M2 Muscarinic Receptor Subtypes Research Articles

M2 Muscarinic Receptor Stimulation Induces Autophagy in Human Glioblastoma Cancer Stem Cells via mTOR Complex-1 Inhibition.

Although autophagy is a pro-survival process of tumor cells, it can stimulate cell death in particular conditions and when differently regulated by specific signals. We previously demonstrated that the selective stimulation of the M2 muscarinic receptor subtype (mAChR) negatively controls cell proliferation and survival and causes oxidative stress and cytotoxic and genotoxic effects in both GBM cell lines and GBM stem cells (GSCs). In this work, we have evaluated whether autophagy was induced as a downstream mechanism of the observed cytotoxic processes induced by M2 mAChR activation by the orthosteric agonist APE or the dualsteric agonist N8-Iper (N8). To assess the activation of autophagy, we analyzed the expression of LC3B using Western blot analysis and in LC3B-EGFP transfected cell lines. Apoptosis was assessed by measuring the protein expression of Caspases 3 and 9. Our data indicate that activation of M2 mAChR by N8 promotes autophagy in both U251 and GB7 cell lines as suggested by the LC3B-II expression level and analysis of the transfected cells by fluorescence microscopy. Autophagy induction by M2 mAChRs is regulated by the decreased activity of the PI3K/AKT/mTORC1 pathway and upregulated by pAMPK expression. Downstream of autophagy activation, an increase in apoptosis was also observed in both cell lines after treatment with the two M2 agonists. N8 treatment causes autophagy via pAMPK upregulation, followed by apoptosis in both investigated cell lines. In contrast, the absence of autophagy in APE-treated GSC cells seems to indicate that cell death could be triggered by mechanisms alternative to those observed for N8.

M1-selective muscarinic allosteric modulation enhances cognitive flexibility and effective salience in nonhuman primates

Acetylcholine (ACh) in cortical neural circuits mediates how selective attention is sustained in the presence of distractors and how flexible cognition adjusts to changing task demands. The cognitive domains of attention and cognitive flexibility might be differentially supported by the M1 muscarinic acetylcholine receptor (mAChR) subtype. Understanding how M1 mAChR mechanisms support these cognitive subdomains is of highest importance for advancing novel drug treatments for conditions with altered attention and reduced cognitive control including Alzheimer's disease or schizophrenia. Here, we tested this question by assessing how the subtype-selective M1 mAChR positive allosteric modulator (PAM) VU0453595 affects visual search and flexible reward learning in nonhuman primates. We found that allosteric potentiation of M1 mAChRs enhanced flexible learning performance by improving extradimensional set shifting, reducing latent inhibition from previously experienced distractors and reducing response perseveration in the absence of adverse side effects. These procognitive effects occurred in the absence of apparent changes of attentional performance during visual search. In contrast, nonselective ACh modulation using the acetylcholinesterase inhibitor (AChEI) donepezil improved attention during visual search at doses that did not alter cognitive flexibility and that already triggered gastrointestinal cholinergic side effects. These findings illustrate that M1 mAChRpositive allosteric modulation enhances cognitive flexibility without affecting attentional filtering of distraction, consistent with M1 activity boosting the effective salience of relevant over irrelevant objects specifically during learning. These results suggest that M1 PAMs are versatile compounds for enhancing cognitive flexibility in disorders spanning schizophrenia and Alzheimer's diseases.

Notch Signal Mediates the Cross-Interaction between M2 Muscarinic Acetylcholine Receptor and Neuregulin/ErbB Pathway: Effects on Schwann Cell Proliferation.

The cross-talk between axon and glial cells during development and in adulthood is mediated by several molecules. Among them are neurotransmitters and their receptors, which are involved in the control of myelinating and non-myelinating glial cell development and physiology. Our previous studies largely demonstrate the functional expression of cholinergic muscarinic receptors in Schwann cells. In particular, the M2 muscarinic receptor subtype, the most abundant cholinergic receptor expressed in Schwann cells, inhibits cell proliferation downregulating proteins expressed in the immature phenotype and triggers promyelinating differentiation genes. In this study, we analysed the in vitro modulation of the Neuregulin-1 (NRG1)/erbB pathway, mediated by the M2 receptor activation, through the selective agonist arecaidine propargyl ester (APE). M2 agonist treatment significantly downregulates NRG1 and erbB receptors expression, both at transcriptional and protein level, and causes the internalization and intracellular accumulation of the erbB2 receptor. Additionally, starting from our previous results concerning the negative modulation of Notch-active fragment NICD by M2 receptor activation, in this work, we clearly demonstrate that the M2 receptor subtype inhibits erbB2 receptors by Notch-1/NICD downregulation. Our data, together with our previous results, demonstrate the existence of a cross-interaction between the M2 receptor and NRG1/erbB pathway-Notch1 mediated, and that it is responsible for the modulation of Schwann cell proliferation/differentiation.

Analysis of Signal Transduction Pathways Downstream M2 Receptor Activation: Effects on Schwann Cell Migration and Morphology.

Background: Schwann cells (SCs) express cholinergic receptors, suggesting a role of cholinergic signaling in the control of SC proliferation, differentiation and/or myelination. Our previous studies largely demonstrated that the pharmacological activation of the M2 muscarinic receptor subtype caused an inhibition of cell proliferation and promoted the expression of pro-myelinating differentiation genes. In order to elucidate the molecular signaling activated downstream the M2 receptor activation, in the present study we investigated the signal transduction pathways activated by the M2 orthosteric agonist arecaidine propargyl ester (APE) in SCs. Methods: Using Western blot we analyzed some components of the noncanonical pathways involving β1-arrestin and PI3K/AKT/mTORC1 signaling. A wound healing assay was used to evaluate SC migration. Results: Our results demonstrated that M2 receptor activation negatively modulated the PI3K/Akt/mTORC1 axis, possibly through -arrestin downregulation. The involvement of the mTORC1 complex was also supported by the decreased expression of its specific target . Then, we also analyzed the expression of , a negative regulator of myelination that resulted in reduced levels after M2 agonist treatment. The analysis of cell migration and morphology allowed us to demonstrate that M2 receptor activation caused an arrest of SC migration and modified cell morphology probably by the modulation of β1-arrestin/cofilin-1 and PKCα expression, respectively. Conclusions: The data obtained demonstrated that M2 receptor activation in addition to the canonical Gi protein-coupled pathway modulates noncanonical pathways involving the mTORC1 complex and other kinases whose activation may contribute to the inhibition of SC proliferation and migration and address SC differentiation.

Evaluation of the effects of donepezil, memantine and α-lipoic acid combined administration in amnesia rats on impaired cognitive functions in terms of behavioural, apoptotic, cholinergic and glutamatergic systems

Objective: The aim of the study was to evaluate the possible protective effects of alpha-lipoic acid (α-LA), donepezil and memantine combined therapy in the scopolamine-induced amnesia rat model. 
 Objective: The aim of the study was to evaluate the possible protective effect of donepezil, memantine and alpha-lipoic acid (α-LA) combined therapy in the scopolamine-induced amnesia rat model. 
 Methods: In this study, the effect of combined therapy used in the treatment of scopolamine-induced amnesia on behavioural parameters was evaluated using Y-maze and new object recognition (NOR) test. In addition, muscarinic acetylcholine receptor subtype M1, N-methyl-D-aspartate receptor NR2B subunit, brain-derived neurotrophic factor (BDNF) and mitochondrial apoptosis-related proteins [B-cell lymphoma-2 (Bcl-2) / Bcl-2 associated X (Bax) ratio, caspase (casp) -3, and -9] expression levels were evaluated using the western blot method in the frontal cortex and hippocampus regions. 
 Results: The main findings of this study demonstrated that in scopolamine-induced amnesia rats, cognitive dysfunction determined by both the Y-maze and the NOR test were reversed with the combined treatment of memantine, donepezil and α-LA. According to immunoblotting results in both brain regions, scopolamine-induced decreased M1, BDNF, Bcl-2 / Bax ratio and increased NR2B, casp-3 and -9 expression levels were found to be reversed to almost control values with combined treatment. 
 Conclusion: Consistent with the literature, our study results suggest that the positive contribution of α-LA to the combined treatment of donepezil and memantine, which is used in the routine treatment of neurodegenerative diseases, may be a treatment option in the future.
 Results: The main findings of this study demonstrated that in scopolamine-induced amnesia rats, cognitive dysfunction determined by both the Y-maze and the NORT test were reversed with the combined treatment of memantine, donepezil and α-LA. In addition, decreased BDNF, M1, bcl-2/bax ratio and increased NR2B, caspase-3 and caspase-9 expression levels due to scopolamine in both regions were improved with α-LA, donepezil and memantine combined therapy. 
 Conclusion: The results of our study and other study results in the literature suggest that α-LA may be a future treatment option due to its positive contribution to the effects of other drugs used in the routine treatment of neurodegenerative diseases.

Design, Formulation and In Vitro Evaluation of Oxybutynin HCl Floating Matrix Tablets

The goal of this study was to prepare and test a hydrodynamically balanced floating matrix controlled Oxybutynin HCl drug delivery system. The muscarinic acetylcholine receptor subtypes M1, M2, and M3 are competitively antagonized by oxybutynin HCl. It is used to treat urinary and bladder problems. It has a 10-12 h elimination half-life. The effervescence produced by the combination of sodium bicarbonate with hydrochloric acid in the stomach causes the Oxybutynin HCl tablets to float in the stomach. Twelve alternative floating tablet formulations were made utilizing direct compression using hydrophilic polymers like HPMC K4M, K15M, and K100M and hydrophobic polymers such ethyl cellulose in various ratios. The produced formulation was characterized using FTIR and DSC analysis. In terms of general appearance, content consistency, hardness, friability, and buoyancy, the examination found that all formulations meet the specifications of official pharmacopoeias and/or standard reference. Formulation F11, which contained 25% HPMC K100M and 12.5% ethyl cellulose, had the best in vitro drug release up to 99% after 12 hours. The formulations with more than 12.5% NaHCO3 had a floating time of more than 12 hours. In vitro drug release kinetics of improved formulation F11 were discovered to be zero order, with anomalous diffusion coupled with erosion being the drug release mechanism. At the conclusion of 90 days, accelerated stability studies revealed negligible change in physicochemical attributes and drug release profiles, indicating that all the formulations were stable.

First-in-Human Assessment of 11C-LSN3172176, an M1 Muscarinic Acetylcholine Receptor PET Radiotracer.

This was a first-in-human study of the PET radiotracer 11C-LSN3172176 for the muscarinic acetylcholine receptor subtype M1. The objectives of the study were to determine the appropriate kinetic model to quantify binding of the tracer to M1 receptors, and the reliability of the chosen quantification method. Methods: Six healthy subjects completed the test-retest protocol, and 5 healthy subjects completed the baseline-scopolamine blocking protocol. Multiple modeling methods were applied to calculate total distribution volume (VT) and nondisplaceable binding potential (BPND) in various brain regions. The reference region was selected from the blocking study. The occupancy plot was applied to compute receptor occupancy by scopolamine and nondisplaceable distribution volume. Results: Tracer uptake was highest in the striatum, followed by neocortical regions and white matter, and lowest in the cerebellum. Regional time-activity curves were fitted well by all models. The 2-tissue-compartment (2TC) model fits were good, but the 2TC parameters often could not be reliably estimated. Because VT correlated well between the 2TC and 1-tissue-compartment (1TC) models after exclusion of unreliable estimates, the 1TC model was chosen as the most appropriate. The cerebellum showed the lowest VT, consistent with preclinical studies showing little to no specific binding in the region. Further, cerebellar VT did not change between baseline and blocking scans, indicating that the cerebellum is a suitable reference region. The simplified reference tissue model (SRTM) slightly underestimated 1TC BPND, and the simplified reference tissue model 2 (SRTM2) improved BPND estimation. An 80-min scan was sufficient to quantify VT and BPND The test-retest study showed excellent absolute test-retest variability for 1TC VT (≤5%) and BPND (≤10%). In the baseline and blocking studies, occupancy values were lower in the striatum than in nonstriatal regions, as may be attributed to differences in regional acetylcholine concentrations. Conclusion: The 1TC and SRTM2 models are appropriate for quantitative analysis of 11C-LSN3172176 imaging data. 11C-LSN3172176 displayed excellent test-retest reproducibility and is a highly promising ligand to quantify M1 receptors in the human brain.

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.

Orthosteric muscarinic receptor activation by the insect repellent IR3535 opens new prospects in insecticide-based vector control

The insect repellent IR3535 is one of the important alternative in the fight against mosquito-borne disease such as malaria, dengue, chikungunya, yellow fever and Zika. Using a multidisciplinary approach, we propose the development of an innovative insecticide-based vector control strategy using an unexplored property of IR3535. We have demonstrated that in insect neurosecretory cells, very low concentration of IR3535 induces intracellular calcium rise through cellular mechanisms involving orthosteric/allosteric sites of the M1-muscarinic receptor subtype, G protein βγ subunits, background potassium channel inhibition generating depolarization, which induces voltage-gated calcium channel activation. The resulting internal calcium concentration elevation increases nicotinic receptor sensitivity to the neonicotinoid insecticide thiacloprid. The synergistic interaction between IR3535 and thiacloprid contributes to significantly increase the efficacy of the treatment while reducing concentrations. In this context, IR3535, used as a synergistic agent, seems to promise a new approach in the optimization of the integrated vector management for vector control.

Effects mediated by M2 muscarinic orthosteric agonist on cell growth in human neuroblastoma cell lines

Abstract The role of muscarinic receptors has been largely documented over the past few decades. Recently we demonstrated that the activation of M2 muscarinic receptors arrested cell proliferation and induced apoptosis in glioblastoma and in other tumour types. This paper aims to evaluate the expression of the M2 muscarinic receptor subtypes in different neuroblastoma cell lines and its role in the control of cell proliferation and survival. Neuroblastoma is the most common solid extracranial tumour, appearing during childhood and displaying a differentiated clinical behaviour. Considering the high homology between muscarinic receptor subtypes, we have identified Arecaidine Propargyl Ester (APE) as a selective orthosteric agonist for M2 muscarinic receptors. Using this agonist, we demonstrate how a selective activation of the M2 receptor subtype negatively modulates cell growth without affecting cell survival in different human neuroblastoma cell lines. As similarly demonstrated in other cell types, following the M2 receptor silencing by short-interference RNA, the effects of APE are completely abolished. We conclude by confirming the ability of APE to bind selectively M2 muscarinic receptor subtypes. Moreover, for the first time we demonstrate that M2 receptor activation inhibits cell growth also in human neuroblastoma cells, indicating that M2 receptors may be an interesting therapeutic target in several solid tumours.

The M1 muscarinic acetylcholine receptor subtype is important for retinal neuron survival in aging mice

Muscarinic acetylcholine receptors have been implicated as potential neuroprotective targets for glaucoma. We tested the hypothesis that the lack of a single muscarinic receptor subtype leads to age-dependent neuron reduction in the retinal ganglion cell layer. Mice with targeted disruption of single muscarinic acetylcholine receptor subtype genes (M1 to M5) and wild-type controls were examined at two age categories, 5 and 15 months, respectively. We found no differences in intraocular pressure between individual mouse groups. Remarkably, in 15-month-old mice devoid of the M1 receptor, neuron number in the retinal ganglion cell layer and axon number in the optic nerve were markedly reduced. Moreover, mRNA expression for the prooxidative enzyme, NOX2, was increased, while mRNA expression for the antioxidative enzymes, SOD1, GPx1 and HO-1, was reduced in aged M1 receptor-deficient mice compared to age-matched wild-type mice. In line with these findings, the reactive oxygen species level was also elevated in the retinal ganglion cell layer of aged M1 receptor-deficient mice. In conclusion, M1 receptor deficiency results in retinal ganglion cell loss in aged mice via involvement of oxidative stress. Based on these findings, activation of M1 receptor signaling may become therapeutically useful to promote retinal ganglion cell survival.

Efficacy and Safety Profile of Extended Release Tolterodine in Symptomatic Overactive Bladder

Background: Overactive Bladder (OAB) is a debilitating medical condition having the symptoms of urinary frequency and urgency with or without urge incontinence. Tolterodine was the first drug developed specifically for the treatment of OAB. It is a competitive muscarinic antagonist that exhibits similar affinities for muscarinic receptor subtypes M1 to M3. Tolterodine may be a more target specific drug that possesses stronger selectivity for the urinary bladder than for the salivary glands. In a pilot study in healthy volunteers, tolterodine was well-tolerated and showed greater function than on salivation.
 Objectives: To study the efficacy of tolterodine (ER) in relieving symptoms of overactive bladder with its adverse effects to determine the safety of the drug.
 Methods: This study was conducted at the Department of Urology, Chittagong Medical College Hospital, Chittagong, Bangladesh, from March, 2014 to June, 2015. Purposive sampling was done. Bladder diary was used for evaluating the symptoms of the patient during baseline and 08 weeks follow up. Perceived level of benefit of the patients was assessed and graded using Likert scale. Data analysis was conducted by SPSS version-21.
 Results: Out of 80 patients, 19 (23.75%) were male and 62 (76.25%) were female with a male: female ratio 1:3.2. The study revealed that the most of the patients, 48 (60.0%) were subjected to much benefit followed by 23 (28.75%) patients experienced little benefit and 09 (11.25%) patients with no benefit from the treatment.
 Conclusion: With mild form of side effects tolterodine showed a significant level of efficacy on overactive bladder.
 Chatt Maa Shi Hosp Med Coll J; Vol.17 (1); Jan 2018; Page 34-37

Acetylcholine Neurotransmitter Receptor Densities in the Striatum of Hemiparkinsonian Rats Following Botulinum Neurotoxin-A Injection.

Cholinergic neurotransmission has a pivotal function in the caudate-putamen, and is highly associated with the pathophysiology of Parkinson's disease. Here, we investigated long-term changes in the densities of the muscarinic receptor subtypes M1, M2, M3 (mAchRs) and the nicotinic receptor subtype α4β2 (nAchRs) in the striatum of the 6-OHDA-induced hemiparkinsonian (hemi-PD) rat model using quantitative in vitro receptor autoradiography. Hemi-PD rats exhibited an ipsilateral decrease in striatal mAchR densities between 6 and 16%. Moreover, a massive and constant decrease in striatal nAchR density by 57% was found. A second goal of the study was to disclose receptor-related mechanisms for the positive motor effect of intrastriatally injected Botulinum neurotoxin-A (BoNT-A) in hemi-PD rats in the apomorphine rotation test. Therefore, the effect of intrastriatally injected BoNT-A in control and hemi-PD rats on mAchR and nAchR densities was analyzed and compared to control animals or vehicle-injected hemi-PD rats. BoNT-A administration slightly reduced interhemispheric differences of mAchR and nAchR densities in hemi-PD rats. Importantly, the BoNT-A effect on striatal nAchRs significantly correlated with behavioral testing after apomorphine application. This study gives novel insights of 6-OHDA-induced effects on striatal mAchR and nAchR densities, and partly explains the therapeutic effect of BoNT-A in hemi-PD rats on a cellular level.

M3-subtype muscarinic receptor activation stimulates intracellular calcium oscillations and aldosterone production in human adrenocortical HAC15 cells.

A previous body of work in bovine and rodent models shows that cholinergic agonists modulate the secretion of steroid hormones from the adrenal cortex. In this study we used live-cell Ca2+ imaging to investigate cholinergic activity in the HAC15 human adrenocortical carcinoma cell line. The cholinergic agonists carbachol and acetylcholine triggered heterogeneous Ca2+ oscillations that were strongly inhibited by antagonists with high affinity for the M3 muscarinic receptor subtype, while preferential block of M1 or M2 receptors was less effective. Acute exposure to carbachol and acetylcholine modestly elevated aldosterone secretion in HAC15 cells, and this effect was also diminished by M3 inhibition. HAC15 cells expressed relatively high levels of mRNA for M3 and M2 receptors, while M1 and M5 mRNA were much lower. In conclusion, our data extend previous findings in non-human systems to implicate the M3 receptor as the dominant muscarinic receptor in the human adrenal cortex.

Stimulation of Acetylcholine Release and Pharmacological Potentiation of Cholinergic Transmission Affect Cholinergic Receptor Expression Differently during Visual Conditioning

Cholinergic stimulation coupled with visual conditioning enhances the visual acuity and cortical responses in the primary visual cortex. To determine which cholinergic receptors are involved in these processes, qRT-PCR was used. Two modes of cholinergic enhancement were tested: a phasic increase of acetylcholine release by an electrical stimulation of the basal forebrain cholinergic nucleus projecting to the visual cortex, or a tonic pharmacological potentiation of the cholinergic transmission by the acetylcholine esterase inhibitor, donepezil. A daily visual exposure to sine-wave gratings (training) was paired with the cholinergic enhancement, up to 14 days. qRT-PCR was performed at rest, 10 min, one week or two weeks of visual/cholinergic training with samples of the visual and somatosensory cortices, and the BF for determining mRNA expression of muscarinic receptor subtypes (m1, m2, m3, m4, m5), nicotinic receptor subunits (α3, α4, α7, β2, β4), and NMDA receptors, GAD65 and ChAT, as indexes of cortical plasticity. A Kruskal–Wallis test showed a modulation of the expression in the visual cortex of m2, m3, m4, m5, α7, β4, NMDA and GAD65, but only β4 within the basal forebrain and none of these mRNA within the somatosensory cortex. The two modes of cholinergic enhancement induced different effects on mRNA expression, related to the number of visual conditioning sessions and receptor specificity. This study suggests that the combination of cholinergic enhancement and visual conditioning is specific to the visual cortex and varies between phasic or tonic manipulation of acetylcholine levels.

MP58-15 M2 AND M3 MUSCARINIC RECEPTOR EXPRESSION IN BLADDER TUMOR

You have accessJournal of UrologyBladder Cancer: Basic Research & Pathophysiology II1 Apr 2018MP58-15 M2 AND M3 MUSCARINIC RECEPTOR EXPRESSION IN BLADDER TUMOR Mehmet Kazim Asutay, Banu Aydin, Hasan Toper, Deniz Filinte, Hülya Cabadak, and Ilker Tinay Mehmet Kazim AsutayMehmet Kazim Asutay More articles by this author , Banu AydinBanu Aydin More articles by this author , Hasan ToperHasan Toper More articles by this author , Deniz FilinteDeniz Filinte More articles by this author , Hülya CabadakHülya Cabadak More articles by this author , and Ilker TinayIlker Tinay More articles by this author View All Author Informationhttps://doi.org/10.1016/j.juro.2018.02.1847AboutPDF ToolsAdd to favoritesDownload CitationsTrack CitationsPermissionsReprints ShareFacebookTwitterLinked InEmail INTRODUCTION AND OBJECTIVES Bladder cancer is one of the most common urogenital cancers of Western society. Transitional cell carcinoma is a heterogeneous cancer type, which costitudes 90% of all bladder cancers. Urothelial cells are continuously in relation with several signal molecules and neurotransmitters. One of these, muscarinic acetyl choline receptors, are expressed on both urothelial cells and detrusor muscle and play a great role in human bladder physiology. Specifically M2 and M3 type receptors are the most common receptors of bladder. M2 receptors are specially found on umbrella cells on the mucosa layer of bladder and almost up to three times more frequent than M3 receptors. Some of the recent studies show the importance and role of muscarinic receptors on some types of disease. In this study muscarinic receptor expression, namely M2 and M3 subtypes of muscarinic receptors were analyzed on bladder tumor samples. METHODS In order to have a strong evidence of M2 and M3 subtypes in bladder tumors, the samples were analyzed both with Western blot technique and with immunohistochemistry. Bladder tumor samples, which are collected by transurethral resection of the bladder, are homogenized, centrifuged and preserved at -80?C. Protein component was analyzed via Lowry method. p< 0.05 data were accepted as statistically significant. The samples also were analyzed by pathologists with immunohistochemistry technique for M2 and M3 muscarinic receptor expression. RESULTS Data of 45 patients were analyzed. Statistical analyses show that patients with pathological T2 stage and with progressed disease during follow-up have greater M2 receptor value which is statistically significant. There was no relation between M3 muscarinic receptor level and tumor grade/stage or progression rate. These results were not dependent by patient age or lower urinary tract symptoms. Progression rate was found higher in patients with higher M2 muscarinic receptor levels on bladder tissue samples. CONCLUSIONS M2 and M3 muscarinic receptors not only play a great role on bladder functions but also also may be important for bladder cancer pathophysiology though, their role in the development of blader cancer has not been defined yet. This current trial may indicate M2 receptors to be a potential treatment target for bladder cancer. © 2018FiguresReferencesRelatedDetails Volume 199Issue 4SApril 2018Page: e778 Advertisement Copyright & Permissions© 2018MetricsAuthor Information Mehmet Kazim Asutay More articles by this author Banu Aydin More articles by this author Hasan Toper More articles by this author Deniz Filinte More articles by this author Hülya Cabadak More articles by this author Ilker Tinay More articles by this author Expand All Advertisement Advertisement PDF downloadLoading ...

Synergistic regulation mechanism of iperoxo and LY2119620 for muscarinic acetylcholine M2 receptor.

Muscarinic acetylcholine receptors are GPCRs that regulate the activity of a diverse array of central and peripheral functions in the human body, including the parasympathetic actions of acetylcholine. The M2 muscarinic receptor subtype plays a key role in modulating cardiac function and many important central processes. The orthosteric agonist and allosteric modulator can bind the pocket of M2. However, the detailed relationship between orthosteric agonist and allosteric modulator of M2 is still unclear. In this study, we intend to elucidate the residue-level regulation mechanism and pathway via a combined approach of dynamical correlation network and molecular dynamics simulation. Specifically computational residue-level fluctuation correlation data was analyzed to reveal detailed dynamics signatures in the regulation process. A hypothesis of “synergistic regulation” is proposed to reveal the cooperation affection between the orthosteric agonist and allosteric modulator, which is subsequently validated by perturbation and mutation analyses. Two possible synergistic regulation pathways of 2CU-I178-Y403-W400-F396-L114-Y440-Nb9 and IXO-V111-F396-L114-Y440-Nb9 were identified by the shortest path algorithm and were confirmed by the mutation of junction node. Furthermore, the efficiency of information transfer of bound M2 is significant higher than any single binding system. Our study shows that targeting the synergistic regulation pathways may better regulate the calcium channel of M2. The knowledge gained in this study may help develop drugs for diseases of the central nervous system and metabolic disorders.

Contribution of M1 and M2 muscarinic receptor subtypes to convulsions in fasted mice treated with scopolamine and given food

Treatment of fasted mice and rats with the nonselective muscarinic antagonist, scopolamine or atropine, causes convulsions after food intake. This study evaluated the effect of fasting on the expression of M1 and M2 muscarinic receptors in the brain regions, the relationship between receptor expression and seizure stages, and the muscarinic receptor subtype which plays a role in the occurrence of convulsions. Mice were grouped as allowed to eat ad lib (fed) and deprived of food for 24h (fasted). Fasted animals developed convulsions after being treated with scopolamine (60%) or the selective M1 receptor antagonist pirenzepine (10mg/kg; 20% and 60mg/kg; 70%) and given food. Fasting increased expression of M1 receptors in the frontal cortex and M2 receptors in the hippocampus, but produced no change in the expression of both receptors in the amygdaloid complex. Food intake after fasting decreased M1 receptor expression in the frontal cortex and M1 and M2 receptor expression in the hippocampus. Seizure severity was uncorrelated with muscarinic receptor expression in the brain regions. Taken together, these findings provide evidence for the role of M1 muscarinic receptor antagonism and fasting-induced increases in M1 and M2 expression possible underlying mechanism in the occurrence of convulsions in fasted animals.

Cognitive enhancement and antipsychotic-like activity following repeated dosing with the selective M4 PAM VU0467154

Although selective activation of the M1 muscarinic acetylcholine receptor (mAChR) subtype has been shown to improve cognitive function in animal models of neuropsychiatric disorders, recent evidence suggests that enhancing M4 mAChR function can also improve memory performance. Positive allosteric modulators (PAMs) targeting the M4 mAChR subtype have shown therapeutic potential for the treatment of multiple symptoms observed in schizophrenia, including positive and cognitive symptoms when assessed in acute preclinical dosing paradigms. Since the cholinergic system has been implicated in multiple stages of learning and memory, we evaluated the effects of repeated dosing with the highly selective M4 PAM VU0467154 on either acquisition and/or consolidation of learning and memory when dosed alone or after pharmacologic challenge with the N-methyl-d-aspartate subtype of glutamate receptors (NMDAR) antagonist MK-801. MK-801 challenge represents a well-documented preclinical model of NMDAR hypofunction that is thought to underlie some of the positive and cognitive symptoms observed in schizophrenia. In wildtype mice, 10-day, once-daily dosing of VU0467154 either prior to, or immediately after daily testing enhanced the rate of learning in a touchscreen visual pairwise discrimination task; these effects were absent in M4 mAChR knockout mice. Following a similar 10-day, once-daily dosing regimen of VU0467154, we also observed 1) improved acquisition of memory in a cue-mediated conditioned freezing paradigm, 2) attenuation of MK-801-induced disruptions in the acquisition of memory in a context-mediated conditioned freezing paradigm and 3) reversal of MK-801-induced hyperlocomotion. Comparable efficacy and plasma and brain concentrations of VU0467154 were observed after repeated dosing as those previously reported with an acute, single dose administration of this M4 PAM. Together, these studies are the first to demonstrate that cognitive enhancing and antipsychotic-like activity are not subject to the development of tolerance following repeated dosing with a selective M4 PAM in mice and further suggest that activation of M4 mAChRs may modulate both acquisition and consolidation of memory functions.

PREPARATION AND CHARACTERIZATION OF TOLTERODINE TARTRATE PRONIOSOMES

Objective: Proniosomes are dry free flowing, granular products that are water soluble carrier particles, coated with surfactants and can be hydrated to form niosomal dispersion immediately before use in hot aqueous media. Tolterodine, is medication used to treat frequent urination, urinary incontinence, or urinary urgency. It acts on M2 and M3 subtypes of muscarinic receptors. Methods: Tolterodine tartrate proniosome formulations were prepared by coacervation phase separation method by using different surfactants in different ratios. The prepared proniosomal formulations were evaluated for vesicle size, rate of spontaneity, encapsulation efficiency, drug content, In vitro release study and stability studies. Results: The size range was found to be 15.28±0.33 to 16.43±0.22 µm. Viscosity of all formulations lies in the range of 7244-9314 cp. Maximum release was shown by formulations of batch PG4 (87.45 %), and minimum for formulations of batch PG4 (50%), after 12 h. Optimized formulations PG4 shows stability at different temperatures. Conclusion: Tolterodine tartrate proniosome formulations prepared by using coacervation phase separation method are capable of releasing drug for the extended period of time. Peer Review History: Received 2 April 2017; Revised 5 May; Accepted 10 May, Available online 15 May 2017 Academic Editor: Dr. DANIYAN Oluwatoyin Michael, Obafemi Awolowo University, ILE-IFE, Nigeria, toyinpharm@gmail.com UJPR follows the most transparent and toughest ‘Advanced OPEN peer review’ system. The identity of the authors and, reviewers will be known to each other. This transparent process will help to eradicate any possible malicious/purposeful interference by any person (publishing staff, reviewer, editor, author, etc) during peer review. As a result of this unique system, all reviewers will get their due recognition and respect, once their names are published in the papers. We expect that, by publishing peer review reports with published papers, will be helpful to many authors for drafting their article according to the specifications. Auhors will remove any error of their article and they will improve their article(s) according to the previous reports displayed with published article(s). The main purpose of it is ‘to improve the quality of a candidate manuscript’. Our reviewers check the ‘strength and weakness of a manuscript honestly’. There will increase in the perfection, and transparency. Received file: Reviewer's Comments: Average Peer review marks at initial stage: 3.0/10 Average Peer review marks at publication stage: 7.0/10 Reviewer(s) detail: Dr. Mohammed Abdel-Wahab Sayed Abourehab, Umm Al-Qura University; Makkah Al-Mukarramah, Saudi Arabia, mohawahab2002@yahoo.com Dr. Sally A. El-Zahaby, Pharos University in Alexandria, Egypt, sally.elzahaby@yahoo.com Similar Articles: INVESTIGATION OF PRONIOSOMES GEL AS A PROMISING CARRIER FOR TRANSDERMAL DELIVERY OF GLIMEPIRIDE FORMULATION AND EVALUATION OF ETODOLAC NIOSOMES BY MODIFIED ETHER INJECTION TECHNIQUE