Associations of genetic variants in M3 receptor with blood pressure responses to salt and potassium intake / 西安交通大学学报(医学版)

【Objective】 M3 muscarinic acetylcholine receptor(M3 receptor), encoded by CHRM3 gene, is widely distributed in the cardiovascular system and plays an important role in cardiac regulation. The aim of this study was to assess the association of genetic variants in M3 receptor with blood pressure(BP) responses to controlled dietary sodium and potassium interventions. 【Methods】 A total of 333 subjects from 124 families were recruited from the rural areas of northern China. After a three-day baseline observation, they were sequentially on a seven-day low-salt diet, a seven-day high-salt diet, and a seven-day high-salt diet plus potassium supplementation. Thirteen CHRM3 single nucleotide polymorphisms(SNPs) were selected for analysis. 【Results】 SNP rs10802811 of the CHRM3 was significantly associated with diastolic BP(DBP) and mean arterial pressure(MAP) responses to both low-salt and high-salt diets while SNPs rs6429147, rs373288072, rs114677844 and rs663148 showed significant associations with systolic BP(SBP) and MAP responses to high-salt diet. In addition, SNP rs6692904 was significantly associated with SBP, DBP and MAP responses to high-salt diet with potassium supplementation. 【Conclusion】 Genetic variants in M3 receptor are significantly associated with BP responses to sodium and potassium intervention, suggesting that M3 receptor may be mechanistically involved in BP salt and potassium sensitivity.

Structure-activity relationship of pyrazol-4-yl-pyridine derivatives and identification of a radiofluorinated probe for imaging the muscarinic acetylcholine receptor M4

There is an accumulating body of evidence implicating the muscarinic acetylcholine receptor 4 (M4) in schizophrenia and dementia with Lewy bodies, however, a clinically validated M4 positron emission tomography (PET) radioligand is currently lacking. As such, the aim of this study was to develop a suitable M4 PET ligand that allows the non-invasive visualization of M4 in the brain. Structure-activity relationship studies of pyrazol-4-yl-pyridine derivates led to the discovery of target compound 12 - a subtype-selective positive allosteric modulator (PAM). The radiofluorinated analogue, [18F] 12, was synthesized in 28 ± 10% radiochemical yield, >37 GBq/μmol and an excellent radiochemical purity >99%. Initial in vitro autoradiograms on rodent brain sections were performed in the absence of carbachol and showed moderate specificity as well as a low selectivity of [18F] 12 for the M4-rich striatum. However, in the presence of carbachol, a significant increase in tracer binding was observed in the rat striatum, which was reduced by >60% under blocking conditions, thus indicating that orthosteric ligand interaction is required for efficient binding of [18F] 12 to the allosteric site. Remarkably, however, the presence of carbachol was not required for high specific binding in the non-human primate (NHP) and human striatum, and did not further improve the specificity and selectivity of [18F] 12 in higher species. These results pointed towards significant species-differences and paved the way for a preliminary PET study in NHP, where peak brain uptake of [18F] 12 was found in the putamen and temporal cortex. In conclusion, we report on the identification and preclinical development of the first radiofluorinated M4 PET radioligand with promising attributes. The availability of a clinically validated M4 PET radioligand harbors potential to facilitate drug development and provide a useful diagnostic tool for non-invasive imaging.

Muscarinic acetylcholine receptor M1 mediates prostate cancer cell migration and invasion through hedgehog signaling / 亚洲男科学杂志(英文版)

The autonomic nervous system contributes to prostate cancer proliferation and metastasis. However, the exact molecular mechanism remains unclear. In this study, muscarinic acetylcholine receptor M1 (CHRM1) expression was measured via immunohistochemical analysis in human prostate cancer tissue array slides. PC-3, LNCaP, and A549 cells were treated with pirenzepine or carbachol, and the cell migration and invasion abilities were evaluated. Western blotting and quantitative real-time PCR were performed to measure GLI family zinc finger 1 (GLI1), patched 1 (PTCH1), and sonic hedgehog (SHH) expression levels. High expression of CHRM1 was found in early-stage human prostate cancer tissues. In addition, the selective CHRM1 antagonist pirenzepine inhibited PC-3, LNCaP, and A549 cell migration and invasion, but the agonist carbachol promoted the migration and invasion of these three cell lines. Muscarinic signaling can be relayed by hedgehog signaling. These data show that CHRM1 is involved in the regulation of prostate cancer migration and invasion through the hedgehog signaling pathway.

Muscarinic acetylcholine receptor M1 mediates prostate cancer cell migration and invasion through hedgehog signaling / 亚洲男科学杂志(英文版)

The autonomic nervous system contributes to prostate cancer proliferation and metastasis. However, the exact molecular mechanism remains unclear. In this study, muscarinic acetylcholine receptor M1 (CHRM1) expression was measured via immunohistochemical analysis in human prostate cancer tissue array slides. PC-3, LNCaP, and A549 cells were treated with pirenzepine or carbachol, and the cell migration and invasion abilities were evaluated. Western blotting and quantitative real-time PCR were performed to measure GLI family zinc finger 1 (GLI1), patched 1 (PTCH1), and sonic hedgehog (SHH) expression levels. High expression of CHRM1 was found in early-stage human prostate cancer tissues. In addition, the selective CHRM1 antagonist pirenzepine inhibited PC-3, LNCaP, and A549 cell migration and invasion, but the agonist carbachol promoted the migration and invasion of these three cell lines. Muscarinic signaling can be relayed by hedgehog signaling. These data show that CHRM1 is involved in the regulation of prostate cancer migration and invasion through the hedgehog signaling pathway.

Muscarinic Acetylcholine Receptor Subtype Expression in Type Vestibular Hair Cells of Guinea Pigs / 华中科技大学学报（医学）（英德文版）

Recent studies have demonstrated that five subtypes (M1-M5) of muscarinic acetylcholine receptor (mAChR) are expressed in the vestibular periphery.However,the exact cellular location of the mAChRs is not clear.In this study,we investigated whether there is the expression of M1-M5 muscarinic receptor mRNA in isolated type Ⅱ vestibular hair cells of guinea pig by using single-cell RT-PCR.In vestibular end-organ,cDNA of the expected size was obtained by RT-PCR.Moreover,mRNA was identified by RT-PCR from individually isolated type Ⅱ vestibular hair cells (single-cell RT-PCR).Sequence analysis confirmed that the products were M1-M5 mAChR.These results demonstrated that M1-M5 mAChR was expressed in the type Ⅱ vestibular hair cells of the guinea pig,which lends further support for the role of M1-M5 mAChR as a mediator of efferent cholinergic signalling pathway in vestibular hair cells.

The Specific Ligand Screening for M_2-G_（i1α） Fusion Protein Expressed in Sf9 Cells / 中国医科大学学报

Objective Using M2-Gi1α fusion protein expressed by baculovirus-Sf9 cell system to find the specific ligand for M2 receptor and detect the interaction of the two parts of the fusion protein.Methods The fused M2-Gi1α cDNAs were generated in a two-step PCR and then expressed in Sf9 cells.[3H]QNB and[35S]GTPγS binding experiments were employed to study the function of M2-Gi1α fusion protein.Results The expression level of M2-Gi1α fusion protein was 8.44±0.39 nmol·g-1 protein.The affinity of GDP to the Gi1α part changed under the affection of different ligands.The IC50 value in the appearance of acetylcholine,oxotremorine,arecoline,atropine,fangchinoline,levitimide were 21.35 μmol·L-1,23.86 μmol·L-1,11.91 μmol·L-1,0.13 μmol·L-1,1.05 μmol·L-1,1.75 μmol·L-1,and 2.5 μmol·L-1 when there was no ligand.Conclusion The M2-Gi1α fusion protein expressed in baculovirus-Sf9 cell system has pharmacological specificity for M2 receptor and the efficient coupling function between the two parts.The M2-Gi1αfusion protein is a helpful tool for detecting the new specific ligands of the M2 receptor.

Trypanosoma cruzi infection induces up-regulation of cardiac muscarinic acetylcholine receptors in vivo and in vitro

The pathogenesis of chagasic cardiomyopathy is not completely understood, but it has been correlated with parasympathetic denervation (neurogenic theory) and inflammatory activity (immunogenic theory) that could affect heart muscarinic acetylcholine receptor (mAChR) expression. In order to further understand whether neurogenic and/or immunogenic alterations are related to changes in mAChR expression, we studied two models of Trypanosoma cruzi infection: 1) in 3-week-old male Sprague Dawley rats chronically infected with T. cruzi and 2) isolated primary cardiomyocytes co-cultured with T. cruzi and peripheral blood mononuclear cells (PBMC). Using [³H]-quinuclidinylbenzilate ([³H]-QNB) binding assays, we evaluated mAChR expression in homogenates from selected cardiac regions, PBMC, and cultured cardiomyocytes. We also determined in vitro protein expression and pro-inflammatory cytokine expression in serum and cell culture medium by ELISA. Our results showed that: 1) mAChR were significantly (P < 0.05) up-regulated in right ventricular myocardium (means ± SEM; control: 58.69 ± 5.54, N = 29; Chagas: 72.29 ± 5.79 fmol/mg, N = 34) and PBMC (control: 12.88 ± 2.45, N = 18; Chagas: 20.22 ± 1.82 fmol/mg, N = 19), as well as in cardiomyocyte transmembranes cultured with either PBMC/T. cruzi co-cultures (control: 24.33 ± 3.83; Chagas: 43.62 ± 5.08 fmol/mg, N = 7 for both) or their conditioned medium (control: 37.84 ± 3.84, N = 4; Chagas: 54.38 ± 6.28 fmol/mg, N = 20); 2) [³H]-leucine uptake was increased in cardiomyocytes co-cultured with PBMC/T. cruzi-conditioned medium (Chagas: 21,030 ± 2321; control 10,940 ± 2385 dpm, N = 7 for both; P < 0.05); 3) plasma IL-6 was increased in chagasic rats, IL-1â, was increased in both plasma of chagasic rats and in the culture medium, and TNF-á level was decreased in the culture medium. In conclusion, our results suggest that cytokines are involved in the up-regulation of mAChR in chronic Chagas disease.

Identification of specific drugs for M_5 using m_5AChR-G_ (11?) fusion protein / 中国药理学通报

Aim The m_5AChR-G_ 11? fusion protein was expressed by baculovirus-Sf9 cells system, then using it to identify the specific agonists and antagonists for m_5AChR via detecting the affinity of GDP and m_5AChR-G_ 11?. Methods The m_5AChR-G_ 11? fused cDNAs were generated via a two-step PCR protocol and inserted into pBacPAK9 virus vector. We expressed m_5AChR-G_ 11? fusion protein and m_5AChR protein using baculovirus-Sf9 cell system. [ 3H]QNB and [ 35S]GTP?S binding tests were performed to detect the expressional level of receptor proteins and determine the affinity of GDP and m_5AChR-G_ 11? fusion protein. Results The expression level of m_5AChR-G_ 11? was (47.6?3.2) nmol?g -1 protein. The affinity of GDP to G_ 11? partner changed in the presence of different muscarinic ligands. IC_ 50 values of GDP in the presence of ACh, YM796, Oxotremorine, Methixene, Dextimide and atropine were 128.0, 72.1, 68.5, 16.2, 14.9 and 9.7 ?mol?L -1 respectively, and that in the absence of muscarinic ligand was 20.8 ?mol?L -1. Conclusion The m_5AChR-G_ 11? fusion protein has the pharmacological specificity of M_5 receptor and the efficient coupling interaction of the two partner. Affinity of GDP to ligand bound m_5AChR-G_ 11? fusion protein represents the species of muscarinic ligands. ACh is a full agonist for m_5AChR-G_ 11? fusion protein, YM796 and oxotremorine are partial agonists, while methixene, dextimide and atropine are antagonists.

The effect of three steroidal saponins from Yin-tonic herbal medicince on muscarinic cholinergic receptors of cultured rat myocardiac cells / 中国药理学通报

Aim To observe the effect of three steroidal saponins on the M-cholinoceptor density of cultured rat myocardiac cells. Methods The time course of M-cholinoceptor density was observed and diosgenin (DIO),timosaponin aglycone (ZMS,S-configuration) and XMS,a stereoisomeric compound of ZMS in C-25 methyl group,R-configuration) were added to the culture medium from the 12th day of culture at three final concentration of 10~(-7),10~(-6) and 10~(-5) mol?L~(-1),and the M-cholinoceptor density was measured on the 16th day with radioligand binding assay. Results The density of M-cholinoceptor increased gradually at the beginning of culture,reached a plateau at 4～10 days,and then dropped gradually. On the 16th day of culture,the M-cholinoceptor density was about 60% of the plateau value.The up-regulation effect of ZMS on the density of cultured rat myocardiac cells on the 16 th day was only significant at a final concentration of 10~(-5) mol?L~(-1). On the contrary,XMS was effective even when its final concentration was as low as 10~(-7) mol?L~(-1). DIO showed no effect on the M-cholinoceptor density at any of its three concentration. Conclusion The above results indicate that XMS with lower concentration showed similar effect on the M-cholinoceptor density of cultured mylcardiac cells as that of ZMS with more higher concentration.

The effect of ZDY102 on brain M receptor in dementia model rats / 中国药理学通报

Aim To observe the effect of ZDY102, a C25 stereo-isomer of ZMS, the active component of Zhimu, on brain M receptor density of dementia model animals and the correlation with its effect on learning/memory ability. Methods The rats were randomly divided into five groups: control group, model group, model given orally for 2 months with 3.6 mg?kg -1?d -1 of ZDY102 treatment, model treated with 9.0 mg?kg -1?d -1 of ZDY102, and model treated with 18.0 mg?kg -1?d -1 of ZDY102. Dementia model was produced by single unilateral injection of 4 ?l of normal saline containing 4 ?g of ?-amyloid (25～35) and 1 ?g of ibotenic acid into right basal ganglion region with the aid of a stereotaxic equipment. The brain muscarinic receptor density was analyzed with single-site binding assay using 3H-quinuclidinyl benzilae(QNB). The learning/memory ability was measured by Y-maze performance. Results Two months after model production, the learning and memory ability as well as the density of muscarinic receptor in brain were significantly decreased in model rats compared with those in control rats. Parallel models treated with daily oral administration of ZDY102 for two months improved in learning and memory ability and their muscarinic receptor density was significantly increased when compared with model rats. The correlation coefficient between total M receptor densities and the learning/memory ability was significant when examined with linear regression. Conclusion ZDY102 can significantly improve the learning and memory ability and increase the brain muscarinic receptor density of the model. Since brain muscarinic receptors are closely correlated to learning and memory, up-regulation of M receptor density might play a very important role in the therapeutic effect of ZDY102.