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1.
Public Health ; 191: 33-38, 2021 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-33482625

RESUMO

OBJECTIVE: The aim of the study was to estimate the gout burden and risk factors in China from 1990 to 2017. STUDY DESIGN: The Global Burden of Disease (GBD) Study uses various analytical tools and a diverse set of data sources to generate comparable estimates of deaths and mortality rates broken down by age, sex, cause, year, and geography. METHODS: We used the results from the GBD Study 2017 to compare disability-adjusted life years (DALYs), prevalence, incidence, and risk factors of gout in China. The median of the percentage change and 95% uncertainty intervals were determined for the period between 1990 and 2017. RESULTS: The age-standardized DALY rate, prevalence, and incidence increased 6.92%, 6.88%, and 6.16%, respectively, in China from 1990 to 2017. Although the rates of gout both globally and in China were increasing, the range of change for males in China was larger than that of the global level. All risk factors combined accounted for 30.04% of gout DALYs in 2017. The leading risk factors for gout DALYs were high body mass index and impaired kidney function, and the proportion of high body mass index increased significantly from 10.67% to 24.31%, whereas the proportion of impaired kidney function remained basically unchanged. CONCLUSIONS: The age-standardized DALY rate, prevalence, and incidence in China have increased progressively since 1990. Increasing attention on body weight management should be prioritized for controlling the rising prevalence of gout in the young and middle-aged population.


Assuntos
Carga Global da Doença/estatística & dados numéricos , Gota/epidemiologia , Adulto , Idoso , Idoso de 80 Anos ou mais , Índice de Massa Corporal , China , Pessoas com Deficiência , Feminino , Humanos , Incidência , Masculino , Pessoa de Meia-Idade , Prevalência , Anos de Vida Ajustados por Qualidade de Vida , Fatores de Risco
2.
Zhonghua Liu Xing Bing Xue Za Zhi ; 43(12): 1939-1944, 2022 Dec 10.
Artigo em Zh | MEDLINE | ID: mdl-36572467

RESUMO

Objective: To explore sex and rural-urban differences in the associations of different blood pressure levels with the risk of prediabetes. Methods: We used a multi-stage stratified cluster random sampling method to investigate 21 637 residents aged ≥18 years from 10 survey areas in Hubei province in 2020. The data on questionnaire, physical measurements, and laboratory indicators of the participants were collected. The associations of different blood pressure levels with risk of prediabetes by sex and regions were analyzed using multivariate logistic regressions after complex weighting. Results: A total of 16 111 subjects were included. The prevalence (95%CI) of prediabetes, impaired fasting glucose (IFG), impaired glucose tolerance (IGT), and IFG complicated with IGT were 25.1% (14.4%-35.9%), 12.7% (3.2%-22.1%), 8.1% (6.3%-9.8%), and 4.4% (2.3%-6.5%), respectively. After multivariate adjustment, the risk of prediabetes, IFG, IGT, and IFG complicated with IGT increased with the increment of blood pressure (both P for trend <0.05). The positive dose-response relationships between blood pressure levels and risk of prediabetes were also significant among male, urban, and rural residents (both P for trend <0.05), and the interactions between sex and blood pressure showed significant associations for risk of prediabetes and IGT (both P for interaction <0.05). Conclusions: Higher blood pressure levels were associated with an increased risk of prediabetes. The association with prediabetes was stronger in males, but no significant difference was found between urban and rural residents. More distinctive and effective prevention and control strategies should be developed for different populations.


Assuntos
Intolerância à Glucose , Estado Pré-Diabético , Masculino , Humanos , Adolescente , Adulto , Estado Pré-Diabético/epidemiologia , Pressão Sanguínea , Glicemia , Intolerância à Glucose/epidemiologia , Intolerância à Glucose/complicações , Inquéritos e Questionários , Jejum
3.
Eur Rev Med Pharmacol Sci ; 25(2): 738-748, 2021 01.
Artigo em Inglês | MEDLINE | ID: mdl-33577028

RESUMO

OBJECTIVE: In many cancers, long non-coding RNAs (lncRNA) are largely involved; they can regulate cell proliferation, migration, and invasion. However, the research of lncRNA regulation on pancreatic ductal adenocarcinoma is vacant. The aim of this article was to lucubrate the specific role of lncRNA LUCAT1 in regulating the progression of pancreatic cancer. PATIENTS AND METHODS: Pancreatic cancer and adjacent tissues were collected, and the expression of LUCAT1, one potential involved LucRNA, was measured using real-time qPCR (RT-qPCR). Different pathological types of pancreatic cancer cell lines were cultured, and the expression difference of LncRNA LUCAT1 was detected by RT-qPCR, and two cell lines were selected for downstream experiments. si-RNA was used to knockdown the expression of LUCAT1, comparing the difference in expression of LUCAT1, characterizing cell proliferation by MTT and BrdU staining, detecting apoptosis, and cell cycle changes by flow cytometry. Meanwhile, Western blotting was used for the detection of cyclin expression and thus investigate two important associated signaling pathways. Besides, the expression of signaling pathway was validated by signaling inhibitor. RESULTS: In comparison to normal cells, LUCAT1 was highly expressed in human pancreatic cancer cell lines (p<0.05). The higher expression of LUCAT1 resulted in enhanced pathogenesis of PDA cells and motivated the development to S phase by regulation of cyclin D1, CDK4. Furthermore, LUCAT1 promoted PDA cells development by inducing AKT's and p38 MAPK's phosphorylation. CONCLUSIONS: LUCAT1, as the key factor, played a positive role in the proliferation and invasion of pancreatic cells via AKT/MAPK signaling.


Assuntos
Neoplasias Pancreáticas/metabolismo , Proteínas Proto-Oncogênicas c-akt/metabolismo , RNA Longo não Codificante/metabolismo , Proliferação de Células , Humanos , Neoplasias Pancreáticas/patologia , Fosforilação , RNA Longo não Codificante/genética , Células Tumorais Cultivadas
4.
Eur Rev Med Pharmacol Sci ; 23(13): 5558-5566, 2019 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-31298307

RESUMO

OBJECTIVE: To measure the expression level of long non-coding ribonucleic acids (lncRNAs) differentiation antagonizing non-protein coding RNA (DANCR) in serum of patients with fracture and investigate its influences on the proliferation and differentiation of osteoblasts. PATIENTS AND METHODS: Serum samples were collected from 44 fracture patients treated in our hospital and 24 healthy people receiving physical examination in our hospital. Then, reverse transcription-polymerase chain reaction (RT-PCR) technique was used to detect the expression of lncRNA DANCR in the serum of patients with fracture and healthy subjects. MC3T3-E1 mouse osteoblast cell line with stably-knocked out DANCR was further established using small interfering RNAs (siRNAs), and the effect of DANCR knockout on the proliferation of osteoblasts was determined using cell counting kit-8 (CCK-8). At the same time, 5-Ethynyl-2'-deoxyuridine (EdU) staining assay was performed to detect the percentage of EdU-positive cells in osteoblasts in control group and DANCR knockout group. In addition, the mRNA levels of differentiation-related genes including Runt-related transcription factor 2 (Runx2), Collagen1α1, osteocalcin (OC) and osterix (OSX) were detected via RT-PCR, and the protein level of Runx2 was measured through Western blotting. Moreover, osteoblasts were cultured with osteogenic medium for 14 d, and then alizarin red staining and alkaline phosphatase (ALP) staining assays were carried out to examine the differentiation of these osteoblasts. Lastly, Western blotting technique was employed to analyze the expression of the Wnt/ß-catenin signaling pathway. RESULTS: The expression of lncRNA DANCR was significantly increased in the serum of fracture patients (p<0.05). The results of in-vitro cell experiments showed that the intervention of DANCR with siRNA was able to clearly promote the proliferation and differentiation of MC3T3-E1 osteoblast cell line. According to the results of Western blotting, DANCR promoted the apoptosis and proliferation, which was mediated by the activated Wnt/ß-catenin signaling pathway in osteoblasts. CONCLUSIONS: LncRNA DANCR inhibition can facilitate the proliferation and differentiation of osteoblasts by activating the Wnt/ß-catenin signaling pathway in osteoblasts. Therefore, DANCR is expected to be a new target promoting fracture healing.


Assuntos
Diferenciação Celular , Proliferação de Células , RNA Longo não Codificante/metabolismo , Via de Sinalização Wnt , Adulto , Animais , Estudos de Casos e Controles , Linhagem Celular , Subunidade alfa 1 de Fator de Ligação ao Core/genética , Subunidade alfa 1 de Fator de Ligação ao Core/metabolismo , Fraturas Ósseas/metabolismo , Fraturas Ósseas/patologia , Humanos , Camundongos , Pessoa de Meia-Idade , Osteoblastos/citologia , Osteoblastos/metabolismo , Osteocalcina/genética , Osteocalcina/metabolismo , Osteogênese , Interferência de RNA , RNA Longo não Codificante/antagonistas & inibidores , RNA Longo não Codificante/sangue , RNA Longo não Codificante/genética , RNA Interferente Pequeno/metabolismo
5.
Brain Res Mol Brain Res ; 16(1-2): 64-70, 1992 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-1334201

RESUMO

We determined the concentration of the messenger RNA species which encode four (m1-m4) of the five cloned muscarinic receptors in brains of Alzheimer's disease patients as compared to age-matched controls. Assays were performed using the quantitative method of DNA-excess solution hybridization in the cerebral cortex (frontal, temporal and occipital), hippocampus, nucleus basalis of Meynert and brainstem. The results suggest a statistically significant decrease in the m1 muscarinic receptor message in the temporal and occipital cortex, with no change in other regions. There was no change in the level of mRNA encoding the m2, m3 or m4 receptors in any of the brain regions studied.


Assuntos
Doença de Alzheimer/genética , Encéfalo/metabolismo , Código Genético/genética , RNA Mensageiro/metabolismo , Receptores Muscarínicos/genética , Idoso , Doença de Alzheimer/metabolismo , Sondas de DNA , DNA de Cadeia Simples/genética , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Hibridização de Ácido Nucleico , Valores de Referência
6.
Brain Res Mol Brain Res ; 55(1): 35-44, 1998 Mar 30.
Artigo em Inglês | MEDLINE | ID: mdl-9645958

RESUMO

We investigated a potential role for the soluble interleukin-6 receptor (sIL-6R) in modulating interleukin-6 (IL-6) function in the central nervous system by assessing IL-6 and sIL-6R effects on beta-amyloid precursor protein (beta-APP) transcription and expression in cells of human neuronal origin. Cells transfected with a luciferase reporter plasmid containing a 3.8 kb DNA fragment of the beta-APP promoter were shown to have inducible promoter activity when treated with phorbol ester or basic fibroblast growth factor, but not when treated with lipopolysaccharide or Il-6. PCR amplification analysis revealed the presence of mRNA encoding the signaling subunit of the Il-6 receptor complex, the gp130 subunit, at levels approximating that found in human cortical tissue. The mRNA encoding the IL-6 receptor, however, was poorly expressed and was detectable only at high amplification cycles. When purified sIL-6R protein was added together with IL-6, there was a rapid induction of promoter activity within 2 h of stimulation followed by elevations in protein levels of both cell-associated and secreted beta-APP. Analysis of mRNA transcripts from human cortical brain tissue and cell cultures derived from fetal human brain demonstrated the presence of an alternatively spliced secreted form of the IL-6 receptor mRNA, suggesting that cells of the central nervous system may themselves be a source of sIL-6R protein. The capacity for sIL-6R to enhance IL-6 function and broaden the IL-6 target cell population in the brain has implications for the regulation of beta-APP expression in disease states such as Alzheimer's disease where elevations in brain IL-6 levels have been reported.


Assuntos
Precursor de Proteína beta-Amiloide/biossíntese , Encéfalo/metabolismo , Regulação da Expressão Gênica/efeitos dos fármacos , Interleucina-6/farmacologia , Receptores de Interleucina-6/fisiologia , Transcrição Gênica/efeitos dos fármacos , Doença de Alzheimer/genética , Doença de Alzheimer/metabolismo , Sequência de Aminoácidos , Precursor de Proteína beta-Amiloide/genética , Antígenos CD/biossíntese , Antígenos CD/genética , Sequência de Bases , Encéfalo/citologia , Encéfalo/embriologia , Receptor gp130 de Citocina , Proteínas Fetais/biossíntese , Proteínas Fetais/genética , Fator 2 de Crescimento de Fibroblastos/farmacologia , Genes Reporter , Humanos , Lipopolissacarídeos/farmacologia , Luciferases/biossíntese , Glicoproteínas de Membrana/biossíntese , Glicoproteínas de Membrana/genética , Dados de Sequência Molecular , Proteínas de Neoplasias/biossíntese , Proteínas de Neoplasias/genética , Neuroblastoma/patologia , Neurônios/efeitos dos fármacos , Neurônios/metabolismo , Reação em Cadeia da Polimerase , RNA Mensageiro/biossíntese , RNA Mensageiro/genética , Receptores de Interleucina-6/biossíntese , Receptores de Interleucina-6/genética , Proteínas Recombinantes de Fusão/biossíntese , Solubilidade , Acetato de Tetradecanoilforbol/farmacologia , Transfecção , Células Tumorais Cultivadas
7.
Eur J Pharmacol ; 291(2): R1-2, 1995 Oct 15.
Artigo em Inglês | MEDLINE | ID: mdl-8566158

RESUMO

Chinese hamster ovary (CHO) cells are commonly used for expression of the genes of cloned neurotransmitter receptors to study their pharmacology and coupling to signal transduction pathways. It is usually assumed that host cells do not endogenously express the specific receptor under consideration. We demonstrate in this report that CHO cells contain endogenous functional muscarinic acetylcholine receptors which, in some circumstances, might complicate interpretation of data related to the properties of exogenously expressed receptors.


Assuntos
Expressão Gênica , Receptores Colinérgicos/metabolismo , Receptores Muscarínicos/metabolismo , Animais , Células CHO , Cricetinae , GMP Cíclico/biossíntese , Relação Dose-Resposta a Droga
8.
Eur J Pharmacol ; 296(1): 113-8, 1996 Jan 18.
Artigo em Inglês | MEDLINE | ID: mdl-8720484

RESUMO

The selectivity of heparin in inducing potentiation of binding of antagonist ligands to muscarinic receptors was investigated at the five known subtypes of muscarinic receptors. The effects of heparin on binding of [3H]N-methylscopolamine at equilibrium was studied in Chinese hamster ovary (CHO) cells which express each of the individual muscarinic receptor subtypes and in membranes prepared from these cells. Heparin markedly increased equilibrium binding of subsaturating concentrations of the ligand only in membranes of CHO cells which express muscarinic M2 receptors. These effects of heparin were qualitatively similar to those obtained in heart membranes. In contrast, heparin did not influence ligand binding to muscarinic M2 receptors in intact cells. The positive cooperative effects of heparin at muscarinic receptors were abolished following treatment of cells with pertussis toxin. The latter treatment by itself resulted in a significant increase in [3H]N-methylscopolamine binding. Taken together with previous reports of heparin-induced uncoupling of receptors and G-proteins, these data suggest that the effects of heparin on ligand binding to muscarinic M2 receptors might be due to disruption of receptor-G-protein interactions which results in enhancement of binding of antagonist ligands to the receptor.


Assuntos
Anticoagulantes/farmacologia , Proteínas de Ligação ao GTP/metabolismo , Heparina/farmacologia , Parassimpatolíticos/metabolismo , Receptores Muscarínicos/efeitos dos fármacos , Derivados da Escopolamina/metabolismo , Sítio Alostérico , Animais , Células CHO/metabolismo , Cricetinae , Ligantes , Mutação , N-Metilescopolamina , Receptor Muscarínico M2 , Receptores Muscarínicos/química , Receptores Muscarínicos/metabolismo
9.
Neurosci Lett ; 145(2): 149-52, 1992 Oct 12.
Artigo em Inglês | MEDLINE | ID: mdl-1465211

RESUMO

We compared the concentration of mRNA encoding the m1 and m2 muscarinic receptors in several brain regions obtained from young (5-8 months) and aged (24-28 months) male Fischer 344 rats. DNA-excess solution hybridization was employed as a quantitative measure of mRNA concentration. The results indicate the absence of changes in the m1 receptor message with aging in the cerebral cortex, hippocampus and striatum. While there was no statistically significant aging-associated alteration in the concentration of the message encoding the m2 receptor in the thalamus, midbrain, cerebellum and brainstem, there was a decrease in the message level in the hypothalamus.


Assuntos
Envelhecimento/metabolismo , Química Encefálica/fisiologia , RNA Mensageiro/biossíntese , Receptores Muscarínicos/biossíntese , Animais , Hibridização In Situ , Masculino , Ratos , Ratos Endogâmicos F344
10.
Life Sci ; 48(26): 2579-84, 1991.
Artigo em Inglês | MEDLINE | ID: mdl-2046480

RESUMO

Relationship between in vivo down-regulation of cardiac muscarinic receptors and changes in their encoding mRNA was investigated. Rats were treated either once or for ten days with an irreversible inhibitor of acetylcholinesterase, followed by measurements of cardiac acetylcholinesterase, the density and affinity of muscarinic receptors, and the concentration of mRNA coding for these receptors. mRNA was quantitated using the sensitive method of DNA-excess solution hybridization. Our data indicate that while short-term treatment resulted in a marked decrease in the density of cardiac muscarinic receptors by 34%, there was no accompanying significant change in the concentration of their mRNA. In contrast, long-term inhibition of acetylcholinesterase significantly decreased the concentration of both receptors and mRNA by 40% and 29%, respectively. These results are indicative of multiple mechanisms of down-regulation of cardiac muscarinic receptors, some of which might involve alterations at the transcriptional level.


Assuntos
DNA/metabolismo , Isoflurofato/farmacologia , Miocárdio/metabolismo , RNA Mensageiro/efeitos dos fármacos , Receptores Muscarínicos/efeitos dos fármacos , Acetilcolinesterase/metabolismo , Animais , Sequência de Bases , Inibidores da Colinesterase/farmacologia , DNA/genética , Sondas de DNA , Regulação para Baixo , Masculino , Dados de Sequência Molecular , Miocárdio/enzimologia , Hibridização de Ácido Nucleico , Ratos , Ratos Endogâmicos , Receptores Muscarínicos/fisiologia
11.
Funct Neurol ; 16(1): 3-10, 2001.
Artigo em Inglês | MEDLINE | ID: mdl-11396269

RESUMO

The thalamo-(fronto)cortical circuit is involved in sleep regulation, and its dysfunction might contribute to the pathophysiology of chronic primary insomnia. To obtain more evidence of the involvement of the circuit, we studied 23 patients with chronic primary insomnia and 28 healthy volunteers via the assessment of mismatch negativity (MMN) elicited by tone intensity deviance, and of personality traits measured by Zuckerman's Sensation Seeking Scales, and Zuckerman-Kuhlman's Personality Questionnaire. In insomniacs, MMN amplitude at Fz was significantly larger; Depression, which was measured by Plutchik-van Praag's Depression Inventory, and Neuroticism-anxiety and Impulsivity scores were higher, while the Thrill and adventure seeking score was lower; MMN amplitude was positively correlated with Depression and with Impulsivity. In healthy subjects, MMN amplitude at Fz was positively correlated with Neuroticism-anxiety, but negatively with Experience seeking. The larger MMN and distinct personality traits suggest a hyperactivity in the thalamo-(fronto)cortical neuronal circuit in insomniacs, which is probably the result of weak thalamic gating mechanisms, or an imbalance of several neurotransmitter systems.


Assuntos
Variação Contingente Negativa/fisiologia , Lobo Frontal/fisiopatologia , Rede Nervosa/fisiopatologia , Personalidade/fisiologia , Distúrbios do Início e da Manutenção do Sono/fisiopatologia , Tálamo/fisiopatologia , Adulto , Nível de Alerta/fisiologia , Mapeamento Encefálico , Doença Crônica , Feminino , Humanos , Masculino , Inventário de Personalidade , Distúrbios do Início e da Manutenção do Sono/psicologia
15.
Zhong Xi Yi Jie He Za Zhi ; 11(4): 209-11, 196, 1991 Apr.
Artigo em Zh | MEDLINE | ID: mdl-1773456

RESUMO

301 cases of bronchial asthma (BA) in observation group were treated by kahusu [each tablet contained 50 mg heat-killed BCG and 50 mg huercaosu] with the oral administration 1 tablet each time, 3 times each week and 30 cases of BA in control group were treated by heat-killed BCG (each tablet contained 100mg) with the oral administration 1 tablet 3 times each week. Each treatment course was 3 months in both groups. After 1 year's treatment the effective rates of these 2 groups were 81.40% and 80% respectively, and during 2 years follow-up the effective rates of both groups were 44.83% and 42.31% respectively. It was not statistically significant between both groups. The therapeutic effects were associate with the type and the condition of BA. Laboratory examination showed that IgG, IgA value increased, PHA and OT test strengthened and C3 lowered clearly. It indicated that both cellular and humoral immunity had been strengthened and inflammation had been resolved. In the course of treatment no side effect had been found.


Assuntos
Adjuvantes Imunológicos/uso terapêutico , Asma/terapia , Vacina BCG/uso terapêutico , Medicamentos de Ervas Chinesas/uso terapêutico , Extratos Vegetais/uso terapêutico , Administração Oral , Adolescente , Adulto , Vacina BCG/administração & dosagem , Criança , Combinação de Medicamentos , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Mycobacterium bovis
16.
Recept Signal Transduct ; 6(1): 43-52, 1996.
Artigo em Inglês | MEDLINE | ID: mdl-8933621

RESUMO

Muscarinic acetylcholine receptors contain two highly conserved tyrosine residues that are located within or at the extracellular border of the second transmembrane domain and are unique to this subfamily of G protein-coupled receptors. These tyrosine residues are located at positions 82 and 85 of the sequence of the m1 subtype of muscarinic receptors. In this article, we studied the involvement of these two residues in ligand binding to and agonist-induced activation of this receptor subtype using site-directed mutagenesis. Our data suggest for the first time an important role of these two tyrosines in muscarinic receptor function. Evidence is also provided that although the aromatic moiety of these tyrosine residues plays a role in antagonist binding, both this moiety and the tyrosine phenolic hydroxyl group are involved in agonist binding and receptor activation. The results are discussed in terms of a possible relationship of these two tyrosine residues and other conserved tyrosine moieties located in different transmembrane segments. All of these residues might contribute in concert, albeit to different degrees, to the process of ligand binding and receptor activation. The present findings are expected to further our current understanding of the muscarinic receptor domains involved in these processes.


Assuntos
Receptores Muscarínicos/química , Receptores Muscarínicos/metabolismo , Animais , Sítios de Ligação/genética , Células CHO , Carbacol/metabolismo , Sequência Conservada , Cricetinae , Hidrólise , Ligantes , Estrutura Molecular , Mutagênese Sítio-Dirigida , N-Metilescopolamina , Fosfatidilinositóis/metabolismo , Ensaio Radioligante , Ratos , Receptor Muscarínico M1 , Receptores Muscarínicos/genética , Derivados da Escopolamina/metabolismo , Tirosina/química
17.
Pharmacology ; 53(5): 271-80, 1996 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-8990485

RESUMO

The selectivity of coupling of m1, m3, and m5 muscarinic receptors to activation of the neuronal type of nitric oxide synthase was investigated. Stimulation with the agonist carbachol of all three receptor subtypes expressed in Chinese hamster ovary cells resulted in a rapid and transient activation of the enzyme, as measured by stimulation of guanylate cyclase in reporter neuroblastoma cells. Carbachol was more potent and efficacious at m5 receptors than at the other two receptor subtypes. Stimulation of all three muscarinic receptors resulted in an increased concentration of intracellular calcium, with a time course that preceded activation of nitric oxide synthase. At each receptor subtype, there was a close relationship between the magnitude of the maximal calcium response and that of enzyme activation.


Assuntos
Neurônios/enzimologia , Óxido Nítrico Sintase/metabolismo , Receptores Muscarínicos/metabolismo , Animais , Células CHO , Carbacol/farmacologia , Cricetinae , GMP Cíclico/biossíntese , Relação Dose-Resposta a Droga , Ativação Enzimática , Cinética , Agonistas Muscarínicos/farmacologia , Ratos , Receptores Muscarínicos/classificação , Proteínas Recombinantes/classificação , Proteínas Recombinantes/metabolismo , Células Tumorais Cultivadas
18.
J Pharmacol Exp Ther ; 268(2): 552-7, 1994 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-7509388

RESUMO

The coupling of m5 muscarinic acetylcholine receptors to the generation and release of nitric oxide (NO) was investigated. Chinese hamster ovary cells, which stably express m5 receptors, were transiently transfected with the gene encoding neuronal NO synthase and used as a model system. Increased generation of NO upon stimulation of cells by muscarinic agonists was detected by an increase in cyclic GMP in admixed mouse neuroblastoma N1E-115 cells or more directly by measuring the conversion of L-arginine into L-citrulline. Carbachol increased cyclic GMP formation in the mixture of cells in a time- and concentration-dependent manner, with a half-maximal response occurring in the nanomolar range. This response was significantly attenuated by scavengers of NO or inhibitors of NO synthase. This high potency of carbachol was also observed in measurements of L-citrulline formation. A series of muscarinic agonists were as efficacious as carbachol in stimulating NO synthase, whereas McN-A-343 and pilocarpine were partial agonists in this regard. Evidence for an exceptionally high efficiency of coupling of m5 receptors to this response and its possible implication in the interaction between cholinergic and dopaminergic neurotransmission is discussed.


Assuntos
Aminoácido Oxirredutases/metabolismo , Receptores Muscarínicos/fisiologia , Animais , Células CHO , Cálcio/metabolismo , Carbacol/farmacologia , Cricetinae , Cricetulus , GMP Cíclico/biossíntese , Ativação Enzimática , Camundongos , Óxido Nítrico/metabolismo , Óxido Nítrico Sintase , Células Tumorais Cultivadas
19.
Mol Pharmacol ; 45(3): 517-23, 1994 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-8145736

RESUMO

An exceptionally conserved sequence that is shared among most G protein-coupled neurotransmitter receptors is an aspartate-arginine-tyrosine triplet that is located at the amino terminus of the putative second cytoplasmic domain, where the arginine residue is invariant. Using the m1 subtype of muscarinic acetylcholine receptors as an example, we induced a point mutation of the arginine residue at position 123 into asparagine. This mutation resulted in a precipitous decrease in the coupling of m1 receptors to activation of phosphoinositide hydrolysis, in spite of the expression of the wild-type and mutant receptors at similar concentrations in Chinese hamster ovary cells. There were no significant effects on antagonist or partial agonist binding. In marked contrast, whereas binding of the full agonist carbachol to wild-type receptors exhibited high and low affinity components, this agonist bound to a single low affinity state in asparagine-123 mutant cells. Furthermore, agonist-induced enhancement of the specific binding of guanosine-5'-O-(3-[35S] thio)triphosphate was not observed in membranes of cells expressing the mutant receptor. A similar mutation in the m2 muscarinic receptor resulted in a significant but smaller decrease in its coupling to inhibition of cAMP formation. On the other hand, a point mutation of tyrosine-124 in the m1 receptor sequence produced less marked changes in agonist-induced phosphoinositide hydrolysis and no effects on agonist or antagonist binding to the receptor. Taken together, our data demonstrate for the first time that this highly conserved arginine residue plays an important role in coupling of muscarinic receptors to signal transduction mechanisms.


Assuntos
Arginina/química , Sequência Conservada , Proteínas de Ligação ao GTP/metabolismo , Receptores Muscarínicos/metabolismo , Receptores de Neurotransmissores/metabolismo , Sequência de Aminoácidos , Animais , Sítios de Ligação , Células CHO , Cricetinae , Ligantes , Mutagênese Sítio-Dirigida , Ratos , Receptores Muscarínicos/química , Receptores de Neurotransmissores/química , Transdução de Sinais , Tirosina/química
20.
Pharmacology ; 51(5): 298-307, 1995 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-8584581

RESUMO

The first putative extracellular domains of both m1 and m2 muscarinic receptors contain a triplet of amino acid residues consisting of leucine (L), tyrosine (Y), and threonine (T). This triplet is repeated as LYTLYT in m2 receptors. However, it is repeated in a transposed fashion (LYTTYL) in the sequence of m1 receptors. In this work we employed site-directed mutagenesis to investigate the possible significance of this unique sequence diversity in determining the distinct differential drug-receptor interaction at the two receptor subtypes. Mutation of the LYTTYL sequence of m1 receptors to the corresponding m2 receptor LYTLYT sequence, however, did not significantly change the binding affinity of the agonist carbachol or the affinity of the majority of a series of receptor antagonists which are able to discriminate between wild-type m1 and m2 receptors. The reverse mutation at the m2 receptor also did not modify agonist affinity, but altered affinity of several receptor subtype-selective antagonists. The magnitude of affinity changes, however, was small, and the direction of these changes was opposite to what would be expected if the m2 receptor LYTLYT seqence were important for determining the binding profile of m2-receptor-selective antagonists. Our data suggest that the LYTTYL-LYTLYT sequence differences between ml and m2 muscarinic receptors are not important for determining receptor pharmacology.


Assuntos
Receptores Muscarínicos/efeitos dos fármacos , Sequência de Aminoácidos , Animais , Células CHO , Carbacol/farmacologia , Cricetinae , DNA Complementar/metabolismo , Espaço Extracelular/efeitos dos fármacos , Técnicas In Vitro , Dados de Sequência Molecular , Agonistas Muscarínicos/farmacologia , Ensaio Radioligante , Ratos
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