Research advances of M3 receptor: a new target for treating and preventing cardiovascular disease / 药学学报

Cardiovascular disease, with high morbidity and mortality, has been threatening the health of human beings. Therefore, expecting to find a more effective therapeutic method, a plenty of researchers devote themselves to the study of the cardiovascular disease all the time. Since discovered on the heart, M3 receptor of muscarinic acetylcholine receptor (mAchR, M receptor) became a new starting point of the research of the cardiovascular disease. With more and more investigation, many people found that M3 receptor could protect the heart from kinds of cardiovascular disease, which may make it a new hopeful therapeutic point. So, expecting to give support to the reference and encouragement for the study of disease related to M3 receptor in future, this review expounds M3 receptor on the heart from the main following aspects: the effect on the heart, the influence on the cardiovascular disease and the mechanism of M3 receptor involved.

Efectividad y seguridad de la oxibutinina o tolterodina comparado con darifenacina, solifenacina, fesoterodina y placebo para el tratamiento de la incontinencia / Effectiveness and safety of oxybutynin or tolterodine compared to darifenacin, solifenacin, fesoterodine and placebo for the treatment of incontinence

Introducción: Alrededor del 16% al 45% de los adultos tiene síntomas de vejiga hiperactiva, que se manifiestan con urgencia para orinar, aumento en la frecuencia de micciones o incontinencia urinaria de urgencia, o ambos, denominado síndrome de vejiga hiperactiva. Los fármacos anticolinérgicos son los tratamientos más comunes para el tratamiento farmacológico y entre ellos la oxibutinina y la tolterodina. Esta evaluación tecnológica se desarrolló en el marco de la actualización integral del Plan Obligatorio de Salud para el año 2015. Objetivo: evaluar la efectividad y seguridad de la oxibutinina o la tolterodina para la incontinencia urinaria, comparadas con otros medicamentos antimuscarínicos como: solifenacina, darifenacina, fesoterodina para informar la toma de decisiones. Metodología: la evaluación fue realizada de acuerdo al protocolo definido previamente por el grupo desarrollador. Se realizó una búsqueda sistemática en MEDLINE, EMBASE, Cochrane Database of Systematic Reviews, Database of Abstracts of Reviews of Effects y LILACS, sin restricciones de idioma y limitada a revisiones sistemáticas publicadas en los últimos cinco años. Las búsquedas electrónicas fueron hechas entre octubre y noviembre de 2014 y se complementaron mediante búsqueda manual en bola de nieve y una consulta con expertos temáticos. La tamización de referencias se realizó por dos revisores de forma independiente y los desacuerdos fueron resueltos por consenso. La selección de estudios fue realizada mediante la revisión en texto completo de las referencias preseleccionadas, verificando los criterios de elegibilidad. La calidad de los estudios fue valorada con la herramienta AMSTAR. Las características de los estudios fueron extraídas a partir de las publicaciones originales. Se realizó una síntesis narrativa de las estimaciones del efecto para las comparaciones y desenlaces de interés a partir de los estudios de mejor calidad con AMSTAR. Resultados: se seleccionó una revisión sistemática que incluyó un total de 86 ensayos clínicos (31,249 pacientes) con medicamentos muscarínicos incluyendo a la Oxibutinina y la Tolterodina. Se realizaron comparaciones directas entre medicamentos y comparaciones intratecnología (dosis y presentaciones). Cuando se comparó la Tolterodina versus la Oxibutinina, no se encontró diferencia estadisticamente significativa en los desenlaces de calidad de vida, la percepción de cura o mejora y cuantificación de los síntomas. Cuando se comparó solifenacina versus tolterodina, se encontró diferencia estadisticamente significativa en los mismos desenlaces a favor de la solifenacina, e igual se reportó en la comparación fesoterodina versus tolterodina, a favor de la fesoterodina. Respecto a seguridad se comparó tolterodina versus oxibutinina y el retiro por eventos adversos fue más frecuente en el grupo de la oxibutinina RR 0.52 IC95% 0.40 a 0.66. En la comparación de soliferacina versus oxibutinina el retiro por eventos adversos fue más frecuente en el grupo de oxibutinina RR 0.45 IC95% 0.22 a 0.91 y al comparar la fesoterodina versus la tolterodina el retiro por eventos adversos fue más frecuente en el grupo de la fesoterodina RR 1.45 IC95% 1.07 a 1.98. Conclusiones: Efectividad: No se evidenció diferencia en efectividad entre la Oxibutinina y Tolterodina en los desenlaces de calidad de vida y la percepción de cura o mejora. Para la comparación de efectividad entre Oxibutinina versus Darifenacina y Solifenacina, no se reportaron resultados. La Solfenacina y Fesoterodina son más efectivas que la Tolterodina, en los desenlaces de calidad de vida y la percepción de cura o mejora. Seguridad: Tolterodina fue más seguro que la Oxibutinina, respecto al abandono por eventos adversos. La comparación entre Darifenacina versus oxibutinina no reportó resultados. Solifenacina fue más seguro que la oxibutinina, respecto al abandono por eventos adversos. Tolterodina fue más seguro que Fesoterodina, respecto al abandono por eventos adversos y boca seca.(AU)

Botulinum toxin A inhibits salivary secretion of rabbit submandibular gland / 国际口腔科学杂志·英文版

Botulinum toxin A (BTXA) has been used in several clinical trials to treat excessive glandular secretion; however, the precise mechanism of its action on the secretory function of salivary gland has not been fully elucidated. In this study, we aimed to investigate the effect of BTXA on secretion of submandibular gland in rabbits and to identify its mechanism of action on the secretory function of salivary gland. At 12 weeks after injection with 5 units of BTXA, we found a significant decrease in the saliva flow from submandibular glands, while the salivary amylase concentration increased. Morphological analysis revealed reduction in the size of acinar cells with intracellular accumulation of secretory granules that coalesced to form a large ovoid structure. Expression of M3-muscarinic acetylcholine receptor (M3 receptor) and aquaporin-5 (AQP5) mRNA decreased after BTXA treatment, and distribution of AQP5 in the apical membrane was reduced at 1, 2 and 4 weeks after BTXA injection. Furthermore, BTXA injection was found to induce apoptosis of acini. These results indicate that BTXA decreases the fluid secretion of submandibular glands and increases the concentration of amylase in saliva. Decreased expression of M3 receptor and AQP5, inhibition of AQP5 translocation, and cell apoptosis might involve in BTXA-reduced fluid secretion of submandibular glands.

Relaxing Effect of Acetylcholine on Phenylephrine-Induced Contraction of Isolated Rabbit Prostate Strips Is Mediated by Neuronal Nitric Oxide Synthase

PURPOSE: The location of acetylcholinesterase-containing nerve fibers suggests a role for acetylcholine in both contractility and secretion in the prostate gland. The colocalization of nitrergic nerves with cholinergic nerves, and the cotransmission of nitric oxide with acetylcholine in cholinergic nerves, has been demonstrated in the prostate glands of various species. Thus, we investigated the effects of acetylcholine on phenylephrine-induced contraction and the correlation between cholinergic transmission and nitric oxide synthase by using isolated prostate strips of rabbits. MATERIALS AND METHODS: Isolated prostate strips were contracted with phenylephrine and then treated with cumulative concentrations of acetylcholine. Changes in acetylcholine-induced relaxation after preincubation with NG-nitroarginine methyl ester, 7-nitroindazole, and aminoguanidine were measured. The effects of selective muscarinic receptor antagonists were also evaluated. RESULTS: In the longitudinal phenylephrine-contracted strip, the cumulative application of acetylcholine (10(-9) to 10(-4) M) elicited a concentration-dependent relaxation effect. Acetylcholine-induced relaxation was inhibited not only by nitric oxide synthase inhibitors (10 microM L-NAME or 10 microM 7-nitroindazole) but also by 10 microM atropine and some selective muscarinic receptor antagonists (10(-6) M 11-([2-[(diethylamino)methyl]-1-piperdinyl]acetyl)-5,11-dihydro-6H-pyrido[2,3-b][1,4]benzodiazepine-6-one and 10(-6) M 4-diphenylacetoxy-N-methyl-piperidine). In contrast, relaxation was significantly increased by pretreatment of the strips with 10 mM L-arginine. CONCLUSIONS: Acetylcholine relaxed phenylephrine-induced contractions of isolated rabbit prostate strips. This relaxation may be mediated via both cholinergic and constitutive nitric oxide synthase with both the M2 and M3 receptors possibly playing key roles.

Insulinotropic action of hippocampal cholinergic neurostimulating peptide mediated by activated type 3 muscarinic receptor in INS-1 cells / 南方医科大学学报

<p><b>OBJECTIVE</b>[corrected] To characterize the insulinotropic action of hippocampal cholinergic neurostimulating peptide (HCNP) and analyze the role of type 3 muscarinic receptor (M(3)R) pathway in the action of HCNP.</p><p><b>METHODS</b>INS-1 cells were incubated in routine RPMI 1640 medium (control group), RPMI 1640 supplemented with 50 pg/ml synthetic HCNP (HCNP group), or HCNP-containing medium with the addition of PMA 18 h prior to insulin release assay. The insulin levels in the medium was measured using radioimmunoassay following stimulation with different concentrations of glucose. Real-time quantitative PCR was used for detecting the gene expression of HCNP-pp, choline acetyltransferase (ChAT) and M(3)R in HCNP group and control group.</p><p><b>RESULTS</b>After stimulation with different concentrations of glucose (5.6 and 16.7 mmol/L), HCNP group showed significantly higher insulin levels than the control and HCNP+ PMA groups. Compared with those in the control group, the mRNA levels of HCNP-pp, ChAT, and M(3)R were all lowered in HCNP group.</p><p><b>CONCLUSION</b>HCNP can promote insulin release in INS-1 cells by increasing ChAT activity and activating M(3)R, and this effect is inhibited by PMA.</p>

Changes of nerve growth factor and M3 subtype muscarinic receptor in the seminal vesicle of diabetic rats / 中华男科学杂志

<p><b>OBJECTIVE</b>To investigate the effect of diabetic autonomic neuropathy on the seminal vesicle and search for the theoretical evidence for the prevention and treatment of diabetic infertility by observing changes in the contents of the nerve growth factor (NGF) and muscarinic M3 receptor in the seminal vesicle of diabetic rats.</p><p><b>METHODS</b>Diabetic models were established in 10 of the 15 male adult SD rats by intraperitoneal injection of streptozotocin (STZ), and the other 5 were included in a normal control group. Eight weeks after modeling, seminal vesicles were collected from the rats for HE and immunohistochemical staining.</p><p><b>RESULTS</b>Compared with the normal controls, the diabetic models showed a decreased number of smooth muscle cells, thinner cytoplasm of glandular epithelial cells and disordered structure in the seminal vesicle. The intensity of NGF-positive staining was significantly enhanced, but that of M3 markedly reduced in the diabetic group. There were statistically significant differences in the mean integrated optical density (IA) of muscarinic M3 receptors and NGF between the control and diabetic groups (0.0187 +/- 0.0024 vs 0.0100 +/- 0.0015 and 0.0209 +/- 0.0085 vs 0.0412 +/- 0.0117, P<0.01).</p><p><b>CONCLUSION</b>The changes in the expressions of NGF and M3 receptors in the seminal vesicle of diabetic rats suggest that diabetes mellitus may induce autonomic neuropathy of the seminal vesicle.</p>

Expression of M3 subtype of muscarinic receptor during the skin incised wound healing in mice / 法医学杂志

OBJECTIVE@#To investigate the expression of M3 subtype of muscarinic receptors (M3R) during the incised wound healing of the skin in mice and the characteristics of its time-dependent.@*METHODS@#The change of M3R in skin incised wound was detected by immunohistochemical staining and Western blot.@*RESULTS@#M3R-positive cells were detected in epidermis, hair follicle, sebaceous glands, sweat glands, dermomuscular layer in normal mouse skin. Expression of M3R was mainly detectable in polymorphonuclear cells (PMNs) in the wound specimens aged from 6h to 12h after injury. Afterwards, the M3R-positive cells were mostly mononuclear cells (MNCs) and fibroblastic cells (FBCs) at 1 d to 3d post-injury, whereas the M3R-positive cells were mostly FBCs aged from 5 d to 14d. Morphometrically, the ratio of the M3R-positive cells increased aged from 6h to 12h after injury, with a peak at 12h. The ratios kept a high relatively level aged from 1 d to 5 d, but significantly that lowered as compared with aged 12h after injury. The ratio reached the peak at 7 d again after injury, and then decreased gradually. The M3R protein also revealed a time-dependent tendency with double peaks at 12h and 7 d after injury as detected by Western blotting.@*CONCLUSION@#M3R is time-dependently expression in PMNs, MNCs and FBCs suggesting that it may play roles during the skin incised wound healing, and M3R may be used as a marker for wound age determination.

Therapeutic effect of tiotropium bromide powder inhalation in patients with stable bronchiectasis / 南方医科大学学报

<p><b>OBJECTIVE</b>To observe the therapeutic effect of tiotropium bromide powder inhalation on stable bronchiectasis.</p><p><b>METHODS</b>Twenty-two patients with stable bronchiectasis received inhalation of totropium bromide powder at the daily dose of 18 microg, and on days 1 and 28, the patients were examined for forced expiratory volume in one second (FEVl), predicted value [FEVl(%)], forced expiratory volume (FEV), and FEVl/FVC. The symptom score and BODE index were also recorded.</p><p><b>RESULTS</b>After 1 month of inhalation therapy, the FEV1% of the patients showed a moderate increase but the increment was not statistically significant (t=-1.875, P>0.05); the symptom score and BODE index decreased significantly after the therapy (t=7.091, P<0.001; t=2.982, P<0.05).</p><p><b>CONCLUSION</b>Long-term inhalation of tiotropium bromide powder can improve the clinical symptoms and BODE index and enhance the exercise tolerance and quality of life of the patients with bronchiectasis.</p>

Acetylcholine induces hyperpolarization independent of NO-release in guinea pig spiral modiolar artery / 中国应用生理学杂志

<p><b>AIM</b>Acetylcholine(ACh) is a neurotransmitter and a potent vasodilator in many vascular beds. ACh hyperpolarizes the smooth muscle cells(SMCs) of arteries including the cochlear spiral modiolar artery(SMA) via an endothelium-dependent mechanism, but the biochemical and biophysical basis of the hyperpolarization and vasodilation remain unclear and controversial.</p><p><b>METHODS</b>Using intracellular recording techniques and an in vitro preparation of the SMA, the ionic mechanism of the hyperpolarization and a possible role of nitric oxide(NO) were investigated.</p><p><b>RESULTS</b>With 5 mmol/L K(+) in the bathing solution and a minimum longitudinal tension, ACh (0.1-10 micromol/L) induced a robust hyperpolarization in low RP cells but caused a depolarization in the high RP cells. The ACh hyperpolarization was fast in onset and offset and the amplitude was concentration-dependent(22 and 30 mV by 1 micromol/L and 10 micromol/L ACh, respectively, n = 7 ). ACh also hyperpolarized the cells that initially had a high resting potential (RP) but were pre-depolarized by Ba(2+) (50-100 micromol/L). The onset time courses of the hyperpolarization were often slower in these cases than those without the presence of Ba(2+) . The ACh-induced hyperpolarization was blocked by atropine (0.1- 1 micromol/L, n = 6) or DAMP (50 -100 nmol/L, n = 6, a selective M3 antagonist) and also by BAPTA-AM (10 micromol/L, n = 7, a membrane-permeable Ca(2+)-chelator), or charybdotoxin plus apamin (50-100 nmol/L, n= 4, Ca(2+) -activated K(+) -channel blockers), but not by Nomega-nitro-L-arginine methyl ester (L-NAME, 300 micromol/L, n = 8, an inhibitor of NO-synthase), glipizide (10 micromol/L, n = 4, ATP-sensitive K(+) -channel blocker) and indomethacin (10 micromol/L, n = 4, cyclo-oxygenase inhibitor).</p><p><b>CONCLUSION</b>It is concluded that ACh-induced hyperpolarization in the arterial SMCs is primarily due to an activation of calcium-activated potassium channels via M3 receptors of endothelial cell and is independent of NO-release in the spiral modiolar artery.</p>

Expression change of Muscarinic receptor subunits in rat flocculus following unilateral labyrinthectomy / 临床耳鼻咽喉头颈外科杂志

OBJECTIVE@#To observe the expression of Muscarinic receptor M1, M3, M5 subunits in rat flocculus following left unilateral labyrinthectomy (UL).@*METHOD@#The RT-PCR was used to observe the expression of Muscarinic receptor M1, M3, M5 subunits post-unilateral labyrinthectomy and investigate its effect on vestibular compensation.@*RESULT@#Muscarinic receptor M1, M3, M5 subunits were induced decrease in both side flocculus after unilateral labyrinthectomy. The expression was the least in the 1 d flocculus of following UL. The expression is rising from the 3-7 d flocculus of following UL. No difference was observed in the 7 d and sham operation flocculus following UL. No difference was observed in the ipsilateral and contralateral flocculus at any group.@*CONCLUSION@#Muscarinic receptor M1, M3, M5 subunits were induced decrease in the flocculus after unilateral labyrinthectomy. But the significance of the change of Muscarinic receptor M1, M3, M5 subunits in the vestibular compensation is still unknown.

Role of ventricular M3 receptor in arrhythmia resulted from cerebral-cardiac syndrome / 药学学报

To detect the function and expression of ventricular M3 receptor (M3R) in cerebral-cardiac syndrome (CCS) model rats and to explore the relationship between the expression of M3R and the arrhythmia resulted from CCS, CCS model rats were induced by occluding right middle cerebral artery. ECG was monitored. Intracellular calcium ([Ca2+]i) changes after agitating M3R were recorded by laser scanning confocal microscope. Changes of M3R expression in the ventricular tissue were detected by Western blotting. QRS and QT intervals in CCS group were remarkably longer than that in sham group. According to the results of Western blotting, the level of M3R expression was remarkably lower in CCS group compared with that in the normal group. KCl induced [Ca2+]i increasing in CCS group could be depressed by choline and the effect of choline could be blocked by 4-DAMP. The lower expression of M3R in CCS group may be one of important reasons of arrhythmia resulted from CCS. M3R that depressed the [Ca2+]i increasing agitated by choline may become a new target to cure arrhythmia resulted from CCS.

Resveratrol restored the structural and functional association between M3 receptor and connexin 43 gap junction proteins in ischemia-reperfusion injury of isolated rat heart / 药学学报

This study is to explore whether the protective effect of resveratrol on ischemia-reperfusion injury is correlated with the structural and functional association between M3 receptor (M3 subtype of muscarinic acetylcholine receptor) and Cx43 (connexin 43 gap junction proteins). Immunoprecipitation, immunoblotting and immunofluorescence were applied to investigate whether resveratrol has an effect on structural and functional association between M3 and Cx43. The effect of resveratrol on electrocardiogram Lead II ex vivo in rats, SOD (superoxide dismutase) activity and MDA (malondialdehyde) content was also observed in order to evaluate the protective effect of resveratrol on ischemia-reperfusion injury. Resveratrol could restore the structural and functional association between M3 receptor and Cx43 gap junction proteins that was partially destroyed under ischemia-reperfusion injury. The phosphorylation and spatial distribution disturbances in Cx43 expression caused by ischemia-reperfusion injury were also restored. Also, the QRS duration, SOD activity and MDA content were restored. Resveratrol could restore the structural and functional association between M3 receptor and Cx43 gap junction proteins.

Relationship between carbachol hyperstimulation-induced pancreatic acinar cellular injury and trypsinogen or NF-kappaB activation in rats in vitro / 华中科技大学学报（医学）（英德文版）

The relationship between M3 cholinergic receptor agonist (carbachol) hyperstimulation-induced pancreatic acinar cellular injury and trypsinogen activation or NF-kappaB activation in rats was studied in vitro. Rat pancreatic acinar cells were isolated, cultured and treated with carbachol, the active protease inhibitor (pefabloc), and NF-kappaB inhibitor (PDTC) in vitro. Intracellular trypsin activity was measured by using a fluorogenic substrate. The cellular injury was evaluated by measuring the leakage of LDH from pancreatic acinar cells. The results showed that as compared with control group, 10(-3) mol/L carbachol induced a significant increase of the intracellular trypsin activity and the leakage of LDH from pancreatic acinar cells. Pretreatment with 2 mmol/L pefabloc could significantly decrease the activity of trypsin and the leakage of LDH from pancreatic acinar cells (P 0.05). It was concluded that intracellular trypsinogen activation is likely involved in pancreatic acinar cellular injury induced by carbachol hyperstimulation in vitro. NF-kappaB activation may not be involved in pancreatic acinar cellular injury induced by carbachol hyperstimulation in vitro.

Integration between M3 muscarinic acetylcholine receptor and connexin 43 as antiarrhythmic targets in rat ventricular myocardium / 药学学报

<p><b>AIM</b>To optimize the method of investigating structural integration between proteins and study the integration between arrhythmia related proteins in molecular level.</p><p><b>METHODS</b>Immunostaining the normal ventricular myocytes was used to observe the distribution of connexin 43 and muscarinic acetylcholine receptor (mAChR). The five mAChR subtypes were precipitated using immunoprecipitation. Then, SDS-PAGE and Western blotting with the anti-connexin 43 antibody were performed to observe whether they were structurally integrated. Further, different concentrations of detergent were used to observe whether this relationship could be broken.</p><p><b>RESULTS</b>The five subtypes of mAChR existed in the cardiac myocyte of the rat, and all the five mAChR subtypes combined with connexin 43. In the normal rat ventricular myocyte membrane, connexin 43 and M3 receptor are co-located. When adding certain concentration of detergent to the membrane protein, the integration between M3 receptor and connexin 43 was broken, and the phosphorylated form of connexin 43 integrated with M3 receptor.</p><p><b>CONCLUSION</b>The results indicated that the structural integration between mAChR and phosphorylation of connexin 43 existed in rat ventricular myocardium, and this integration could be broken by certain concentration of detergent.</p>

Inhibition of ACh on the delayed rectifier-like potassium current in acutely isolated cerebral cortical neurons of rats / 生理学报

The modulation of ACh on delayed rectifier-like potassium currents (I(K)) was studied in freshly dissociated cerebral cortical neurons using the whole-cell patch-clamp technique. Wistar rats between 10- and 14-day old of both sexes were used. After rats were decapitated, their brains were quickly removed, iced, and then manually cut into 400 mum slices. Slices were then incubated for 0.5 h at 32 degrees C in a buffered artificial cerebrospinal fluid (ACSF) bubbled with 95% O2, 5% CO2. Slices were then removed into buffered ACSF containing protease (0.5 mg/ml) at 32 degrees C. After 30 min of enzyme digestion, tissue was rinsed three times in the buffered saline. Then the enzyme-treated slices were mechanically dissociated with a graded series of fire-polished Pasteur pipettes. The cell suspension was then plated into a 35 mm dish and placed on the stage of a Olympus inverted microscope. For whole-cell recordings of currents, standard voltage-clamp techniques were used. Neurons were held at -80 mV, and the I(K) was evoked by 2 000 ms depolarizing voltage commands to potential between -40 mV and +60 mV in 10 mV steps applied at a frequency of 0.5 Hz. It was found that the inhibitory effect of ACh (0.1, 1, 10, 100 mumol/L) on I(K) was dose-dependent. It was also found that ACh affected the activation process of I(K) significantly, i.e., the activation curve of I(K) was characterized by half-activation potential of (-41.8+/-9.7) mV and a slope factor of (30.7+/-7.2) mV in the cortical neurons and they were changed to (-122.4+/-38.6) mV and (42.4+/-7.0) mV, respectively, after giving ACh (10 mumol/L). Tubocurarine (100 mumol/L) antagonized the inhibitory effect of ACh on I(K), and the drop of currents varied from the control value of (36.5+/-7..8)% to (16.9+/-13.8)% (n=8, P<0.01). 4-DAMP (10 mumol/L) blocked the inhibitory effect of ACh on I(K), and the currents reduced from the control value of (36.5+/-7.8)% to (26.8+/-4.7) % (n=6, P<0.05). Pirenzepin did not antagonize the inhibition of ACh on I(K) (n=7, P>0.05). Chelerythrine (20 mumol/L) blocked the inhibitory effect of ACh on I(K) and the currents reduced from the control value of (36.5+/-7.8)% to (11.7+/-17.3)% (n=6, P<0.05). On the contrary, PDBu (10 mumol/L) strengthened the inhibition of ACh on I(K) and the drop of currents changed from the control value of (36.5+/-7.8)% to (59.2+/-14.0)% (n=5, P<0.05). PDBu abolished the antagonism of chelerythrine on ACh in cortical neurons. It is suggested that the ACh-induced depolarization of neurons in the cortex is attributed to the inhibition of I(K) that is most likely evoked by the activation of nicotinic ACh receptors and muscarinic M3 receptor via protein kinase C (PKC) signal transduction pathway.

M3-R/IK(M3)--a new target of antiarrhythmic agents / 药学学报

<p><b>AIM</b>To investigate the relationship between M3-R/IK(M3) and arrhythmia in order to find a new target for antiarrhythmic agents.</p><p><b>METHODS</b>Using the acute ischemic model of rats and patch-clamp techniques, the effects of the M3 receptor on the occurrence of arrhythmias and its possible mechanisms were studied.</p><p><b>RESULTS</b>In acute ischemic model of rats, the M3 receptor antagonist 4-diphenylacetoxy-N-methylpiperidine-methiodide (4DAMP) increased the occurrence of arrhythmias, and the M3 receptor agonist choline suppressed the onset and the development of arrhythmias (P < 0. 01). No change was observed after treatment with other receptor antagonists (M1, M2, and M4). With patch-clamp techniques, it was found that choline induced K+ current could be inhibited by 4DAMP. Antagonists toward M1, M2, and M4 receptors all failed to alter the current.</p><p><b>CONCLUSION</b>Choline modulates the cellular electrical properties of the heart, probably by activating a K+ current via stimulation of the M3 receptor. M3-R/IK(M3) may act as a new target for antiarrhythmic agents.</p>

M3 Subtype of Muscarinic Receptors Mediate Ca2+ Release from Intracellular Stores in Rat Prostate Neuroendocrine Cells

Our previous studies document the expression of adrenoceptors and purinoceptors in the rat prostate neuroendocrine cells (RPNECs). However, a direct investigation of the receptors for acetylcholine (ACh) is still lacking in the prostate neuroendocrine cells. RPNECs were freshly isolated from the ventral lobes of rat prostate by using collagenase. Effects of ACh and various muscarinic antagonists on the intracellular Ca2+ concentration ([Ca2+]c ) were investigated by using the fura-2 spectrofluorimetry. Single-cell RT-PCR analysis was applied to identify the transcripts for the muscarinic receptor subtypes. ACh (5 micrometer) induced a sharp transient increase in the [Ca2+]c of RPNECs, which was independent of the extracellular Ca2+. In the same RPNECs, high KCl (60 mM), phenylephrine (5micrometer), UTP (P2Y1/2 agonist, 50, micrometer), and alpha, beta-meATP (P2X1/3 agonist, 0.5micrometer) also increased the [Ca2+]c. The ACh-induced [Ca2+]c change (delta[Ca2+]c ) was blocked by atropine or by para-fluorohexahydrosiladifenidol (M3 antagonist, 0.3micrometer), but not by telenzepine (M1 antagonist, 1 micrometer) and himbacine (M2 and M4 antagonist, 1 mircoM). The single-cell RT-PCR demonstrated the selective expression of mRNAs for M3 in RPNECs. In summary, RPNECs express M3 muscarinic receptors that are linked to the release of Ca2+ from intracellular stores. The Ca2+ signals of RPNECs might mediate the parasympathetic regulation of prostate gland.

Clinical features and mutation analysis of a poly-(A)8 tract in M3 cholinergic receptor gene in Chinese HNPCC families / 浙江大学学报·医学版

<p><b>OBJECTIVE</b>To characterize the clinical features of Chinese HNPCC families and to screen the mutations of a poly-(A)8 tract in M3 cholinergic receptor gene in these families.</p><p><b>METHODS</b>The clinical features of 15 Chinese HNPCC families were characterized. Genomic DNAs from 15 probands were prepared. PCR and direct DNA sequencing analysis were employed to examine the mutations of a poly-(A)8 tract in exon 8 of M3 cholinergic receptor gene.</p><p><b>RESULTS</b>Total 55 cancer patients were found in 15 families including 41 cases of colorectal carcinoma with an average of 2.73 colorectal carcinomas developed per family. Thirty out of forty-one (73%) patients were diagnosed before age of 50 years. Proximal colon was involved in 51% of patients, while anus and rectum were 40 %. Synchronous and metachronous multiple colorectal cancers developed in 5 patients (12%). Two thirds of families belonged to Lynch II syndrome, and total 18 extracolonic malignancies in 14 patients were identified. Gastric carcinoma was the most common extracolonic types. In 15 HNPCC probands, no mutation was detected in the poly-(A)8 tract of exon 8 of M3 cholinergic receptor gene.</p><p><b>CONCLUSION</b>M3 cholinergic receptor gene might have little relation with HNPCC in Chinese population. The criteria for Chinese HNPCC are useful and practical in clinical application.</p>

Expression of M3 receptor gene in peripheral blood lymphocytes of workers exposed to dimethoate / 中华劳动卫生职业病杂志

<p><b>OBJECTIVE</b>To study the expression of muscarinic receptor M(3) gene in peripheral blood lymphocytes of workers exposed to organophosphorus pesticides (OPPs) and to explore its role in the adverse effects of OPPs.</p><p><b>METHODS</b>The lymphocytes of peripheral blood from 33 workers exposed to dimethoate and 15 control people were isolated and treated with saline and dimethoate respectively in vitro. RT-PCR technique was used to determine M(3) gene expression. Basal and inducible gene expression levels were measured.</p><p><b>RESULTS</b>There was no significant difference in basal gene expression level between exposed group and control group, while the inducible gene expression level was significantly higher in exposure group (1.92 +/- 1.07) than in control group (1.22 +/- 0.19) and basal level (1.49 +/- 0.45, P < 0.05). No differences in basal and inducible gene expression level were found between male and female people in both exposed and control group. The level of inducible M(3) gene expression increased with the increase in length of exposure time [< 5 a: (1.69 +/- 0.95), 5 - 25 a: (1.91 +/- 1.03), > 25 a: (2.09 +/- 1.25), the latter was significantly different from that of < 5 a (P < 0.05)].</p><p><b>CONCLUSION</b>After long-term exposure to OPPs, the basal M(3) receptor gene expression level in the exposed workers did not show any difference from the control group, but the inducible gene expression level (treated with dimethoate in vitro) was increased and related to the extent of exposure to dimethoate.</p>

Relationship between M3 receptor and myocyte apoptosis induced by acute myocardial infarction / 药学学报

<p><b>AIM</b>To explore the effects of M3 receptor on myocyte apoptosis induced by acute myocardial infarction in rats.</p><p><b>METHODS</b>Rat model was induced by ligation of the anterior branch of the left coronary artery. All animals were divided into four groups: sham-operated group, occlusion group, choline group (10 mg x kg(-1), iv), and 4DAMP (4-diphenylacetoxy-N-methylpiperidine-methiodide) group (0.12 mg x kg(-1), iv). The serum malondialdehyde (MDA) content and superoxide dismutase (SOD) activity were determined. The infarct size areas on the myocardium were identified by TTC staining. The apoptosis in cardiomyocyte was detected by TUNEL assay and apoptosis-related proteins in Bcl-2 and Fas expression were measured by immunohistochemistry assay.</p><p><b>RESULTS</b>M3 receptor agonist choline reduced serum MDA content and increased SOD activity. The myocardial expression of Bcl-2 was increased, whereas the expression of Fas was decreased by choline. However, blockade of M3 receptor by 4DAMP completely inhibited these effects of choline on cardiac myocytes.</p><p><b>CONCLUSION</b>Activation of M3 receptor has protective effect on myocyte apoptosis induced by acute myocardial infarction in rat, and this effect might be related to modulating the expression of some immediateearly genes including Bcl-2 and Fas.</p>