Expression Of M2 Muscarinic Receptors Research Articles

Effects of oxotremorine on convulsions in mice induced by scopolamine and food intake after fasting.

Antimuscarinic administration and food intake cause convulsions in mice and rats after fasting for 48h or less. Increased M1 and M2 muscarinic receptor expression in brain regions during fasting, and reversal of changes by refeeding may contribute to these seizures. Since receptor expression is regulated in response to agonist stimulation, this study investigated effects of nonselective muscarinic receptor agonist oxotremorine on convulsions in fasted animals. Mice deprived of food for 24h were given oxotremorine during (0.1mg/kg, twice daily, s.c.) or after (0.05 or 0.1mg/kg, i.p.) fasting. Fasted animals were treated with saline or scopolamine (i.p.) and observed for 30min for the convulsions after being allowed to eat ad libitum. Oxotremorine administration during fasting produced no significant effect on convulsion development. Incidence and onset of convulsions, and seizure stages were indifferent between the scopolamine and oxotremorine - scopolamine groups. However, oxotremorine (0.1mg/kg) administration after fasting reduced incidence of convulsions. Resulting from an agonist-antagonist interaction at M1 and/or M2 muscarinic receptors, oxotremorine administered after fasting exhibited an anticonvulsant activity. Oxotremorine administration during fasting was expected to suppress seizure development via inhibition of receptor expression. Results did not confirm this expectation and suggested that muscarinic receptor expression was either not affected or not related to the convulsions. Food intake after fasting, and food deprivation have been shown to induce cholinergic hyperexcitability. Although contrary to our hypothesis, future research may investigate whether increased expression of muscarinic receptors mediate or contribute to an increase in cholinergic activity.

Selective Activation of M1 Muscarinic Receptors Attenuates Human Colon Cancer Cell Proliferation.

M3 muscarinic receptor (M3R) activation stimulates colon cancer cell proliferation, migration, and invasion; M3R expression is augmented in colon cancer and ablating M3R expression in mice attenuates colon neoplasia. Several lines of investigation suggest that in contrast to these pro-neoplastic effects of M3R, M1R plays an opposite role, protecting colon epithelial cells against neoplastic transformation. To pursue these intriguing findings, we examined the relative expression of M1R versus M3R in progressive stages of colon neoplasia and the effect of treating colon cancer cells with selective M1R agonists. We detected divergent expression of M1R and M3R in progressive colon neoplasia, from aberrant crypt foci to adenomas, primary colon cancers, and colon cancer metastases. Treating three human colon cancer cell lines with two selective M1R agonists, we found that in contrast to the effects of M3R activation, selective activation of M1R reversibly inhibited cell proliferation. Moreover, these effects were diminished by pre-incubating cells with a selective M1R inhibitor. Mechanistic insights were gained using selective chemical inhibitors of post-muscarinic receptor signaling molecules and immunoblotting to demonstrate M1R-dependent changes in the activation (phosphorylation) of key downstream kinases, EGFR, ERK1/2, and p38 MAPK. We did not detect a role for drug toxicity, cellular senescence, or apoptosis in mediating M1R agonist-induced attenuated cell proliferation. Lastly, adding M1R-selective agonists to colon cancer cells augmented the anti-proliferative effects of conventional chemotherapeutic agents. Collectively, these results suggest that selective M1R agonism for advanced colon cancer, alone or in combination with conventional chemotherapy, is a therapeutic strategy worth exploring.

Role of cholinergic agents in proliferation and caspase activity of hemin-induced erythroid differentiated K562 cells

Background: Muscarinic receptors have many functions in the cells and tissues. Acetylcholine (ACh) plays an important role in cellular physiology. ACh also acts at the different parts of the central nervous system and nonneuronal cells. Cholinergic receptors also have different functions in many cell types and tissues. Caspases (cysteine aspartic proteases and cysteine aspartases) are cysteine dependent aspartate-specific proteases. They are an important role in necrosis and cell death and inflammation signaling pathways. They are also the primary mediators of apoptosis. During apoptosis, different caspase types participate in different functions. We have previously shown that carbachol (CCh) inhibits K562 cell proliferation. This study was performed to investigate the anti-tumor efficacy of cholinergic drugs in hemin-induced erythroid differentiated K562 cells. The aim of this study was to address the mechanism of cholinergic drugs on hemin-induced erythroid differentiated K562 cell proliferation and caspase activities. We detected M3 muscarinic receptor expression in erythroid differentiated K562 cell line.Methods: K562 cells were differentiated with hemin (50 μM). The expression of the M3 muscarinic receptor was detected by the western blotting technique. Erythroid differentiated K562 cells treated with CCh (100 μM). After 24 and 48 h, cells were counted by BrdU cell proliferation kit. Caspase 3,8, and 9 activities were measured by enzyme-linked immunosorbent assay (ELISA) kits according to the manufacturer’s instructions.Results: Erythroid differentiated K562 cell proliferation was not significantly increased after CCh treatment. In the meantime, caspases 8 and 9 activities in erythroid differentiated K562 cell line was significantly higher than undifferentiated K562 cells (p < .05).

M3 muscarinic receptor activation reduces hepatocyte lipid accumulation via CaMKKβ/AMPK pathway

Previously, we reported that hepatic muscarinic receptors modulate both acute and chronic liver injury, however, the role of muscarinic receptors in fatty liver disease is unclear. We observed in patients who underwent weight loss surgery, a decrease in hepatic expression of M3 muscarinic receptors (M3R). We also observed that fat loading of hepatocytes, increased M3R expression. Based on these observations, we tested the hypothesis that M3R regulate hepatocyte lipid accumulation. Incubation of AML12 hepatocytes with 1 mM oleic acid resulted in lipid accumulation that was significantly reduced by co-treatment with a muscarinic agonist (pilocarpine or carbachol), an effect blocked by atropine (a muscarinic antagonist). Similar treatment of Hepa 1–6 cells, a mouse hepatoblastoma cell line, showed comparable results. In both, control and fat-loaded AML12 cells, pilocarpine induced time-dependent AMPKα phosphorylation and significantly up-regulated lipolytic genes (ACOX1, CPT1, and PPARα). Compound C, a selective and reversible AMPK inhibitor, significantly blunted pilocarpine-mediated reduction of lipid accumulation and pilocarpine-mediated up-regulation of lipolytic genes. BAPTA-AM, a calcium chelator, and STO-609, a calcium/calmodulin-dependent protein kinase kinase inhibitor, attenuated agonist-induced AMPKα phosphorylation. Finally, M3R siRNA attenuated agonist-induced AMPKα phosphorylation as well as agonist-mediated reduction of hepatocyte steatosis. In conclusion, this proof-of-concept study demonstrates that M3R has protective effects against hepatocyte lipid accumulation by activating AMPK pathway and is a potential therapeutic target for non-alcoholic fatty liver disease.

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 ...

Evidence for M2 muscarinic receptor modulation of axon terminals and dendrites in the rodent basolateral amygdala: An ultrastructural and electrophysiological analysis

The basolateral amygdala receives a very dense cholinergic innervation from the basal forebrain that is important for memory consolidation. Although behavioral studies have shown that both M1 and M2 muscarinic receptors are critical for these mnemonic functions, there have been very few neuroanatomical and electrophysiological investigations of the localization and function of different types of muscarinic receptors in the amygdala. In the present study we investigated the subcellular localization of M2 muscarinic receptors (M2Rs) in the anterior basolateral nucleus (BLa) of the mouse, including the localization of M2Rs in parvalbumin (PV) immunoreactive interneurons, using double-labeling immunoelectron microscopy. Little if any M2R-immunoreactivity (M2R-ir) was observed in neuronal somata, but the neuropil was densely labeled. Ultrastructural analysis using a pre-embedding immunogold-silver technique (IGS) demonstrated M2R-ir in dendritic shafts, spines, and axon terminals forming asymmetrical (excitatory) or symmetrical (mostly inhibitory) synapses. In addition, about one-quarter of PV+ axon terminals and half of PV+ dendrites, localized using immunoperoxidase, were M2R+ when observed in single thin sections. In all M2R+ neuropilar structures, including those that were PV+, about one-quarter to two-thirds of M2R+ immunoparticles were plasma-membrane-associated, depending on the structure. The expression of M2Rs in PV+ and PV-negative terminals forming symmetrical synapses indicates M2R modulation of inhibitory transmission. Electrophysiological studies in mouse and rat brain slices, including paired recordings from interneurons and pyramidal projection neurons, demonstrated M2R-mediated suppression of GABA release. These findings suggest cell-type-specific functions of M2Rs and shed light on organizing principles of cholinergic modulation in the BLa.

Regulation of molecular clock oscillations and phagocytic activity via muscarinic Ca2+ signaling in human retinal pigment epithelial cells

Vertebrate eyes are known to contain circadian clocks, however, the intracellular mechanisms regulating the retinal clockwork remain largely unknown. To address this, we generated a cell line (hRPE-YC) from human retinal pigmental epithelium, which stably co-expressed reporters for molecular clock oscillations (Bmal1-luciferase) and intracellular Ca2+ concentrations (YC3.6). The hRPE-YC cells demonstrated circadian rhythms in Bmal1 transcription. Also, these cells represented circadian rhythms in Ca2+-spiking frequencies, which were canceled by dominant-negative Bmal1 transfections. The muscarinic agonist carbachol, but not photic stimulation, phase-shifted Bmal1 transcriptional rhythms with a type-1 phase response curve. This is consistent with significant M3 muscarinic receptor expression and little photo-sensor (Cry2 and Opn4) expression in these cells. Moreover, forskolin phase-shifted Bmal1 transcriptional rhythm with a type-0 phase response curve, in accordance with long-lasting CREB phosphorylation levels after forskolin exposure. Interestingly, the hRPE-YC cells demonstrated apparent circadian rhythms in phagocytic activities, which were abolished by carbachol or dominant-negative Bmal1 transfection. Because phagocytosis in RPE cells determines photoreceptor disc shedding, molecular clock oscillations and cytosolic Ca2+ signaling may be the driving forces for disc-shedding rhythms known in various vertebrates. In conclusion, the present study provides a cellular model to understand molecular and intracellular signaling mechanisms underlying human retinal circadian clocks.

Differential expression of M3 muscarinic receptors in progressive colon neoplasia and metastasis.

M3 muscarinic receptor (M3R) activation promotes colon cancer cell proliferation, migration, and invasion in vitro. Although over-expression of CHRM3, the gene encoding M3R, is reported in primary colon cancers, expression of M3R itself has not been studied in colon neoplasia. We compared M3R expression in normal colon to colon adenomas, and primary and metastatic colon cancers. Compared to adjacent normal colon, CHRM3 expression was increased up to 128-fold in 10 of 18 consecutive surgical cancer specimens (56%) and associated with metastatic spread (P < 0.05). To analyze M3R protein expression we interrogated 29 consecutive paraffin-embedded colon adenocarcinomas and adjacent normal colon using a specific anti-M3R antibody and immunoperoxidase staining. This revealed weak M3R expression in normal colonocytes, primarily on basolateral surfaces. In contrast, in 25 of 29 cancer tissues (86%) we observed both cytoplasmic and plasma membrane over-expression of M3R; compared to normal epithelium, mean M3R staining intensity was increased more than two-fold in colon cancer (P < 0.001). M3R staining was also increased in 22 colon adenomas compared to adjacent normal colon (P < 0.001). In contrast, M3R staining intensity was not increased in lymph node or liver metastases. These findings suggest M3R expression plays an important role in early progression and invasion of colon neoplasia but is less important once tumors have spread.

Urothelial Barrier Deficits, Suburothelial Inflammation and Altered Sensory Protein Expression in Detrusor Underactivity

The pathophysiology of detrusor underactivity remains unclear and impaired bladder afferent function is considered one of the important etiologies. We investigated urothelial barrier deficits, suburothelial inflammation and sensory proteins expressed in the bladder mucosa of patients with detrusor underactivity. Bladder mucosa biopsies were performed in 34 patients with videourodynamic proven detrusor underactivity as the study group and in 10 women with stress urinary incontinence as controls. The expression of zona occuldens-1, E-cadherin in the urothelium, tryptase and apoptosis levels in the suburothelium, β3-adrenoceptor, M2 and M3 muscarinic receptors, P2X3 receptor, and inducible and endothelial nitric oxide synthase were compared between study patients and controls. Study patients included 22 women and 12 men with a mean ± SD age of 56.3 ± 19.7 years, of whom 15 had a history of diabetes. Study patients had significantly lower E-cadherin expression, and a higher number of mast cells and apoptotic cells than controls. Additionally, lower expression of M2 and M3 muscarinic receptors, P2X3 receptors and endothelial nitric oxide synthase was detected in study patients but higher expression of β3-adrenoceptor. In study patients a positive correlation was noted between tryptase and apoptosis levels (r= 0.527) and between the expression of M2 muscarinic receptor and P2X3 receptor (r = 0.403). However, β3-adrenoceptor expression negatively correlated with E-cadherin expression (r = -0.490, each p <0.05). Urothelial dysfunction, increased suburothelial inflammation and altered sensory protein expressions in bladder mucosa were prominent in patients with detrusor underactivity. Impaired urothelial signaling and sensory transduction pathways appear to reflect the pathophysiology of detrusor underactivity.

Urothelial Dysfunction, Suburothelial Inflammation and Altered Sensory Protein Expression in Men with Bladder Outlet Obstruction and Various Bladder Dysfunctions: Correlation with Urodynamics

We investigated urothelial integrity, suburothelial inflammation and the expression of sensory proteins in the bladder urothelium of male patients with bladder outlet obstruction and various bladder dysfunctions. We prospectively enrolled 33 men with urodynamically proven bladder outlet obstruction as the study group. Bladder biopsies were obtained from all study patients and 10 control patients. The expression of E-cadherin, zonula occludens-1, tryptase, apoptosis, TRPV (transient receptor potential vanilloid) 1 and 4, β3 adrenoreceptor, M2 and M3 muscarinic receptors, P2X3 receptor, and inducible/epithelial nitric oxide synthase were compared between study and control patients. Study patients had significantly lower expression of E-cadherin, and a higher number of suburothelial mast and apoptotic cells than controls. Additionally, higher expression of P2X3 and M2 muscarinic receptors, and lower expression of M3 muscarinic receptor were detected in study patients. The detrusor underactivity subgroup was characterized by significantly higher expression of β3 adrenoreceptors and lower expression of inducible nitric oxide synthase than in controls. In study patients a significantly positive correlation was noted between voided volume and E-cadherin expression (r = 0.372), volume at first sensation of filling and β3 adrenoreceptor expression (r = 0.386), and detrusor pressure and M2 muscarinic receptor expression (r = 0.496) in the bladder urothelium (each p <0.05). Urothelial dysfunction, suburothelial inflammation, cellular apoptosis and alterations in sensory proteins are prominent in bladder dysfunction secondary to bladder outlet obstruction. Impaired urothelial signaling and sensory transduction pathways appear to reflect the pathophysiology of bladder dysfunction and detrusor underactivity in patients with bladder outlet obstruction.

M3 Muscarinic Receptor Interaction with Phospholipase C β3 Determines Its Signaling Efficiency

Phospholipase Cβ (PLCβ) enzymes are activated by G protein-coupled receptors through receptor-catalyzed guanine nucleotide exchange on Gαβγ heterotrimers containing Gq family G proteins. Here we report evidence for a direct interaction between M3 muscarinic receptor (M3R) and PLCβ3. Both expressed and endogenous M3R interacted with PLCβ in coimmunoprecipitation experiments. Stimulation of M3R with carbachol significantly increased this association. Expression of M3R in CHO cells promoted plasma membrane localization of YFP-PLCβ3. Deletion of the PLCβ3 C terminus or deletion of the PLCβ3 PDZ ligand inhibited coimmunoprecipitation with M3R and M3R-dependent PLCβ3 plasma membrane localization. Purified PLCβ3 bound directly to glutathione S-transferase (GST)-fused M3R intracellular loops 2 and 3 (M3Ri2 and M3Ri3) as well as M3R C terminus (M3R/H8-CT). PLCβ3 binding to M3Ri3 was inhibited when the PDZ ligand was removed. In assays using reconstituted purified components in vitro, M3Ri2, M3Ri3, and M3R/H8-CT potentiated Gαq-dependent but not Gβγ-dependent PLCβ3 activation. Disruption of key residues in M3Ri3N and of the PDZ ligand in PLCβ3 inhibited M3Ri3-mediated potentiation. We propose that the M3 muscarinic receptor maximizes the efficiency of PLCβ3 signaling beyond its canonical role as a guanine nucleotide exchange factor for Gα.

Long-term exposure to muscarinic agonists decreases expression of contractile proteins and responsiveness of rabbit tracheal smooth muscle cells

BackgroundChronic airway diseases, like asthma or COPD, are characterized by excessive acetylcholine release and airway remodeling. The aim of this study was to investigate the long-term effect of muscarinic agonists on the phenotype and proliferation of rabbit tracheal airway smooth muscle cells (ASMCs).MethodsASMCs were serum starved before treatment with muscarinic agonists. Cell phenotype was studied by optical microscopy and indirect immunofluorescence, using smooth muscle α-actin, desmin and SM-Myosin Heavy Chain (SM-MHC) antibodies. [N-methyl-3H]scopolamine binding studies were performed in order to assess M3 muscarinic receptor expression on isolated cell membranes. Contractility studies were performed on isolated ASMCs treated with muscarinic agonists. Proliferation was estimated using methyl-[3H]thymidine incorporation, MTT or cell counting methods. Involvement of PI3K and MAPK signalling pathways was studied by cell incubation with the pathway inhibitors LY294002 and PD98059 respectively.ResultsProlonged culture of ASMCs with acetylcholine, carbachol or FBS, reduced the expression of α-actin, desmin and SM-MHC compared to cells cultured in serum free medium. Treatment of ASMCs with muscarinic agonists for 3-15 days decreased muscarinic receptor expression and their responsiveness to muscarinic stimulation. Acetylcholine and carbachol induced DNA synthesis and increased cell number, of ASMCs that had acquired a contractile phenotype by 7 day serum starvation. This effect was mediated via a PI3K and MAPK dependent mechanism.ConclusionsProlonged exposure of rabbit ASMCs to muscarinic agonists decreases the expression of smooth muscle specific marker proteins, down-regulates muscarinic receptors and decreases ASMC contractile responsiveness. Muscarinic agonists are mitogenic, via the PI3K and MAPK signalling pathways.

Functional and Molecular Changes of the Bladder in Rats with Crushing Injury of Nerve Bundles from Major Pelvic Ganglion to the Bladder: Role of RhoA/Rho Kinase Pathway

Voiding dysfunction is a common complication after radical pelvic surgery. To reduce this complication, nerve-sparing radical pelvic surgery was introduced. However, several patients experienced voiding difficulty despite nerve-sparing radical pelvic surgery. Thus, we investigated the functional and molecular changes of the bladder in rats, which demonstrated voiding dysfunction induced by nerve damage during nerve-sparing radical pelvic surgery. Male rats were used and assigned to normal, sham-operated, and bilateral crushing nerve bundles from major pelvic ganglion (MPG) to bladder group. After one, two, and four-week crushing injury, significantly decreased contractile response and increased connective tissue of the detrusor were observed and these results were reliable findings with voiding difficulty following nerve-sparing radical pelvic surgery. After crushing injury, significantly increased M2 muscarinic receptor expression was observed and this might be regarded as the compensatory response. However, M3 muscarinic receptor expression was not significantly changed. The expression of RhoA, ROCK-α, and ROCK-β was significantly increased after one, two, and four-week crushing injury. From these results, the down-regulation of RhoA/Rho kinase pathway might lead to the decreased bladder contractility after crushing injury of nerve bundles from MPG to the bladder despite of the compensated up-regulation of M2 muscarinic receptor.

Purification, characterization and anticancer activity of a polysaccharide from Panax ginseng

In this study, we purified a homogeneous polysaccharide (PGPW1) from the root of Panax ginseng. Its molecular weight was estimated to be 3.5×105Da by high performance liquid chromatography (HPLC) and Gas chromatography (GC) analysis identified that PGPW1 contained Glc, Gal, Man and Ara in the molar ratio of 3.3:1.2:0.5:1.1. Furthermore the antitumor potential of PGPW1 on human bladder T24 cells was evaluated in vitro by MTT, lactate dehydrogenase (LDH), wound scratch and transwell motility assays. PGPW1 dose-dependently displayed potent anti-proliferation and anti-metastatic activities. Moreover the modulating effect of PGPW1 on the binding of 3H-NMS to M3 muscarinic receptors on the surface of T24 cells was evaluated. In muscarinic receptor binding assay, the attenuated expression of M3 muscarinic receptor on the surface of T24 cells by PGPW1 would contribute to its antitumor functions. All the data indicated the potential of its clinical application for the prevention and treatment of bladder cancer metastasis.

Increase in cardiac M2-muscarinic receptor expression is regulated by GATA binding protein 4 (GATA-4) in streptozotocin-induced diabetic rats

BackgroundAn increase in cardiac M2-muscarinic receptor (M2-mAChR) expression in diabetic rats has been observed, but the molecular mechanism of this increase remains unclear. The transcriptional activity of GATA binding protein 4 (GATA-4) has been documented to regulate the expression of M2-mAChR genes. In this study, we were interested in identifying the role of GATA-4 in the increase in M2-mAChR in diabetic rats and a primary culture of cardiomyocytes. MethodsStreptozotocin-induced diabetic rats (STZ-rats) and high-glucose (D-glucose 30mM, 24h)-treated primary cultures of cardiomyocytes from neonatal rats were used to investigate the role of GATA-4 in the change in M2-mAChR. The protein expression was determined by Western blot analysis. Phlorizin (Na+-glucose co-transport inhibitor), insulin, tiron (radical scavenger), PD98059 (ERK inhibitor) and SB203580 (p38 inhibitor) were used. We also silenced GATA-4 by RNAi to investigate the changes in M2-mAChR expression. ResultsThe cardiac output was reduced in STZ-rats with a higher expression of M2-mAChR or phosphorylated GATA-4 in the heart. These changes were reversed after correction of the blood sugar level. In cardiomyocytes, high glucose treatment also increased M2-mAChR expression and GATA-4 phosphorylation. These changes were reversed by tiron (ROS scavenger) or PD98059 (MEK/ERK inhibitor). However, an increase in M2-mAChR expression was not observed when GATA-4 was silenced by small interfering RNA (siRNA) in cardiomyocytes. ConclusionsWe suggest that hyperglycemia can cause a higher expression of M2-mAChR in cardiomyocytes mainly through ROS to enhance MEK/ERK for phosphorylation of GATA-4.

Immunohistochemical Expression of Muscarinic Receptors in the Urothelium and Suburothelium of Neurogenic and Idiopathic Overactive Human Bladders, and Changes With Botulinum Neurotoxin Administration

To investigate the possible associations of urothelial and suburothelial muscarinic receptors with human bladder pathophysiology we examined the immunohistochemical expression of muscarinic receptors types 1, 2 and 3 in the bladder urothelium and suburothelium of patients with neurogenic or idiopathic detrusor overactivity compared with that in controls. We also examined associations with patient quantified symptoms and the effect of intradetrusor botulinum neurotoxin type A treatment. We obtained bladder biopsies from 36 patients with detrusor overactivity before, and 4 and 16 weeks after treatment with intradetrusor botulinum neurotoxin type A via flexible cystoscopy. Patients with neurogenic detrusor overactivity were injected with 300 U botulinum neurotoxin type A and those with idiopathic detrusor overactivity received 200 U. Control biopsies were taken from 7 patients during investigation for asymptomatic microscopic hematuria. We studied muscarinic receptor immunohistochemical expression using commercial antibodies to muscarinic receptors 1, 2 and 3 with results quantified by image analysis. We noted decreased suburothelial muscarinic receptor immunoreactivity in detrusor overactivity biopsies vs controls, which were significant for muscarinic receptors 1 and 3. After successful botulinum neurotoxin treatment we noted only increased muscarinic receptor 1 and 2 immunoreactivity. Urothelial muscarinic receptor 1 and 3 immunoreactivity was increased after treatment. We identified no substantial urothelial muscarinic receptor 2 immunoreactivity. Receptor levels showed inverse correlations with patient urgency and frequency. Decreased muscarinic receptor levels in the urothelium and suburothelium of patients with detrusor overactivity were largely restored to control levels after successful treatment with botulinum neurotoxin type A. Correlations of receptor levels with patient symptoms further support a role for urothelial and suburothelial muscarinic receptors in detrusor overactivity in humans.

β1- and β2-Adrenergic activations enhance excitatory synaptic transmission in layer V/VI pyramidal neurons of the medial prefrontal cortex of rats

The cardiogenic capacity of embryonic stem (ES) cells has been well-investigated. However, little is known about the development of adrenoceptor (AR) systems during the process of ES cell differentiation, which are critically important in cardiac physiology and pharmacology. In this present study, we investigated the expression profile of adrenoceptor subtypes, β-adrenergic modulation of muscarinic receptors and adrenoceptor-related signaling in cardiomyocytes derived from ES cells (ESCMs).Reverse transcription-polymerase chain reaction revealed that undifferentiated mouse ES cells expressed α1A-, α1B-, α1D- and β2-AR mRNA. However, β1-AR was only expressed after vitamin C induction. The expressions of α1A-, α1D- and β1-ARs increased significantly while α1B- and β2-ARs showed no significant change during the differentiation process. Furthermore, we detected the expression of tyrosine hydroxylase. Both α1-AR and β-AR could activate extracellular responsive kinase in ESCMs. Isoprenaline could inhibit the expression of M2 muscarinic receptor protein. CGP20712A, a β1-AR antagonist, up-regulated the expression of M2 muscarinic receptor while ICI118551, a β2-AR antagonist, showed no effect.These results indicated that functional adrenoceptors and tyrosine hydroxylase, a critical enzyme in catecholamine biosynthesis, were differentially expressed in ESCMs. Adrenoceptor-related signaling pathways and β-adrenergic modulation of muscarinic receptors were established during differentiation.

Increased TGFb signaling in type I diabetic mice is associated with parasympathetic dysfunction of the heart

Diabetic Autonomic Neuropathy (DAN), a severe complication of diabetes, is associated with parasympathetic dysfunction, severe arrhythmias and sudden death. We had shown in cardiac myocytes that TGFb attenuates the negative chronotropic response to Carbamylcholine and decreases the expression of M2 muscarinic receptor and Gai2 (components of the cardiac parasympathetic response). Increased TGFb signaling has been implicated in the end organ damage mechanisms in patients and in type I diabetic animal models. Our hypothesis: the decreased response of the diabetic heart to parasympathetic stimulation might be due to increased TGFb signaling. Here we present a new animal model for DAN. Compared to WT, Akita type I diabetic mice showed a decreased Carbamylcholine‐induced bradycardia and a faster recovery to 80% of initial heart rate. Compared to WT, the diabetic heart showed significant increases in mRNA expression of TGFbRII and PAI‐1 (a target of TGFb signaling). Western blots using hearts lysates showed increased phospho‐Smad2/3 and TGFbRII levels in Akita mice. Together with our previous data that TGFb stimulation attenuates the parasympathetic response in cardiac myocytes, these in vivo results suggest that in type I diabetic mice elevated TGFb signaling is associated with parasympathetic dysfunction of the heart, and that TGFb may be involved in the arrhythmia mechanisms in the diabetic heart.

Ligation of Toll-Like Receptor 3 Differentially Regulates M2 and M3 Muscarinic Receptor Expression and Function in Human Airway Smooth Muscle Cells

Background: Viral infection causes asthma exacerbations and airway hyperreactivity. Toll-like receptor 3 (TLR3) recognizes double-stranded RNA (dsRNA) of viral or synthetic origin in a fashion different from protein kinase R (PKR). The aim of this study was to examine the expression and function of TLR3 in human airway smooth muscle (ASM) cells. Methods: Expression of TLR3 and muscarinic receptor (MR), histamine receptor (HR), and cysteinyl leukotriene receptor (CysLTR) subtypes was analyzed by quantitative real-time PCR, flow cytometry, or Western blotting. It was assessed whether ASM cells respond to polyinosinic-polycytidylic acid (poly I:C), a synthetic analog of dsRNA, with alterations in M2R, M3R, H1R, and CysLT1R expression. The function of these subtypes was evaluated by cholinergic regulation of forskolin-stimulated cyclic AMP accumulation or by mobilization of intracellular calcium upon stimulation. Results: ASM cells expressed TLR3 and PKR, and intracellular TLR3 expression was demonstrated. Poly I:C caused decreased M2R and increased M3R expression, without affecting H1R and CysLT1R expression. Poly I:C-treated cells showed decreased cholinergic inhibition of forskolin-stimulated cyclic AMP accumulation and enhanced calcium flux in response to acetylcholine, but not to histamine and LTD₄. These modulating effects of poly I:C were reversed by chloroquine, but not by 2-aminopurine. Conclusions: The data indicate that poly I:C internalized by ASM cells differentially regulates M2R and M3R expression and function by interacting with TLR3 rather than with PKR, suggesting that these changes may contribute to airway hyperreactivity.

Delayed Goblet Cell Hyperplasia, Acetylcholine Receptor Expression, and Worm Expulsion in SMC-Specific IL-4Rα–Deficient Mice

Interleukin 4 receptor α (IL-4Rα) is essential for effective clearance of gastrointestinal nematode infections. Smooth muscle cells are considered to play a role in the type 2 immune response–driven expulsion of gastrointestinal nematodes. Previous studies have shown in vitro that signal transducer and activator of transcription 6 signaling in response to parasitic nematode infection significantly increases smooth muscle cell contractility. Inhibition of the IL-4Rα pathway inhibits this response. How this response manifests itself in vivo is unknown. In this study, smooth muscle cell IL-4Rα–deficient mice (SM-MHCCreIL-4Rα−/lox) were generated and characterized to uncover any role for IL-4/IL-13 in this non–immune cell type in response to Nippostrongylus brasiliensis infection. IL-4Rα was absent from α-actin–positive smooth muscle cells, while other cell types showed normal IL-4Rα expression, thus demonstrating efficient cell-type–specific deletion of the IL-4Rα gene. N. brasiliensis–infected SM-MHCCreIL-4Rα−/lox mice showed delayed ability to resolve infection with significantly prolonged fecal egg recovery and delayed worm expulsion. The delayed expulsion was related to a delayed intestinal goblet cell hyperplasia, reduced T helper 2 cytokine production in the mesenteric lymph node, and reduced M3 muscarinic receptor expression during infection. Together, these results demonstrate that in vivo IL-4Rα–responsive smooth muscle cells are beneficial for N. brasiliensis expulsion by coordinating T helper 2 cytokine responses, goblet hyperplasia, and acetylcholine responsiveness, which drive smooth muscle cell contractions.