induce cholinergic-mediated adverse effects. In contrast, donepezil and xanomeline increased time awake in rodents and engendered dose-limiting adverse effects in NHPs. Finally, VU0453595 attenuated age-related decreases in REM sleep duration in aged wildtype mice. Development of M1 PAMs represents a viable strategy for attenuating age-related and dementia-related pathological disturbances of sleep and arousal.

Blockade of the M1 muscarinic acetylcholine receptors impairs eyeblink serial feature-positive discrimination learning in mice.

The serial feature-positive discrimination task requires the subjects to respond differentially to the identical stimulus depending on the temporal context given by a preceding cue stimulus. In the present study, we examined the involvement of the M1 muscarinic acetylcholine receptors using a selective M1 antagonist VU0255035 in the serial feature-positive discrimination task of eyeblink conditioning in mice. In this task, mice received a 2-s light stimulus as the conditional cue 5 or 6 s before the presentation of a 350-ms tone conditioned stimulus (CS) paired with a 100-ms peri-orbital electrical shock (cued trials), while they did not receive the cue before the presentation of the CS alone (non-cued trials). Each day mice randomly received 30 cued and 30 non-cued trials. We found that VU0255035 impaired acquisition of the conditional discrimination as well as the overall acquisition of the conditioned response (CR) and diminished the difference in onset latency of the CR between the cued and non-cued trials. VU0255035 administration to the control mice after sufficient learning did not impair the pre-acquired conditional discrimination or the CR expression itself. These effects of VU0255035 were almost similar to those with the scopolamine in our previous study, suggesting that among the several types of muscarinic acetylcholine receptors, the M1 receptors may play an important role in the acquisition of the conditional discrimination memory but not in mediating the discrimination itself after the memory had formed in the eyeblink serial feature-positive discrimination learning.

M3 muscarinic acetylcholine receptor-reactive Th17 cells in primary Sjögren's syndrome.

M3 muscarinic acetylcholine receptor (M3R) is one of the autoantigens associated with Sjögren's syndrome (SS) and is localized in exocrine glands where disease-specific inflammation occurs. The inflammatory lesion is characterized by infiltration of CD4+ T cells, including clonally expanded Th17 cells. We undertook this study to identify circulating M3R-specific Th17 cells and to determine functional properties of those cells. Using the enzyme-linked immunospot assay (ELISpot) method, we identified M3R-reactive Th17 cells in the peripheral blood of patients with primary SS (pSS). Among 10 examined pSS patients, 10 healthy subjects (HS), and 5 IgG4-related disease (IgG4-RD) patients, M3R-reactive IL-17 secreting cells were significantly increased in 5 pSS patients specifically. The most common T cell epitope, which was analyzed and confirmed by coculture of isolated CD4+ T cells with antigen presenting cells plus M3R peptides in vitro, was peptide 83-95 of M3R. Peptide recognition was partly in an HLA-DR-restricted manner, confirmed by blocking assay. M3R-reactive Th17 cells positivity correlated with higher titers of anti-M3R antibodies, whose systemic disease activity score tended to be higher. Our studies highlight the role of tissue-specific autoantigen-derived circulating Th17 cells in pSS, for which further work might lead to antigen-specific targeted therapy.

CHRM3 rs2165870 Polymorphism Correlates with Postoperative Nausea and Vomiting Incidence and the Efficacy of Ondansetron in a Chinese Han Population.

BackgroundPrevious GWAS studies have shown that there is a relationship between M3 muscarinic acetylcholine receptor (CHRM3) rs2165870 polymorphism and postoperative nausea and vomiting (PONV) incidence. However, no Chinese studies have addressed this issue.MethodsTo explore the relationship between CHRM3 rs2165870 polymorphism and PONV incidence in a Chinese Han population, we enrolled 512 patients receiving elective surgery in this study. CHRM3 rs2165870 polymorphism was genotyped using PCR-RFLP method.ResultsWe found that AA genotype or A allele of CHRM3 rs2165870 polymorphism elevated the risk of PONV (AA versus GG; OR, 2.88; 95% CI, 1.51–5.47; P = 0.001; A versus G; OR, 1.39; 95% CI, 1.07–1.81; P = 0.013). In addition, CHRM3 rs2165870 polymorphism was related to the risk of PONV among the males, smokers, and those individuals with Apfel Score 3–4 or ASA classification 2–3. Last, we assessed the effects of CHRM3 rs2165870 polymorphism on the treatment efficacy of ondansetron for PONV. Data uncovered that 103 of 209 patients (49.3%) showed response to ondansetron treatment for PONV. The PONV incidence was significantly higher in AA genotype carriers compared with GG genotype carriers during the first 2 h after surgery, but not from 2 to 24 h after surgery.ConclusionTo sum up, this study reveals that CHRM3 rs2165870 polymorphism is related to the incidence of PONV and treatment effects of ondansetron for preventing PONV in this Chinese Han population.

From Structure to Clinic: Discovery of A M1 Muscarinic Acetylcholine Receptor Agonist for the Treatment of Memory Loss in Alzheimer's Disease

Current therapies for improving memory in Alzheimer’s disease are focused on correcting for defective cholinergic transmission by increasing acetylcholine levels through inhibition of acetylcholinesterase enzymes. These treatments are however associated with limited clinical efficacy and dose-limiting adverse effects. Here we describe agonist-bound crystal structures of the M1 muscarinic acetylcholine receptor (M1 mAChR) and its application in supporting the rational drug design of a selective M1-orthosteric agonist, HTL0009936. On the basis of pro-cognitive effects across a range of pre-clinical animal models and a favourable safety and toxicology profile HTL0009936 was progressed to first in human trials where the agonist activated central processes corresponding to learning and memory circuitry. Hence, our study not only describes the pharmacological profile of a M1 mAChR agonist with the potential to improve memory in Alzheimer’s disease but also demonstrates how to rationally progress the development of a G protein-coupled receptor ligand from structure to clinical candidate.

The M1 muscarinic acetylcholine receptor in the crypt stem cell compartment mediates intestinal mucosal growth.

Localization of a specific subtype of the muscarinic acetylcholine receptor in the crypt stem cell compartment suggests a critical role in intestinal mucosal homeostasis. Here we demonstrate the localization of the M1 muscarinic acetylcholine receptor to the stem cell compartment and demonstrate increase morphometric and proliferative parameters when this is stimulated in vivo. These data provide novel information about this complex signaling microenvironment and offer potential future therapeutic targets for future study.

Preparation of a First 18F-Labeled Agonist for M1 Muscarinic Acetylcholine Receptors.

M1 muscarinic acetylcholine receptors (mAChRs) are abundant in postsynaptic nerve terminals of all forebrain regions and have been implicated in the cognitive decline associated with Alzheimer’s disease and other CNS pathologies. Consequently, major efforts have been spent in the development of subtype-selective positron emission tomography (PET) tracers for mAChRs resulting in the development of several 11C-labeled probes. However, protocols for the preparation of 18F-labeled mAChR-ligands have not been published so far. Here, we describe a straightforward procedure for the preparation of an 18F-labeled M1 mAChR agonist and its corresponding pinacol boronate radiolabeling precursor and the non-radioactive reference compound. The target compounds were prepared from commercially available aryl fluorides and Boc protected 4-aminopiperidine using a convergent reaction protocol. The radiolabeling precursor was prepared by a modification of the Miyaura reaction and labeled via the alcohol-enhanced Cu-mediated radiofluorination. The developed procedure afforded the radiotracer in a non-decay-corrected radiochemical yield of 17 ± 3% (n = 3) and in excellent radiochemical purity (>99%) on a preparative scale. Taken together, we developed a straightforward protocol for the preparation of an 18F-labeled M1 mAChR agonist that is amenable for automation and thus provides an important step towards the routine production of a 18F-labeled M1 selective PET tracer for experimental and diagnostic applications.

Stimulation of muscarinic acetylcholine M1 receptors reallocates choice between cocaine and an alternative reinforcer.

Stimulation of muscarinic acetylcholine M1 receptors reallocates choice between cocaine and an alternative reinforcer.