Efeito do consumo de etanol em padrão binge sobre o estresse oxidativo sistêmico / Effect of ethanol consumption in a binge pattern on systemic oxidative stress

O consumo intermitente de etanol, denominado binge drinking está relacionado a prejuízos para a saúde do indivíduo. Binge drinking descreve o padrão de consumir bebidas alcoólicas que resulta em concentração sanguínea de etanol igual ou superior a 0,08 g/dL (consumo de 70/56 gramas de etanol para homens/ mulheres) em um período de 2 horas. Os mecanismos que medeiam os danos orgânicos induzidos pelo consumo de etanol em padrão binge não são conhecidos. Portanto, o desenvolvimento de modelos experimentais que permitam o melhor entendimento desses mecanismos é de interesse. A hipótese desse estudo é a de que o consumo em binge ative os receptores AT1 que irá promover aumento do estresse oxidativo sistêmico. Portanto, o presente projeto foi delineado de forma a investigar a participação dos receptores AT1 no estresse oxidativo sistêmico induzido pelo consumo de etanol em padrão binge. Com esse propósito, ratos Wistar Hannover com idade entre 60 e 70 dias (270 a 300 g) foram distribuídos aleatoriamente em 4 grupos: 1) Controle: os animais tiveram livre acesso a água e receberam diariamente água por gavagem; 2) Etanol binge: os animais tiveram livre acesso a água e receberam etanol na dose de 2 g/kg (10 mL/kg de uma solução 26% v./v.) por gavagem por período de 5 semanas. A administração de etanol foi realizada 4 dias por semana; 3) Losartan: os animais tiveram livre acesso a água e receberam losartan (10 mg/kg) diariamente por gavagem; 4) Etanol binge + losartan: os animais tiveram livre acesso a água e receberam etanol na dose de 2 g/kg por gavagem por período de 5 semanas. Esses animais também receberam losartan (10 mg/kg) diariamente por gavagem. Ao término do tratamento os animais foram anestesiados com uretana 1,25 g/kg em solução 25% (5 mL/kg) e mortos por exsanguinação seguida do rompimento do diafragma. O sangue e o coração (ventrículo esquerdo) foram coletados para realização de análises bioquímicas. O tratamento com etanol não alterou o peso dos animais ao longo do tratamento. Não foram detectadas diferenças do consumo de ração e de água entre os grupos ao longo das 5 semanas de tratamento. Os resultados mostraram que o consumo de etanol em padrão binge não alterou a concentração plasmática de substâncias reativas ao ácido tiobarbitúrico (TBARS) e do peróxido de hidrogênio (H2O2) bem como a atividade plasmática das enzimas superóxido dismutase (SOD), da concentração plasmática de glutationa reduzida (GSH) e da atividade plasmática da catalase. Perfil semelhante foi observado no ventrículo esquerdo, além da não observação da expressão proteica da ERK 1/2. Com isso, o consumo de etanol em binge não alterou o estresse oxidativo sistêmico e tecidual ou alteração dos sistemas de defesa antioxidante.

Intermittent consumption of ethanol, called binge drinking, is related to damage to the individual's health. Binge drinking describes the pattern of consuming alcoholic beverages that results in blood ethanol concentration equal to or greater than 0.08 g / dL (consumption of 70/56 grams of ethanol for men / women) in a period of 2 hours. The mechanisms that mediate organic damage induced by ethanol consumption in a binge pattern are not known. Therefore, the development of experimental models that allow a better understanding of these mechanisms is of interest. The hypothesis of this study is that consumption in binge activates AT1 receptors that will promote an increase in systemic oxidative stress. Therefore, the present project was designed to investigate the participation of AT1 receptors in systemic oxidative stress induced by the consumption of ethanol in a binge pattern. For this purpose, Wistar Hannover rats aged between 60 and 70 days (270 to 300 g) were randomly assigned to 4 groups: 1) Control: the animals had free access to water and received daily water by gavage; 2) Binge ethanol: the animals had free access to water and received ethanol at a dose of 2 g / kg (10 mL / kg of a 26% v./v. Solution) by gavage for a period of 5 weeks. Ethanol was administered 4 days a week; 3) Losartan: the animals had free access to water and received losartan (10 mg / kg) daily by gavage; 4) Ethanol binge + losartan: the animals had free access to water and received ethanol at a dose of 2 g / kg per gavage for a period of 5 weeks. These animals also received losartan (10 mg / kg) daily by gavage. At the end of the treatment, the animals were anesthetized with 1.25 g / kg urethane in 25% solution (5 mL / kg) and killed by exsanguination followed by rupture of the diaphragm. Blood and heart (left ventricle) were collected for biochemical analysis. Treatment with ethanol did not change the weight of the animals during the treatment. There were no differences in feed and water consumption between groups over the 5 weeks of treatment. The results showed that the consumption of ethanol in a binge pattern did not alter the plasma concentration of substances reactive to thiobarbituric acid (TBARS) and hydrogen peroxide (H2O2) as well as the plasma activity of the enzymes superoxide dismutase (SOD), the plasma concentration of reduced glutathione (GSH) and plasma catalase activity. A similar profile was observed in the left ventricle, in addition to not observing ERK 1/2 protein expression. As a result, ethanol consumption in binge did not alter systemic and tissue oxidative stress or alter antioxidant defense systems.

Antidepressant-like Effects Induced by Chronic Blockade of the Purinergic 2X7 Receptor through Inhibition of Non-like Receptor Protein 1 Inflammasome in Chronic Unpredictable Mild Stress Model of Depression in Rats

OBJECTIVE: Purinergic 2X7 receptor (P2X7R) activation is known to be involved in pathogenesis of depression. Our aims were to investigate P2X7R-activated inflammasome pathways in parallel with induction of depression and to test the antidepressant-like effects of the selective P2X7R antagonist Brilliant Blue G (BBG) in a rat model of chronic unpredictable mild stress (CUMS). METHODS: Male Wistar albino rats were divided into control, CUMS, CUMS+BBG25 (25 mg/kg/day) and CUMS+BBG50 (50 mg/kg/day) groups (n=10 for each group). Various stressors were applied to rats for 6 weeks to establish the CUMS model and daily BBG treatment was started at the end of 3rd week. Sucrose preference test and forced swim test (FST) were performed to assess antidepressant-like effects. Brain samples were obtained for real-time polymerase chain reaction and immunohistochemistry analysis. RESULTS: In FST, duration of immobility was reduced in the CUMS+BBG50 group. Also, BBG treatment significantly enhanced sucrose preference. While NLRP3 gene expression levels were unchanged in rats exposed to the CUMS protocol, expression levels of other inflammasome pathway factors NLRP1, caspase-1, ASC, NF-κB, IL-1β, IL-6 and P2X7R were increased. BBG treatment reduced expression levels of these factors. Likewise, Iba-1 and GFAP immunoreactivities were enhanced by the CUMS protocol and this action was reversed by BBG treatment. CONCLUSION: Chronic administration of BBG in CUMS model results in antidepressant-like activity in a dose dependent manner. Molecular and histological results show that these effects might be at least partially related to the suppression of inflammasome-related neuroinflammatory responses and suggest involvement of NLRP1 in depression.

Identificação de novos antagonistas para receptores purinérgicos P2 / Identification of new antagonists for P2 purinergic receptors

Os receptores purinérgicos P2 são receptores expressos na membrana plasmática de diversos tipos celulares humanos, nos quais exercem importantes funções fisiológicas . Eles são divididos em duas classes, de acordo com a estrutura apresentad a . A classe P2X comp reende os subtipos de receptores ionotrópicos que são ativados fisiologicamente pelo ATP. Dentre os receptores P2X, o P2X7 destaca se por suas funções associadas à dor e à inflamação. Já a classe P2Y compreende os subtipos de receptores metabotrópicos, os quais são ativados por diferentes nucleotídeos extracelulares. Nes s a última classe, o subtipo P2Y2 destaca se p elos seus papeis desempenhados na inflamação e no câncer, enquanto o P 2Y4 se sobressai pela escassez de informações acerca de suas funções fisiol ógicas devido a limitações de caráter farmacológico . Apesar de serem considerados importantes alvos terapêuticos , ainda não existe m fármacos com atuação sobre ess es receptores que sejam aprovados para uso clínico , o que encoraja a busca por novas moléculas com atividade antagonista. Ness e contexto, o objetivo des t e estudo foi identificar novos antagonistas para receptores P2 (P2X7, P2Y2 e P2Y4) e averiguar se eles exercem algum papel n a atenuação da dor e inflamação Na primeira part e dess e trabalho foi identificada a atividade antagonista d o extrato galhos de Joannesia princeps Vell. após a realização de uma mini campanha de triagem. Utilizando a técnica de mensuração de cálcio intracelular, foi demonstrado que esse extrato foi capaz de inibir a mobiliza ção de cálcio induzida por UTP de forma concentração dependente, sendo que esse efeito não foi provocado por citotoxicidade ou fenômeno quenching. (AU)

Além disso, esse extrato também foi capaz de inibir parcialmente a mobilização de cálcio induzida por UDP . Co m isso , os resultados sugerem uma possível seletividade quanto à ação antagonista desse extrato sobre os receptores P2Y ativados por nucleotídeos derivados da uridina. Enquanto isso, na segunda parte do trabalho foi identificada a atividade antagonista d a molécula CS 15 sobre o receptor P2X7 durante a realização de uma mini campanha de triagem . A molécula CS 15 , um triterpeno isolado da planta Clusia studartiana C. M. Vieira & Gomes da Silva foi capaz de inibir a captação do corante YO PRO 1 em ensaios de permeabilização celular de forma concentração dependente e apresentou um IC 50 na faixa de nanomolar. A demais , ess a molécula não demonstrou toxicidade in vitro e ainda foi capaz de aliviar os sintomas de nocicepção em modelo experimental animal. Coletivamen te, os resultados apontam para a descoberta de novos antagonistas para receptores P2 de origem natural , os quais podem contribuir no futuro para o escasso campo da terapia associada aos receptores purinérgicos. (AU)

Effects of ATP on Pacemaker Activity of Interstitial Cells of Cajal from the Mouse Small Intestine / 전남의대학술지

Purinergic receptors play an important role in regulating gastrointestinal (GI) motility. Interstitial cells of Cajal (ICCs) are pacemaker cells that regulate GI smooth muscle activity. We studied the functional roles of external adenosine 5′-triphosphate (ATP) on pacemaker activity in cultured ICCs from mouse small intestines by using the whole-cell patch clamp technique and intracellular Ca²⁺ ([Ca²⁺]ᵢ) imaging. External ATP dose-dependently depolarized the resting membrane and produced tonic inward pacemaker currents, and these effects were antagonized by suramin, a purinergic P2 receptor antagonist. ATP-induced effects on pacemaker currents were suppressed by an external Na⁺-free solution and inhibited by the nonselective cation channel blockers, flufenamic acid and niflumic acid. The removal of external Ca²⁺ or treatment with thapsigargin (inhibitor of Ca²⁺ uptake into endoplasmic reticulum) inhibited the ATP-induced effects on pacemaker currents. Spontaneous [Ca²⁺]ᵢ oscillations were enhanced by external ATP. These results suggest that external ATP modulates pacemaker activity by activating nonselective cation channels via external Ca²⁺ influx and [Ca²⁺]ᵢ release from the endoplasmic reticulum. Thus, it seems that activating the purinergic P2 receptor may modulate GI motility by acting on ICCs in the small intestine.

Papel dos receptores purinérgicos em modelo animal de doença de Parkinson / Role of purinergic receptors in an animal model of Parkinsons Disease

A Doença de Parkinson é uma doença altamente incapacitante e de grande prevalência. Pouco se sabe sobre sua etiologia e os tratamentos atuais consistem na diminuição dos sintomas, uma vez que ainda não foi encontrada uma maneira de reverter o déficit de neurônios dopaminérgicos observados nos pacientes acometidos. Sabe-se que os receptores purinérgicos são encontrados por todo o sistema nervoso central, não só no indivíduo adulto como também em diferentes estágios do desenvolvimento embrionário e estão envolvidos com proliferação e diferenciação celular. Este trabalho estudou a participação dos receptores purinérgicos em modelo animal de doença de Parkinson por lesão dos neurônios dopaminérgicos da via nigroestriatal com 6-OH dopamina (6-OHDA). Realizamos a análise do perfil de expressão gênica dos diferentes receptores após a lesão e subsequente modulação. Observamos expressão gênica alterada dos receptores P2X7 e P2Y6 até 5 semanas após a lesão. O uso do antagonista do receptor P2X7 Brilliant Blue G (BBG) induziu a regeneração da via nigroestriatal e o uso do antagonista do receptor P2Y6 MRS2578 preveniu a morte dos neurônios. Como esses efeitos foram acompanhados pela inativação de células microgliais, supõe-se que o controle do microambiente neuroinflamatório causado pela injeção de 6-OHDA seja a principal causa do efeito antiparkinsoniano observado pelo tratamento com BBG e MRS2578. Além disso, o transplante celular com células precursoras neuraisnão foi capaz de reverter o comportamento hemiparkinsoniano dos animais lesionados. Apesar do uso concomitante com BBG reduzir o comportamento, parece que esse efeito deve-se ao BBG per se, uma vez que o tratamento somente com o antagonista de P2X7 foi mais eficaz. De maneira geral, a modulação da atividade dos receptores purinérgicos se mostrou uma ferramenta promissora na pesquisa de cura e compreensão das bases moleculares da Doença de Parkinson

Parkinson's disease is a highly disabling and prevalent disease. Little is known about its etiology and the current treatments consist in the reduction of the symptoms, since there is no known method to reverse the dopaminergic neurons deficit observed in patients. Purinergic receptors are found throughout the central nervous system, not only in the adult individual but also at different stages of embryonic development, and are involved in proliferation and differentiation. This work investigated the role of purinergic receptors in the animal model of Parkinson's disease induced by 6-OH dopamine (6-OHDA) injection and consequent death of dopaminergic neurons of the nigrostriatal pathway. Patterns of purinergic receptors gene expression after the lesion and subsequent modulation were analyzed. We observed altered gene expression of P2X7 and P2Y6 receptors within 5 weeks of injury. The use of the P2X7 receptor antagonist Brilliant Blue G (BBG) induced the regeneration of the nigrostriatal pathway and treatment with P2Y6 receptor antagonist MRS2578 prevented the death of the neurons. Since these effects were accompanied by the inactivation of microglial cells, it is assumed that the control of neuroinflammatory milieu caused by the 6-OHDA injection is the main cause of the antiparkinsonian effect observed by the treatment with BBG and MRS2578. In addition, transplantation with neural precursor cells was not able to reverse the hemiparkinsonian behavior of injured animals. Although concomitant use with BBG improved cell engraftment, it appears that this effect is due to BBG per se, since treatment with only this P2X7receptor antagonist was more effective. In general, modulation of purinergic receptor activity showed to be a promising tool in the research of cure and understanding of the molecular bases of Parkinson's Disease

Research Progress on Expression and Function of P2 Purinergic Receptor in Blood Cells / 中国实验血液学杂志

Nucleotides have unambiguously emerged as a family of mediators of intercellular communication, which bind a class of plasma membrane receptors, P2 purinergic receptors, to trigger intercellular signaling. P2 receptors can be further divided into two structurally and functionally different sub-famlies, the P2X and P2Y receptors. Different blood cells express diverse spectrum of P2 receptors at different levels. Extracellular adenosine triphosphate (ATP) exerts different effects on blood cells, regulating cell proliferation, differentiation, migration, chemotaxis, release of cytokines or lysosomal constituents, and generation of reactive oxygen or nitrogen species. The relationship between abnormal P2 receptors and human diseases attracts more and more attention. This review briefly discusses the expression and function of P2 receptors in hematopoietic system.

Modulação da diferenciação neural de células troco embrionárias por transientes de cálcio intracelulares: papéis dos receptores purinérgicos e de canais de cálcio voltagem-dependentes / Modulation of neural embryonic stem cell differentiation by intracellular Ca2+ oscillations. Roles of purinergic receptors and voltage gated Ca2+ channels

Receptores purinérgicos e canais de cálcio voltagem-dependentes estão envolvidos em diversos processos biológicos como na gastrulação, durante o desenvolvimento embrionário, e na diferenciação neural. Quando ativados, canais de cálcio voltagem-dependentes e receptores purinérgicos do tipo P2, ativados por nucleotídeos, desencadeiam transientes de cálcio intracelulares controlando diversos processos biológicos. Neste trabalho, nós estudamos a participação de canais de cálcio voltagem-dependentes e receptores do tipo P2 na geração de transientes de cálcio espontâneos e sua regulação na expressão de fatores de transcrição relacionados com a neurogênese utilizando como modelo células tronco (CTE) induzidas à diferenciação em células tronco neurais (NSC) com ácido retinóico. Descrevemos que CTE indiferenciadas podem ter a proliferação acelerada pela ativação de receptores P2X7, enquanto que a expressão e a atividade desse receptor precisam ser inibidas para o progresso da diferenciação em neuroblasto. Além disso, ao longo da diferenciação neural, por análise em tempo real dos níveis de cálcio intracelular livre identificamos 3 padrões de oscilações espontâneas de cálcio (onda, pico e unique), e mostramos que ondas e picos tiveram a frequência e amplitude aumentadas conforme o andamento da diferenciação. Células tratadas com o inibidor do receptor de inositol 1,4,5-trifosfato (IP3R), Xestospongin C, apresentaram picos mas não ondas, indicando que ondas dependem exclusivamente de cálcio oriundo do retículo endoplasmático pela ativação de IP3R. NSC de telencéfalo de embrião de camundongos transgênicos ou pré-diferenciadas de CTE tratadas com Bz-ATP, o agonista do receptor P2X7, e com 2SUTP, agonista de P2Y2 e P2Y4, aumentaram a frequência e a amplitude das oscilações espontâneas de cálcio do tipo pico. Dados, obtidos por microscopia de luminescência, da expressão em tempo real de gene repórter luciferase fusionado à Mash1 e Ngn2 revelou que a ativação dos receptores P2Y2/P2Y4 aumentou a expressão estável de Mash1 enquanto que ativação do receptor P2X7 levou ao aumento de Ngn2. Além disso, células na presença do quelante de cálcio extracelular (EGTA) ou do depletor dos estoques intracelulares de cálcio do retículo endoplasmático (thapsigargin) apresentaram redução na expressão de Mash1 e Ngn2, indicando que ambos são regulados pela sinalização de cálcio. A investigação dos canais de cálcio voltagem-dependentes demonstrou que o influxo de cálcio gerado por despolarização da membrana de NSC diferenciadas de CTE é decorrente da ativação de canais de cálcio voltagem-dependentes do tipo L. Além disso, esse influxo pode controlar o destino celular por estabilizar expressão de Mash1 e induzir a diferenciação neuronal por fosforilação e translocação do fator de transcrição CREB. Esses dados sugerem que os receptores P2X7, P2Y2, P2Y4 e canais de cálcio voltagem-dependentes do tipo L podem modular as oscilações espontâneas de cálcio durante a diferenciação neural e consequentemente alteram o padrão de expressão de Mash1 e Ngn2 favorecendo a decisão do destino celular neuronal

Purinergic receptors and voltage gated Ca2+ channels have been attributed with developmental functions including gastrulation and neural differentiation. Upon activation, nucleotide-activated P2 purinergic receptor and voltage-gated Ca2+ channel subtypes trigger intracellular calcium transients controlling cellular processes. Here, we studied the participation of voltage-gated calcium channels and P2 receptor activity in spontaneous calcium transients and consequent regulation expression of transcription factors related to retinoic acid-induced neurogenesis of mouse neural stem and embryonic stem cells (ESC). In embryonic pluripotent stem cells, proliferation is accelerated by P2X7 receptor activation, while receptor expression / activity needs to be down-regulated for the progress of neuroblast differentiation. Moreover, along neural differentiation time lapse imaging with means of a cytosolic calcium-sensitive fluorescent probe provided different patterns of spontaneous calcium transients (waves and spikes) showing that both, frequency and amplitude increased along differentiation. Cells treated with the inositol 1,4,5-trisphosphate receptor (IP3R) inhibitor Xestospongin C showed spikes but not waves, indicating that waves exclusively depended on calcium release from endoplasmic reticulum by IP3R activation. Cells treated with the P2X7 receptor subtype agonist Bz-ATP and the P2Y2 and P2Y4 receptor 2-S-UTP increased frequency and amplitudes of calcium transients, mainly spikes, in embryonic telencephalon neural stem cells (NSC) and NSC pre-differentiated from ESC. Data obtained by luminescence time lapse imaging of stable transfected cells with Mash1 or Ngn2 promoter-protein fusion to luciferase reporter construct revealed increased Mash1 expression due to activation of P2Y2/P2Y4 receptor subtypes, while increased expression of Ngn2 was observed following P2X7 receptor activation. In addition, cells imaged in presence of the extracellular calcium chelator EGTA or following endoplasmic reticulum calcium store depletion by thapsigargin showed a decrease in Mash1 and Ngn2 expression, indicating that both are regulated by calcium signaling. Investigation of the roles of voltage gated Ca2+ channels in neural differentiation showed that Ca2+ influx in NSC pre-differentiated from ESC is due to membrane depolarization and L-type voltage gated Ca2+ channel activation, thereby controlling cell fate decision, by stabilizing the expression of MASH1 and inducing differentiation, by phosphorylation of the transcription factor CREB. Altogether these data suggest that P2X7, P2Y2, P2Y4 receptors and L-type voltage gated Ca2+ channels can modulate spontaneous calcium oscillations during neural differentiation and consequently change the Mash1 and Ngn2 expression patterns, thus favoring the cell fate decision to the neuronal phenotype

Platelet Function Assay for Clopidogrel and Ticlopidine in Patients With Ischemic Stroke

BACKGROUND: The rapid platelet function assay (RPFA) has recently been developed and used to monitor the antiplatelet effects on the P2Y12 ADP receptor. We describe the platelet response to clopidogrel and ticlopidine using the RPFA and identify the clinical factor related to laboratory resistance in patients with ischemic stroke. METHODS: Of the 172 outpatients with ischemic stroke or transient ischemic attack (TIA) enrolled in this study, 86 were taking clopidogrel (75 mg/day) and 86 were taking ticlopidine (500 mg/day). Demographic data, vascular risk factors, stroke subtypes, and the results of blood tests were recorded. Inhibition is described as the percentage change from baseline aggregation, and is calculated from the P2Y12 reaction unit (PRU) and the base PRU on the RPFA. Those patients who displayed ineffective aggregation-inhibition (inhibition <20%) on the RPFA were defined as nonresponders. RESULTS: The response of platelet aggregation-inhibition to clopidogrel and ticlopidine exhibited a variable distribution (PRU; coefficient of variability, 0.477). Ineffective platelet inhibition was detected in 25.6% of the clopidogrel group and 3.5% of the ticlopidine group (p<0.001). In addition to clopidogrel, TIA and diabetes exhibited significantly higher ineffective platelet inhibition in a univariate analysis. In the multivariate analysis, clopidogrel and TIA remained significant, and diabetes fell to borderline significance (p=0.061). CONCLUSIONS: The response to clopidogrel and ticlopidine can vary between patients. Platelet inhibition is lower for clopidogrel than for ticlopidine on the platelet function test in patients with ischemic stroke. The clinical impact of these results remains uncertain; further investigations are needed.

The Impact of Generic Clopidogrel Bisulfate on Platelet Inhibition in Patients with Coronary Artery Stents: Results of the ACCEL-GENERIC Study

BACKGROUND/AIMS: In patients with coronary artery stents, the cost of clopidogrel has been cited as a factor in the premature discontinuation of therapy. Thus, the introduction of lower-cost generic clopidogrel may increase patient compliance. However, platelet inhibition by generic clopidogrel has not been compared to the original clopidogrel formulation in patients with coronary artery stents. METHODS: We prospectively enrolled 20 patients receiving chronic therapy with the original clopidogrel bisulfate (Plavix(R)). After assessing patient compliance with Plavix(R), maintenance therapy was switched to generic clopidogrel bisulfate (Plavitor(R)). Platelet reactivity was assessed at baseline and 30-day after the switch using conventional aggregometry and the VerifyNow P2Y12 assay. RESULTS: All patients completed maintenance therapy with Plavitor(R). Before and after switching therapy maximal (36.5 +/- 7.9% vs. 39.8 +/- 16.2%, p = 0.280) and late platelet aggregation (23.5 +/- 10.9% vs. 29.1 +/- 18.3%, p = 0.156) with 5 micromol/L adenosine diphosphate (ADP) stimulus did not differ. Likewise, 20 micromol/L ADP-induced platelet aggregation and P2Y12 reaction unit in patients on Plavitor(R) therapy was comparable to that in patients on Plavix(R) therapy. However, Bland-Altman analysis showed wide limits of agreement between measured platelet reactivity on Plavix(R) vs. Plavitor(R) therapies. CONCLUSIONS: Among patients on Plavix(R) maintenance therapy with coronary stents, replacement with Plavitor(R) shows a comparable inhibition of ADP-induced platelet aggregation. However, due to poor inter-therapy agreement, between two regimens, physicians may be cautious when introducing generic clopidogrel bisulfate.

Pharmacological characteristics of contractile responses regulated by P2Y receptors in circular smooth muscle of the rat gastric body / 药学学报

This study is to observe the difference in pharmacological characteristics between circular smooth muscles of rat isolated gastric body and gastric fundus, and to investigate the effects of nucleoside and nucleotide on circular smooth muscle of the rat gastric body and the involved receptors. Circular muscle strips of the rat gastric body and gastric fundus were prepared, and contractile responses to agonists were investigated with a technique of drug-receptor interaction in functional system. There was no significant difference between the circular muscle strips of the gastric body and gastric fundus in the responses to KCl, and no difference in EC50 values of contractile responses for 5-HT and His between the two kinds of preparations (P > 0.05). However, Emax values of contractile responses to 5-HT and His [(0.81 +/- 0.26) and (0.88 +/- 0.27) g] in gastric body were significantly smaller than those in gastric fundus [(2.67 +/- 0.61) and (1.90 +/- 0.68) g, P < 0.01], and EC50 value of CCh produced contractile response [(0.45 +/- 0.15) micromol x L(-1)] in gastric body was significantly higher than that in gastric fundus [(0.20 +/- 0.09) micromol x L(-1), P < 0.01]. In precontracted circular muscle strips of the gastric body, ATP (0.1-3000 micromol x L(-1)) produced only a contractile response concentration-dependently, but the same concentration of ATP induced a biphasic response (relaxation followed by a contraction) in precontracted circular muscle strips of the gastric fundus. ATP, UTP, ADP, 2-MeSATP and alpha,beta-MeATP produced contractile responses concentration-dependently in circular muscle strips of the rat gastric body. The EC50 value for 2-MeSATP [(7.2 +/- 5.2) nmol x L(-1)] was about 500 times lower than that for Ach [(3.47 +/- 1.20) micromol x L(-1)]. The rank order of potency for the contraction was 2-MeSATP>ADP>ATP=UTP>alpha,beta-MeATP>adenosine. The contractile responses to ATP and UTP were not significantly affected by phentolamine, propranolol, atropine or tetrodotoxin. In conclusion, there is a significant difference in pharmacological characteristics between the circular smooth muscles of the rat gastric body and gastric fundus and nucleotides might be important mediators responsible for the contraction via a specific P2Y receptor in circular smooth muscle of the rat gastric body.

Therapeutic potential of extracellular ATP and P2 receptors in nervous system diseases / 神经科学通报·英文版

Extracellular adenosine 5 inch-triphosphate (ATP) is a key signaling molecule present in the central nervous system (CNS), and now is receiving greater attention due to its role as a messenger in the CNS during different physiological and pathological events. ATP is released into the extracellular space through vesicular exocytosis or from damaged and dying cells. Once in the extracellular environment, ATP binds to the specific receptors termed P2, which mediate ATP effects and are present broadly in both neurons and glial cells. There are P2X, the ligand-gated ionotropic receptors, possessing low affinity for ATP and responsible for fast excitatory neurotransmission, and P2Y, the metabotropic G-protein-coupled receptors, possessing high affinity for ATP. Since massive extracellular release of ATP often occurs after stress, brain ischemia and trauma, the extracellular ATP is considered relating to or involving in the pathological processes of many nervous system diseases. Conversely, the trophic functions have also been extensively described for the extracellular ATP. Therefore, extracellular ATP plays a very complex role in the CNS and its binding to P2 receptors can be related to toxic and/or beneficial effects. In this review, we described the extracellular ATP acting via P2 receptors as a potent therapeutic target for treatment of nervous system diseases.

P2Y6 receptor and immunoinflammation / 神经科学通报·英文版

The immunocytes microglia in the central nervous system (CNS) were reported to play a crucial role in neurodegeneration. As a member of P2 receptors family, purinoceptor P2Y6 has attracted much attention recently. Previous studies showed that purinoceptor P2Y6 mainly contributed to microglia activation and their later phagocytosis in CNS, while in immune system, it participated in the secretion of interleukin (IL)-8 from monocytes and macrocytes. So there raises a question: whether purinoceptor P2Y6 also takes part in neuroinflammation? Thus, this review mainly concerns about the properties and roles of purinoceptor P2Y6, including (1) structure of purinoceptor P2Y6; (2) distribution and properties of purinoceptor P2Y6; (3) relationships between purinoceptor P2Y6 and microglia; (4) relationships between purinoceptor P2Y6 and immunoinflammation. Itos proposed that purinoceptor P2Y6 may play a role in neuroinflammation in CNS, although further research is still required.

Clopidogrel hyporesponsiveness

Antiplatelet therapy is a cornerstone in cardiovascular medicine. Aspirin and clopidogrel have emerged as critical therapies in the treatment of cardiovascular disease. Despite their efficacy, patients on these medications continue to suffer complications. Millions of patients are currently on low-dose antiplatelet therapy but it is unknown how many of these patients are under-treated or on the wrong medication. Clopidogrel hypo responsiveness of [resistance] is an emerging clinical entity with potentially severe consequences such as recurrent myocardial infarction, stroke, or death. The mechanism of resistance remains ill-defined, but there are specific clinical, cellular, and genetic factors that influence therapeutic failure. These factors range from physicians who fail o prescribe these medications despite appropriate indications to polymorphisms of platelet membrane glycoproteins. Rapid and accurate diagnosis of antiplatelet resistance also remains an issue as new bedside tests are developed. By understanding the mechanism of therapeutic failure and by improving the diagnosis of this clinical entity, a new era of individualized antiplatelet therapy may arise with routine measurements of platelet activity in the same way that cholesterol, blood pressure, and blood sugar are followed, thus improving the care for millions of people. This review article focuses on the mechanism of clopidogrel actions, available tools and mechanisms to assess and explain its responsiveness in addition to future management options

Monitoring Platelet Inhibition by Clopidogrel Using Rapid Platelet Function Assay in Patients With Ischemic Stroke

BACKGROUND: Clopidogrel inhibits platelet P2Y12 adenosine diphosphate (ADP) receptors and has been widely used in patients with ischemic stroke. However, a considerable number of patients suffer from cerebrovascular events despite the use of clopidogrel. The rapid platelet function assay (RPFA) has been used for monitoring the antiplatelet effects on the P2Y12 ADP receptor. This study was performed to measure the platelet response to clopidogrel using RPFA in patients with ischemic stroke, and to identify the clinical factor related with clopidogrel resistance. METHODS: A total of 86 patients taking clopidogrel (75 mg/day) were enrolled. Demographic data, vascular risk factors, the presence of obesity and metabolic syndrome, drug history, hemoglobin, platelet counts, and stroke subtypes were recorded. RPFA presented the results as P2Y12 Reaction Units (PRU), base PRU (BASE), and Inhibition (%). Inhibition was calculated as (1-PRU/BASE)x100. The patients showing ineffective aggregation- inhibition (percentage of Inhibition < 20) on RPFA were defined as non-responders to clopidogrel. RESULTS: The response of platelet aggregation-inhibition to clopidogrel showed a variable distribution with mean and standard deviation of 32.2+/-22.3%. Twenty four (27.9%) patients showed the inhibition below 20%. There was no difference between responders and non-responders regarding the clinical factors above. We found no influence of co-medication with the statins on platelet response to clopidogrel. CONCLUSIONS: There is a patient variability in response to clopidogrel and a considerable portion of stroke patients have clopidogrel resistance on the platelet function test. The clinical usefulness of routine platelet function test requires further validation.

The Relationship of P2Y1 ADP Receptor Polymorphisms and Ischemic Vascular Disease / 대한혈액학회지

BACKGROUND: The platelet ADP receptor P2Y1 plays a key role in platelet aggregation. METHODS: We tested eight sites of P2Y1 and studied the possible link between the presence of P2Y1 polymorphisms and the risk of is chemic vascular disease in a case-control study. The polymorphisms A1622G, C647G and C2259G were selected according to linkage disequilibrium. We evaluated 275 patients with is chemic cerebrovascular disease and 275 control subjects. We also evaluated 171 patients with acute myocardial infarction (AMI), 166 patients with unstable angina (UA), 173 patients with stable angina (SA) and 188 control subjects. RESULTS: For the cerebrovascular disease patients, A1622G AA, AG [odds ratio (OR), 1.170; 95% confidence interval (CI), 0.784 to 1.748] and GG (OR, 1.031; 95% CI, 0.554 to 1.918) did not show any difference between the case and control subjects. C647G CC, CG (OR, 0.995; 95% CI, 0.639 to 1.550) and GG (OR, 1.012; 95% CI, 0.450 to 2.277) did not show any difference between the case and control subjects. C2259G CC, CG (OR, 0.619; 95% CI, 0.354 to 1.082) and GG did not show any difference between the case and control subjects. For coronary artery disease patients, C2259G GG, CG (for AMI patients OR, 0.880, 95% CI, 0.384 to 2.016; for UA patients, OR, 0.885, 95% CI, 0.410 to 1.911; for SA patients, OR, 1.156, 95% CI, 0.534 to 2.501) and CC did not show any difference between AMI, UA and SA patients and each control subject. C647G GG, CG (for AMI patients OR, 1.351, 95% CI, 0.731 to 2.497; for UA patients OR, 1.292, 95% CI, 0.723 to 2.309; for SA patients OR, 0.977, 95% CI, 0.530 to 1.803) and CC (for AMI patients OR, 0.355, 95% CI, 0.093 to 1.358; for UA patients OR, 0.645, 95% CI, 0.205 to 2.028; for SA patients OR, 0.385, 95% CI, 0.113 to 1.311) did not show any difference between AMI, UA and SA patients and each control subject. A1622G AA, AG (for AMI patients OR, 1.416, 95% CI, 0.786 to 2.549; for UA patients OR, 1.079, 95% CI, 0.611 to 1.904; for SA patients OR, 0.958, 95% CI, 0.529 to 1.732) and GG (for AMI patients OR, 0.525, 95% CI, 0.195 to 1.411; for UA patients OR, 0.568, 95% CI, 0.231 to 1.401; for SA patients OR, 0.441, 95% CI, 0.169 to 1.154) did not show any difference between AMI, UA and, SA patients and the control subjects. CONCLUSION: The distribution of P2Y1 polymorphisms did not show any association with ischemic vascular disease.

Effects of P2Y1 receptor on glial fibrillary acidic protein and glial cell line-derived neurotrophic factor production of astrocytes under ischemic condition and the related signaling pathways / 神经科学通报·英文版

<p><b>OBJECTIVE</b>The present study aimed to explore the role of P2Y(1) receptor in glial fibrillary acidic protein (GFAP) production and glial cell line-derived neurotrophic factor (GDNF) secretion of astrocytes under ischemic insult and the related signaling pathways.</p><p><b>METHODS</b>Using transient right middle cerebral artery occlusion (tMCAO) and oxygen-glucose-serum deprivation for 2 h as the model of ischemic injury in vivo and in vitro, immunofluorescence, quantitative real-time reverse transcription-polymerase chain reaction (RT-PCR), Western blotting, enzyme linked immunosorbent assay (ELISA) were used to investigate location of P2Y(1) receptor and GDNF, the expression of GFAP and GDNF, and the changes of signaling molecules.</p><p><b>RESULTS</b>Blockage of P2Y(1) receptor with the selective antagonist N(6)-methyl-2'-deoxyadenosine 3',5'-bisphosphate diammonium (MRS2179) reduced GFAP production and increased GDNF production in the antagonist group as compared with simple ischemic group both in vivo and in vitro. Oxygen-glucose-serum deprivation and blockage of P2Y(1) receptor caused elevation of phosphorylated Akt and cAMP response element binding protein (CREB), and reduction of phosphorylated Janus kinase2 (JAK2) and signal transducer and activator of transcription3 (STAT3, Ser727). After blockage of P2Y(1) receptor and deprivation of oxygen-glucose-serum, AG490 (inhibitor of JAK2) reduced phosphorylation of STAT3 (Ser727) as well as expression of GFAP; LY294002, an inhibitor of phosphatidylinositol 3-kinase (PI3-K), decreased phosphorylation of Akt and CREB; the inhibitor of mitogen-activated protein kinase kinase1/2 (MEK1/2) U0126, an important molecule of Ras/extracellular signal-regulated kinase (ERK) signaling pathway, decreased the phosphorylation of JAK2, STAT3 (Ser727), Akt and CREB.</p><p><b>CONCLUSION</b>These results suggest that P2Y(1) receptor plays a role in the production of GFAP and GDNF in astrocytes under transient ischemic condition and the related signaling pathways may be JAK2/STAT3 and PI3-K/Akt/CREB, respectively, and that crosstalk probably exists between them.</p>

Activation of nicotinic acetylcholine receptor prevents the production of reactive oxygen species in fibrillar beta amyloid peptide (1-42)-stimulated microglia

Recent studies have reported that the "cholinergic anti-inflammatory pathway" regulates peripheral inflammatory responses via alpha7 nicotinic acetylcholine receptors (alpha7 nAChRs) and that acetylcholine and nicotine regulate the expression of proinflammatory mediators such as TNF-alpha and prostaglandin E2 in microglial cultures. In a previous study we showed that ATP released by beta-amyloid-stimulated microglia induced reactive oxygen species (ROS) production, in a process involving the P2X7 receptor (P2X7R), in an autocrine fashion. These observations led us to investigate whether stimulation by nicotine could regulate fibrillar beta amyloid peptide (1-42) (fA beta(1-42))-induced ROS production by modulating ATP efflux-mediated Ca2+ influx through P2X7R. Nicotine inhibited ROS generation in fA beta(1-42)-stimulated microglial cells, and this inhibition was blocked by mecamylamine, a non-selective nAChR antagonist, and a-bungarotoxin, a selective alpha7 nAChR antagonist. Nicotine inhibited NADPH oxidase activation and completely blocked Ca2+ influx in fA beta(1-42)-stimulated microglia. Moreover, ATP release from fA beta(1-42)-stimulated microglia was significantly suppressed by nicotine treatment. In contrast, nicotine did not inhibit 2',3'-O-(4-benzoyl)-benzoyl ATP (BzATP)-induced Ca2+ influx, but inhibited ROS generation in BzATP-stimulated microglia, indicating an inhibitory effect of nicotine on a signaling process downstream of P2X7R. Taken together, these results suggest that the inhibitory effect of nicotine on ROS production in fA beta(1-42)-stimulated microglia is mediated by indirect blockage of ATP release and by directly altering the signaling process downstream from P2X7R.

Cross talk between P2 purinergic receptors modulates extracellular ATP-mediated interleukin-10 production in rat microglial cells

Previously we demonstrated that ATP released from LPS-activated microglia induced IL-10 expression in a process involving P2 receptors, in an autocrine fashion. Therefore, in the present study we sought to determine which subtype of P2 receptor was responsible for the modulation of IL-10 expression in ATP-stimulated microglia. We found that the patterns of IL-10 production were dose-dependent (1, 10, 100, 1,000 micrometer) and bell-shaped. The concentrations of ATP, ATP-gammaS, ADP, and ADP-beta S that showed maximal IL-10 release were 100, 10, 100, and 100 micrometer respectively. The rank order of agonist potency for IL-10 production was 2'-3'-O-(4-benzoyl)-benzoyl ATP (BzATP) = dATP > 2-methylthio-ADP (2-meSADP). On the other hand, 2-methylthio-ATP (2-meSATP), alpha,beta-methylene ATP (alpha,beta-meATP), UTP, and UDP did not induce the release of IL-10 from microglia. Further, we obtained evidence of crosstalk between P2 receptors, in a situation where intracellular Ca2+ release and/or cAMP-activated PKA were the main contributors to extracellular ATP-(or ADP)-mediated IL-10 expression, and IL-10 production was down- regulated by either MRS2179 (a P2Y1 antagonist) or 5'-AMPS (a P2Y11 antagonist), indicating that both the P2Y1 and P2Y11 receptors are major receptors involved in IL-10 expression. In addition, we found that inhibition of IL-10 production by high concentrations of ATP-gammaS (100 micrometer) was restored by TNP-ATP (an antagonist of the P2X1, P2X3, and P2X4 receptors), and that IL-10 production by 2-meSADP was restored by 2meSAMP (a P2Y12 receptor antagonist) or pertusis toxin (PTX; a Gi protein inhibitor), indicating that the P2X1, P2X3, P2X4 receptor group, or the P2Y12 receptor, negatively modulate the P2Y11 receptor or the P2Y1 receptor, respectively.

ATP released from beta-amyloid-stimulated microglia induces reactive oxygen species production in an autocrine fashion

Present study demonstrated that fibrillar beta-amyloid peptide (fAbeta(1-42)) induced ATP release, which in turn activated NADPH oxidase via the P2X(7) receptor (P2X(7)R). Reactive oxygen species (ROS) production in fAbeta(1-42)-treated microglia appeared to require Ca2+ influx from extracellular sources, because ROS generation was abolished to control levels in the absence of extracellular Ca2+. Considering previous observation of superoxide generation by Ca2+ influx through P2X(7)R in microglia, we hypothesized that ROS production in fAbeta-stimulated microglia might be mediated by ATP released from the microglia. We therefore examined whether fAbeta(1-42)-induced Ca2+ influx was mediated through P2X(7)R activation. In serial experiments, we found that microglial pretreatment with the P2X(7)R antagonists Pyridoxal-phosphate-6-azophenyl-2',4'- disulfonate (100 micrometer) or oxidized ATP (100 micrometer) inhibited fAbeta-induced Ca2+ influx and reduced ROS generation to basal levels. Furthermore, ATP efflux from fAbeta(1-42)-stimulated microglia was observed, and apyrase treatment decreased the generation of ROS. These findings provide conclusive evidence that fAbeta-stimulated ROS generation in microglial cells is regulated by ATP released from the microglia in an autocrine manner.

Electrophysiological characteristic of ATP-activated currents of trigeminal ganglion neurons with different diameter in rat / 中国应用生理学杂志

<p><b>AIM</b>To explore the characteristic of ATP-activated current in trigeminal ganglion (TG) neurons of rat.</p><p><b>METHODS</b>Whole-cell patch-clamp was performed.</p><p><b>RESULTS</b>(1) The majority (92.1%) of TG neurons responded to ATP applied externally with inward currents. We recorded three distinct ATP-activated currents: fast, slow and intermediate, which were concentration-dependent. (2) In general, the fast ATP-activated currents were distributed mainly in small-diameter TG neurons, the slow ATP-activated currents were distributed mainly in large-diameter TG neurons, and the intermediate ATP-activated currents were distributed mainly in intermediate-diameter TG neurons. (3) The time course of rising phase from 10% to 90% of the three distinct ATP-activated currents were as follows: fast: (33.6 +/- 4.5) ms; intermediate: (62.2 +/- 9.9) ms; slow: (302.1 +/- 62.0) ms, and that of desensitizing phase were (399.4 +/- 58.2) ms (fast), and > 500 ms (slow) respectively. (4) From the current-voltage relationship curves, it can be seen that the reversal potential values of the three distinct ATP-activated currents were the same, all being 0-5mV. And they all were characterized by inward rectification. (5) The dose-response curve for fast ATP-activated current shifted downwards as compared with the intermediate ATP-activated current, and that for the slow ATP-activated current shifted upwards.</p><p><b>CONCLUSION</b>The EC50s of the three curves tended to be identical. The results suggested that three kinds of distinct ATP-activated currents could be mediated by various subtypes of P2X receptors assembled by different subunits, and the subtypes existed in TG neurons of different diameters and transmit different information.</p>