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Characterization and localization of the muscarinic cholinergic receptor in human prostatic tissue.

Radioligand receptor binding and autoradiography were used to characterize and localize the muscarinic cholinergic receptor in human benign prostatic hyperplastic tissue. These methods have not been used previously to investigate the autonomic innervation of the human prostate. The binding of [3H]N-methylscopolamine ([3H]NMS), a muscarinic cholinergic antagonist, to homogenates of human prostate was saturable and of high affinity. The equilibrium dissociation constant, (Kd), for [3H]NMS binding to human prostate homogenates was 0.10 +/- 0.03 nM (mean +/- SEM). The values of the Kd's for [3H]NM

Electroconvulsive shock and brain muscarinic receptors: relationship to anterograde amnesia.

Rats were administered one electroconvulsive shock daily for 7 days (ECS X 7) and were killed 24 hours after the last treatment. Muscarinic cholinergic receptor number, as determined by [3H] quinuclidinyl benzilate [( 3H]QNB) binding, was significantly reduced in the cerebral cortex. A parallel group of rats was trained on a passive avoidance task 24 hours following the last ECS and tested for retention of the original avoidance response 24 hours later; these animals exhibited a profound amnesia. Animals tested 1 hour following training were not amnestic, indicating that learning was unimpaire

Muscarinic antagonists induce different receptor conformations in rat adenohypophysis.

We have employed a method based on ligand competition experiments, which is capable of detecting interactions among ligand-occupied binding sites, to study the interactions between rat adenohypophysis muscarinic receptors occupied by several muscarinic antagonists. In this method, one examines the binding of a labeled ligand (the primary ligand) in the absence and presence of a competing ligand. The inhibition of binding of the primary ligand by the competing ligand shows significant deviations from that expected assuming a population of noninteracting, heterogeneous binding sites. The deviati

Two populations of binding sites for muscarinic antagonists in the rat heart.

In a medium containing 100 mM NaCl and 10 mM MgCl2, the binding of antagonists to rat myocardial muscarinic receptors is well described by the simple Langmuir isotherm. However, in low ionic strength media, while a small proportion of the sites (23%) display a small (2-3 fold) increase in antagonist affinity, the majority demonstrate a substantial (ca. 10-fold) decrease. This reduction is reversed by micromolar concentrations of guanylylimidodiphosphate and other GTP analogues, with consequent abolition of the heterogeneity of the receptor population induced by low ionic strength. Millimolar c

Tricyclic antidepressant drugs as antagonists of muscarinic receptors in sympathetic ganglia.

Close arterial injection of McN-A-343 into the superior cervical ganglion of the cat resulted in contractions of the nictitating membrane. The ganglionic effects of McN-A-343 but not those of DMPP were antagonized in a dose-related manner by 2-10 mug of desipramine, imipramine, chlorimpramine, iprindole and viloxazine. No correlation was found between the dose of each drug which blocked the effects of McN-A-343 and that required to potentiate the responses of the nictitating membrane to intra-arterial administration of noradrenaline. It is concluded that clinically effective antidepressant age

Different muscarine receptors mediate the prejunctional inhibition of [3H]-noradrenaline release in rat or guinea-pig iris and the contraction of the rabbit iris sphincter muscle.

To investigate the muscarine receptor type mediating inhibition of [3H]-noradrenaline release from the isolated rat and guinea-pig iris we have determined the potency of antimuscarinic drugs to antagonize the methacholine-induced inhibition of [3H]-noradrenaline overflow evoked by field stimulation (3 Hz, 2 min). The prejunctional apparent affinities were compared with those obtained for postjunctional muscarine receptors mediating the methacholine-induced contraction of the isolated rabbit iris sphincter muscle. Prejunctional apparent affinity constants of pirenzepine (6.67), himbacine (8.51)…

Synthesis and Pharmacological Characterization of Novel Tetrahydropyridine-Based Muscarinic M5 Receptor Antagonists to Investigate the Difference in the SARs of Muscarinic Receptor Subtypes Utilizing Induced Fit Docking Studies.

Many studies and experiments suggest the muscarinic M5 receptor (M5R) as a potential target for the clinical treatment of drug abuse, schizophrenia, or Alzheimer's disease. In the present study, a library containing 39 novel hM5R antagonists based on an arecaidine (tetrahydropyridine) core was synthesized, pharmacologically characterized in radioligand competition binding or mini-G protein assays and analyzed in molecular docking studies to elucidate their binding modes and in vitro characteristics. Compound 56m showed low single-digit nanomolar affinity on hM5R combined with a 17-fold selecti

Nobiletin differentially regulates muscarinic and nicotinic receptor-mediated ERK signaling.

Nobiletin, a citrus polymethoxyflavone with neuroprotective properties, activates extracellular signal-regulated kinase 1/2 (ERK1/2); however, its effects on cholinergic receptor-mediated ERK signaling remain unclear. This study aimed to investigate the effects of nobiletin on the muscarinic and nicotinic receptor-dependent ERK signaling in neuronal nitric oxide synthase-expressing PC12 cells. The results showed that nobiletin inhibited acetylcholine- and bethanechol-induced ERK1/2 phosphorylation, an effect attenuated by increasing agonist concentrations, consistent with a competitive-like pa

Long-acting muscarinic antagonists (LAMA) in asthma: What is the best strategy?

The use of long-acting muscarinic antagonists (LAMA) in asthma is supported by their mechanism of action and evidence of drug synergy with inhaled corticosteroids ± long-acting β-agonists. This review discusses the scientific rationale, clinical data, and recommendations for the use of LAMA in the asthma therapeutic strategy. Adding a LAMA to a dual therapy with an inhaled corticosteroid and long-acting β-agonist has been shown to reduce exacerbations, increase asthma control, and improve quality of life, with a good safety profile. In addition, using a single inhaler device containing multipl

Chlorpromazine induces hyposalivation by inhibiting muscarinic Ca2+ signaling in salivary glands.

Chlorpromazine (CPZ), a dopamine D2 receptor antagonist, is an antipsychotic drug widely used in the treatment of schizophrenia. While CPZ is known to induce hyposalivation, the exact mechanism by which it inhibits secretory function in the salivary glands remains unclear. In this study, we investigated the molecular mechanism underlying CPZ-induced hyposalivation. Our findings confirmed that CPZ decreases salivation by inhibiting muscarinic signaling in a dose-dependent manner in a mouse model. By analyzing a single-cell RNA sequencing (scRNA-seq) database, we searched known CPZ targets in sa

Усиление ремиэлизации в множестве склероза через M1 Muscarinic ацетилхолиновый рецептор.

Растет распространенность склероза (MS), однако по-прежнему требуется лечение, способное обратить вспять прогресс в развитии болезни. Одна из стратегий, которая продемонстрировала многообещающее изменение режима MS, заключается в воспрещении рецептора M1 — члена семейства мускаринических ацетилхолинов (mAChR). Считается, что антагонизм M1 mAChR является механизмом, с помощью которого Клемастин, развивающийся препарат, который был замечен в целях усиления миелинизации в исследованиях животных и клинических испытаниях этапа II, вызывает его эффект, стимулирующий миелинацию. Недавние исследования

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… Furthermore, considering De Angelis et al (2012) had used muscarine, a general muscarinic agonist that is not selective for a particular mAChR subtype ( Eglen and Watson, 1996 ), it is unclear whether this cross-talk with Notch-1 is mediated specifically by the M1 mAChR subtype. … Apart from clemastine, other nonselective muscarinic antagonists can also stimulate OPC differentiation and remyelination ( Melchor et al, 2019 ). …

Muscarinic control of cardiovascular function in humans: a review of current clinical evidence.

PURPOSE: To review the available evidence on the impact of muscarinic receptor modulation on cardiovascular control in humans. METHODS: In this narrative Review we summarize data on cardiovascular endpoints from clinical trials of novel subtype-selective or quasi-selective muscarinic modulators, mostly PAMs, performed in the last decade. We also review the cardiovascular phenotype in recently described human genetic and autoimmune disorders affecting muscarinic receptors. RESULTS: Recent advancements in the development of compounds that selectively target muscarinic acetylcholine receptors a

Autoantibodies Blocking M3 Muscarinic Receptors Cause Postganglionic Cholinergic Dysautonomia.

A 10-year-old girl presented with ileus, urinary retention, dry mouth, lack of tears, fixed dilated pupils, and diffuse anhidrosis 7 days after a febrile illness. We hypothesized that her syndrome was due to autoimmunity against muscarinic acetylcholine receptors, blocking their activation. Using an indirect enzyme-linked immunosorbent assay for all 5 muscarinic receptors (M1 -M5 ), we identified in the patient's serum antibodies that selectively bound to M3 receptors. In vitro functional studies confirmed that these autoantibodies selectively blocked M3 receptor activation. Thus, autoantibodi

Second M3 muscarinic receptor binding site contributes to bronchoprotection by tiotropium.

BACKGROUND AND PURPOSE: The bronchodilator tiotropium binds not only to its main binding site on the M3 muscarinic receptor but also to an allosteric site. Here, we have investigated the functional relevance of this allosteric binding and the potential contribution of this behaviour to interactions with long-acting β-adrenoceptor agonists, as combination therapy with anticholinergic agents and β-adrenoceptor agonists improves lung function in chronic obstructive pulmonary disease. EXPERIMENTAL APPROACH: ACh, tiotropium, and atropine binding to M3 receptors were modelled using molecular dynami

Pharmacogenetics of tardive dyskinesia in schizophrenia: The role of CHRM1 and CHRM2 muscarinic receptors.

Objectives: Acetylcholine M (muscarinic) receptors are possibly involved in tardive dyskinesia (TD). The authors tried to verify this hypothesis by testing for possible associations between two muscarinic receptor genes (CHRM1 and CHRM2) polymorphisms and TD in patients with schizophrenia.Methods: A total of 472 patients with schizophrenia were recruited. TD was assessed cross-sectionally using the Abnormal Involuntary Movement Scale. Fourteen allelic variants of CHRM1 and CHRM2 were genotyped using Applied Biosystems amplifiers (USA) and the MassARRAY System by Agena Bioscience.Results: The p

[Role and mechanism of muscarinic acetylcholine receptor in the regulation of submandibular gland secretion].

Muscarinic acetylcholine receptors (mAChRs), including M1-M5 subtypes, are classic receptors in regulating water, ion, and solute transport in salivary gland. Our work focuses on the studies on the expression pattern and function of mAChR in the submandibular gland (SMG), and the underlying mechanism involved in the mAChR-regulated secretion, together with the effect of parasympathectomy on the salivary secretion. Microvascular autotransplantation of SMG into the temporal fossa provides a continuous and endogenous source of fluids, and is currently an effective method for treating severe kerat

Expression of muscarinic acetylcholine receptors in hepatocytes from rat fibrotic liver.

The pathological changes of parasympathetic nerve are considered as an independent prognostic factor of the survival rate of patients with chronic liver disease. The non-selective muscarinic acetylcholine receptors (mAchR) agonists and antagonists can affect the proliferation of hepatocytes and hepatic stellate cells, but the subtypes of mAchR expressions in HCs are still uncertain. Here, we investigate the expression of mAchR in hepatic fibrosis on rats. 3ml/kg 40% carbon tetrachloride (CCL4) was given to induce hepatic fibrosis on rats and the hepatocytes were isolated. Compared to the norma

Reduced muscarinic parotid secretion is underlain by impaired NO signaling in diabetic rabbits.

OBJECTIVES: The influence of experimental diabetes (alloxan, 100 mg kg(-1) ) was studied on rabbit parotid gland function. MATERIAL AND METHODS: Carbachol-induced parotid secretion in vivo, and in vitro quantification of inducible nitric oxide synthase (iNOS) mRNA expression, by real-time RT-PCR, and activity of superoxide dismutase (SOD) and total antioxidant capacity (TAC) in commercial colorimetric assays were measured in parotid glands of non-diabetic and diabetic rabbits. RESULTS: Carbachol-induced dose-dependent increase in parotid secretion significantly reduced in diabetic rabbits. F

123I-iododexetimide preferentially binds to the muscarinic receptor subtype M1 in vivo.

UNLABELLED: The muscarinic M1 receptor (M1R) is highly involved in cognition, and selective M1 agonists have procognitive properties. Loss of M1R has been found in postmortem brain tissue for several neuropsychiatric disorders and may be related to symptoms of cognitive dysfunction. (123)I-iododexetimide is used for imaging muscarinic acetylcholine receptors (mAchRs). Considering its high brain uptake and intense binding in M1R-rich brain areas, (123)I-iododexetimide may be an attractive radiopharmaceutical to image M1R. To date, the binding affinity and selectivity of (123)I-iododexetimide fo

Epigenetic modulation of the muscarinic type 3 receptor in salivary epithelial cells.

Muscarinic receptors, particularly the type 3 subtype (M3R), have an important role in exocrine secretion. M3R normally function in HSG cells originated from human submandibular gland ducts, but not in A253 and SGT cells, derived from human submandibular carcinoma and salivary gland adenocarcinoma. However, the underlying mechanism of this suppression has remained elusive. In this study, we examined whether M3R function is suppressed by epigenetic modulation of the receptor. To this end, we investigated the mRNA transcript and protein levels of the M3R using reverse transcriptase-PCR, western