Research progress of purinergic signaling in dry age-related macular degeneration / 中华实验眼科杂志

Age-related macular degeneration (AMD) is one of the major causes of visual loss in people over 65 years of age.There is limited treatment for dry AMD, because of its complex mechanism.Purinergic signaling has the functions of signal transduction and neuro-modulation, participates in the development of dry AMD by regulating retinal cell death, microglial activity, inflammation, pathological deposit formation and retinal edema etc.In this study, we discussed the role and mechanisms involved in dry AMD by introducing the components of the purinergic signaling pathway, and further summarized the regulation of key processes in the pathogenesis of AMD in order to provide a reference for clinical research.

Interactions of purinergic receptors in treating neuropathic pain using electroacupuncture / 中华物理医学与康复杂志

Objective To elucidate the mechanism underlying eletroacupuncture's (EA's) amply-documented analgesic effect.To observe its effect on the pain threshold and on the expression of P2X4 receptor and microglia activation in the spinal cords of rats with neuropathic pain.To demonstrate whether or not interfering with A1 receptors and P2X4 receptors at the same time could enhance the analgesic effect.Methods A total of 40 SpragueDawley rats weighing 150 to 180 g were randomly divided into a sham group,a CCI group,an EA group,a 2-chloroN(6)-cyclopentyladenosine (CCPA) group and a CCPA+EA group,each of 8.Chronic constriction injury (CCI)was induced successfully in the rats of all groups except the sham group.Five days later,EA and 20 μL injections of 0.1 mm/L CCPA were applied to the rat analogues of the Zusanli (ST36) and Yanglingquan (GB34) acupoints once a day for 15 days for the rats in the appropriate groups.The mechanical withdrawal threshold (MWT) and the thermal withdrawal latency (TWL) were measured before the CCI operation and 20 days afterward.L4-L6 spinal cord tissue was then resected and the fluorescence intensity of P2X4 and OX42 receptors was detected using double label immunohistochemical staining.The correlation between the mean fluorescence intensity and the pain threshold gap was analyzed.Results The average MWT and TWL of the CCI group were significantly lower than in the other four groups.The expression of P2X4 receptor and OX42 in the spinal cord increased significantly in the CCI group compared to the other four groups.There was significant correlation between the mean fluorescence intensity of P2X4 and OX42 receptors and the gap in pain threshold,with correlation coefficients of 0.907 and 0.717 respectively.Conclusion P2X4 receptor and microglia activation might be involved in the development of neuropathic pain.CCPA and EA can inhibit the activation of microglia and reduce the activity of P2X4 receptors.The interaction between A1 receptors and P2X4 receptors can strengthen the analgesic effect of EA.

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

Function of purinergic receptorsin communication between neurons and glial cells / 中国药理学通报

The function of the nervous system is largely determined by the communication between neurons and glial cells.The interaction of complex signaling pathways between neurons and glial cells involves in a variety of signaling molecules.Purines and the purinergic receptors play a crucial role in the process of the interaction.For a long time, the study on the central nervous system is mainly focused on neurons, while glial cells are mainly used as support cells or in response to brain injury to provide a guiding role.The latest research shows that glial cells play an important role in the occurrence and development of nervous system diseases.We will summarize the function of purinergic receptors in the interaction of neurons and glial cells and in neurological diseases.

Effect of Sinomenine on Expression of Purinergic Receptors A2A and P2X7 in Mouse Model and In-vitro Macrophages Stimulated by Lipopolysaccharide / 广州中医药大学学报

Objective To investigate the effect of sinomenine on the purinergic receptors A2A and P2X7 in endotoxemia mouse model and RAW264.7 macrophage model stimulated by lipopolysaccharide(LPS). Methods BALB/c mice were randomly divided into blank control group, model group and sinomenine group. Thirty minutes after the rats of sinomenine group were pretreated with intraperitoneal injection of sinomenine (40, 80, 160 mg/kg), the mice were given intraperitoneal injection of 15 mg/kg LPS to induce endotoxemia model. The serum levels of tumor necrosis factor-alpha(TNF-α) and interleukin-6(IL-6) were measured by enzyme-linked immunosorbent assay (ELISA). The expression levels of purinergic receptor A2A and P2X7 in the liver and spleen were detected by reverse transcription-polymerase chain reaction(RT-PCR). RAW264.7 macrophages were divided into blank control group, LPS group and sinomenine group. Sinomenine group was firstly treated with sinomenine(300μmol/L) for 2 h, and then LPS group and sinomenine group were treated with LPS (100 ng/mL) for another 8 hours. TNF-α in the cell supernatant was measured by ELISA, and the expression levels of A2A and P2X7 in RAW264.7 cells were detected by RT-PCR. Results Stimulation with LPS could induce the increase of the mouse serum levels of TNF-α and IL-6 as well as the expression of A2A and P2X7 in mouse liver and spleen, and sinomenine had a counteraction on the above indexes(P<0.05) . In-vitro stimulation with LPS could induce the increase of the content of TNF-α and the expression of A2A and P2X7 in RAW264.7 cells , and sinomenine decreased TNF-α content and P2X7 expression (P<0.05) , but had an effect on enhancing A2A expression. Conclusion Sinomenine suppresses the expression of purinergic receptor P2X7 in mouse spleen and liver as well as in RAW264.7 macrophages, but its effect on the expression of A2A in various tissues and cells varies, whose related mechanism is needed further study.

Satellite glial cells in sensory ganglia: its role in pain / Células gliais satélite de gânglios sensitivos: o seu papel na dor / Células gliales satélite de ganglios sensoriales: su papel en el dolor

BACKGROUND AND OBJECTIVES: Satellite glial cells in sensory ganglia are a recent subject of research in the field of pain and a possible therapeutic target in the future. Therefore, the aim of this study was to summarize some of the important physiological and morphological characteristics of these cells and gather the most relevant scientific evidence about its possible role in the development of chronic pain. CONTENT: In the sensory ganglia, each neuronal body is surrounded by satellite glial cells forming distinct functional units. This close relationship enables bidirectional communication via a paracrine signaling between those two cell types. There is a growing body of evidence that glial satellite cells undergo structural and biochemical changes after nerve injury, which influence neuronal excitability and consequently the development and/or maintenance of pain in different animal models of chronic pain. CONCLUSIONS: Satellite glial cells are important in the establishment of physiological pain, in addition to being a potential target for the development of new pain treatments. .

JUSTIFICATIVA E OBJETIVOS: As células gliais satélite de gânglios sensitivos são um objeto recente de pesquisa na área da dor e um possível alvo terapêutico no futuro. Assim, este trabalho tem como objetivo resumir algumas das características morfológicas e fisiológicas mais importantes destas células e reunir as evidências científicas mais relevantes acerca do seu possível papel no desenvolvimento da dor crônica. CONTEÚDO: Nos gânglios sensitivos cada corpo neuronial é envolvido por células gliais satélite, formando unidades funcionais distintas. Esta íntima relação possibilita a comunicação bidirecional, através de uma sinalização parácrina, entre estes dois tipos de células. Existe um número crescente de evidências de que as células gliais satélite sofrem alterações estruturais e bioquímicas, após lesão nervosa, que influenciam a excitabilidade neuronial e consequentemente o desenvolvimento e/ou manutenção da dor, em diferentes modelos animais de dor crônica. CONCLUSÕES: As células gliais satélite são importantes no estabelecimento da dor não fisiológica e constituem um alvo potencial para o desenvolvimento de novos tratamentos da dor. .

JUSTIFICACIÓN Y OBJETIVOS: Las células gliales satélite de ganglios sensoriales son un objeto reciente de investigación en el área del dolor y un posible objeto terapéutico en el futuro. Por tanto, este trabajo intenta resumir algunas de las características morfológicas y fisiológicas más importantes de estas células y reunir las evidencias científicas más relevantes acerca de su posible papel en el desarrollo del dolor crónico. CONTENIDO: En los ganglios sensoriales cada cuerpo neuronal está envuelto por células gliales satélite, formando unidades funcionales distintas. Esta íntima relación posibilita la comunicación bidireccional a través de una señalización paracrina entre esos 2 tipos de células. Existe un número creciente de evidencias de que las células gliales satélite sufren alteraciones estructurales y bioquímicas después de la lesión nerviosa que influyen en la excitabilidad neuronal y por ende en el desarrollo y/o en el mantenimiento del dolor en diferentes modelos animales de dolor crónico. CONCLUSIONES: Las células gliales satélite son importantes en el establecimiento del dolor no fisiológico y son un potencial objetivo para el desarrollo de nuevos tratamientos del dolor. .

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

Drug therapy of overactive bladder - What is coming next?

After the approval and introduction of mirabegron, tadalafil, and botulinum toxin A for treatment of lower urinary tract symptoms/overactive bladder, focus of interest has been on their place in therapy versus the previous gold standard, antimuscarinics. However, since these agents also have limitations there has been increasing interest in what is coming next - what is in the pipeline? Despite progress in our knowledge of different factors involved in both peripheral and central modulation of lower urinary tract dysfunction, there are few innovations in the pipe-line. Most developments concern modifications of existing principles (antimuscarinics, beta3-receptor agonists, botulinum toxin A). However, there are several new and old targets/drugs of potential interest for further development, such as the purinergic and cannabinoid systems and the different members of the transient receptor potential channel family. However, even if there seems to be good rationale for further development of these principles, further exploration of their involvement in lower urinary tract function/dysfunction is necessary.

Expression of P2X7 receptor in endometriosis tissues of patients with ovarian endometriosis / 第二军医大学学报

Objective: To investigate the different expressions of purinergic P2X7 receptor in normal endometrium and ectopic endometrium of patients with endometriosis (EMS), so as to discuss the possible role of P2X7 receptor in the development of EMS. Methods: The tissue samples (ovarian endometriotic cysts) of EMS patients (EMS group, n=54) and normal endometrium tissues from uterine fibroid patients undergoing hysterectomy (control group, n = 40) from Oct. 2011 to Oct. 2012 were retrieved in Changhai Hospital. The expression of P2X7 receptor was detected and compared by immunohistochemistry between the two groups. P2X7 receptor expressions were also compared between patients with different preoperative serum CA125 levels or EMS stage according to intraoperative evaluation by revised American Fertility Society (rAFS) staging. Results: (1) The positive rate of P2X7 receptor was 75. 9% (41/54, with 22 weakly positive, 14 positive and 5 strongly positive) in 54 EMS samples, which was significantly higher than that in normal endometrial tissues (7. 5%, 3/40, all weakly positive)(χ2 = 43. 21, P<0. 05). P2X7 receptor expression intensities were also significantly different between the two groups(Z= - 7. 318, P<0. 05). (2) P2X7 receptor expressions in EMS patients with serum CA125 ≥50 U/mL or of III-IV stage (rAFS) were significantly stronger than those with serum CA125 < 50 U/mL (Z= - 2.642. P<0. 05) or of I II stage (Z= - 3. 815, P<0. 001). Conclusion: P2X7 receptor is highly expressed in the ectopic endometrium tissue, and the expression is associated with the pre-operation serum CA125 level and severity of disease, suggesting that P2X7 receptor may be involved in the development of endometriosis.

Señales purinérgicas / Purinergic signals

En la última década se ha aportado clara evidencia de que tanto nucleósidos como nucleótidos de adenina y uridina pueden funcionar como factores de señalización extracelular. Su acción es mediada por dos tipos principales de receptores de superficie denominados purinérgicos. Los receptores P1 se activan por adenosina, y son todos metabotrópicos, mientras que los receptores de nucleótidos (ATP, ADP, UTP y UDP) y nucleótidos-azúcares (UDP-glucosa y UDP-galactosa) pueden ser metabotrópicos (P2Y) o ionotrópicos (P2X). La importancia y complejidad de este sistema de señalización se evidencia por la diversidad de mecanismos de liberación de nucleótidos al medio extracelular y por la distribución ubicua de varios grupos de ectonucleotidasas capaces de catalizar la degradación y conversión de nucleótidos. Hasta el momento se han descrito y clonado una veintena de estos receptores que modulan una variedad de respuestas, como el impulso nervioso, la respuesta inflamatoria, la secreción de insulina, la regulación del tono vascular y la percepción del dolor. En la presente revisión se describen las características estructurales y farmacológicas de los receptores purinérgicos y se analiza la interacción dinámica entre estos receptores, los nucleósidos y nucleótidos, y las ectonucleotidasas, con especial atención a la dinámica de la agregación plaquetaria, la respuesta inmune y la hidratación de las mucosas respiratorias.

In the last decade evidence accumulated that nucleosides and nucleotides of both uridine and adenine can act as extracellular signaling factors. Their action is mediated by two main types of surface receptors commonly known as purinergic. P1 receptors are metabotropic and activated by adenosine, whereas receptors for nucleotides (ATP, ADP, UTP and UDP) and nucleotide-sugars (UDP-glucose and UDP-galactose) can be either metabotropic (P2Y) or ionotropic (P2X). The importance and complexity of this signaling system is evidenced by various mechanisms of nucleotide release, as well as by the ibiquitous distribution of various types of ectonucleotidases which catalyze and convert extracellular nucleotides. Up to now about twenty receptors have been cloned and found to modulate the nerve impulse, inflammatory response, insuline secretion, the regulation of the vascular tone and nociception, among other processes. In the present review we describe the main structural and pharmacological features of purinergic receptors, and analyze how the dynamic interaction between these receptors, nucleotides and nucleosides, and ectonucleotidases modulate several biological responses. Particular focus is given to platelet aggregation and thrombus formation, the immune response and the hydration of the mucosal linings of the respiratory tract.

Antidipsogenic effects of central adenosine-5'-triphosphate

Besides other physiological functions, adenosine-5'-triphosphate (ATP) is also a neurotransmitter that acts on purinergic receptors. In spite of the presence of purinergic receptors in forebrain areas involved with fluid-electrolyte balance, the effect of ATP on water intake has not been investigated. Therefore, we studied the effects of intracerebroventricular (icv) injections of ATP (100, 200 and 300 nmol/µL) alone or combined with DPCPX or PPADS (P1 and P2 purinergic antagonists, respectively, 25 nmol/µL) on water intake induced by water deprivation. In addition, the effect of icv ATP was also tested on water intake induced by intragastric load of 12 percent NaCl (2 mL/rat), acute treatment with the diuretic/natriuretic furosemide (20 mg/kg), icv angiotensin II (50 ng/µL) or icv carbachol (a cholinergic agonist, 4 nmol/µL), on sodium depletion-induced 1.8 percent NaCl intake, and on food intake induced by food deprivation. Male Holtzman rats (280-320 g, N = 7-11) had cannulas implanted into the lateral ventricle. Icv ATP (300 nmol/µL) reduced water intake induced by water deprivation (13.1 ± 1.9 vs saline: 19.0 ± 1.4 mL/2 h; P < 0.05), an effect blocked by pre-treatment with PPADS, but not DPCPX. Icv ATP also reduced water intake induced by NaCl intragastric load (5.6 ± 0.9 vs saline: 10.3 ± 1.4 mL/2 h; P < 0.05), acute furosemide treatment (0.5 ± 0.2 vs saline: 2.3 ± 0.6 mL/15 min; P < 0.05), and icv angiotensin II (2.2 ± 0.8 vs saline: 10.4 ± 2.0 mL/2 h; P < 0.05), without changing icv carbachol-induced water intake, sodium depletion-induced 1.8 percent NaCl intake and food deprivation-induced food intake. These data suggest that central ATP, acting on purinergic P2 receptors, reduces water intake induced by intracellular and extracellular dehydration.

Modulators of Ion Transport in Nasal Polyps: An in situ Measurement of Short-Circuit Current

OBJECTIVES: To examine possible modulators of the ion transport through the apical membrane of the nasal polyps. METHODS: The study was conducted using the freshly-excised nasal polyps from the patients with chronic sinusitis. A voltage-sensitive vibrating probe technique was introduced to monitor the short-circuit current across the apical membrane of the polyp at 37degrees C. RESULTS: In the presence of amiloride, Adenosine 5'-triphosphate induced 4,4'-Diisothiocyanatostilbene-2,2'-disulfonic acidsensitive chloride current. Uridine 5'-diphosphate was less potent than Uridine 5'-triphosphate, and adenosine increased chloride secretion, which was blocked by the antagonist, 8-(p-sulfophenyl) theophylline on adenosine receptor. Based on the pharmacologic profiles, multiple purinergic receptors, including P2Y(2), P2Y(6), and P1 receptors, were functionally expressed. However, P2X receptor agonists (alpha,beta-methyleneadenosine 5'-triphosphate and 2'- & 3'-O-[4-benzoyl-benzoyl] adenosine 5'-triphosphate), Cystic fibrosis conductance regulator (CFTR) activator (genistein), nitric oxide substrate (L-arginine), and nitric oxide donor (sodium nitroprusside) had no significant effect on the short circuit current. CONCLUSION: Among tested drugs, P2Y receptor agonists were major modulators of ion transport in nasal polyps in situ.

The involvement of purinergic receptors in the kidney physiological and pathophysiological implications / O envolvimento de receptores purinérgicos no rim implicações fisiológicas e fisiopatológicas

The studies on the purinergic system in the kidney clearly showed its role on the renal hemodynamics, glomerular filtration and tubular function. The effectsof purinergic agonists on the mechanisms of tubuloglomerular feedback, and tubular transport of water and solutes, are well defined. In addition, severalstudies have documented the role of adenosine and specific ATP receptors on the processes of renal diseases, with special interest on the ischemiareperfusioninjury, renal cystic disease, glomerular and tubulointerstitial diseases. Therefore, the purinergic system has become a growing field for researchin renal physiology and pathophysiology, leading to therapeutic possibilities of using specific agonists and antagonists.

Os estudos sobre o sistema purinérgico no rim evidenciaram ao longo dos anos a sua participação na hemodinâmica renal, filtração glomerular e funçãotubular. É bem conhecida a participação de efetores purinérgicos no mecanismo de feedback túbulo-glomerular e transporte tubular de água e solutos.Além disso, vários trabalhos têm mostrado a participação da adenosina e de receptores específicos de ATP em processos de doença renal, com umespecial interesse na lesão da isquemia-reperfusão, doença cística renal, doenças glomerulares e túbulo-intersticiais. Portanto, o sistema purinérgico temse tornado alvo crescente de pesquisa em fisiologia e fisiopatologia renal, voltando-se para as possibilidades terapêuticas no uso de agentes agonistas eantagonistas específicos.

Nucleotide signals in the central nervous system and microglial movements / 中国药理学通报

Microglia cells are immune cells in the central nervous system.When the microenvironment of brain has changed,microglia will respond rapidly.ATP,UTP,or other nucleotide signals released by neurons from damaged site and their metabolites such as ADP,adenosine,UDP and so on will bind with the purinergic receptors on microglia to regulate the morphology and function of microglia,then the microglial cells activated by nucleotide signals are to regulate neural cells by phagocytosis or releasing cytokines.In this article,the function and corresponding mechanisms of nucleotide signals on chemotaxis,phagocytosis,and process retraction are reviewed.

Apoptosis related with extracellular adenosine triphosphate and adenosine and their purinergic receptors / 中国药理学通报

Extracellular adenosine triphosphate (ATP) and adenosine are important signaling molecules in both intracellular and extracellular microenviroments of cells. They exert cytoxic and apoptotic effects in some tissues such as tumor. The proapoptotic mechanisms of adenosine and its receptors are involved in Adenylyl cyclase(AC), cAMP, Ca 2+ , etc. Apoptosis induced by ATP is as sociated with several purinergic receptors including P2X_1, P2X_2, P2X_7, P2Y_1, P2Y_2, et al, it is also involved in FasL/FasR, T cell receptor(TCR), and gene regulations of bcl-2 and bax.

The Effects of Neurotransmitters on the Ion Channels in the Isolated Deiters'Cells of Guinea Pig Cochlea / 대한이비인후과학회지

BACKGROUND AND OBJECTIVES: The supporting cells in the organ of Corti help to maintain the structural integrity of the organ, but it has been suggested that they also actively participate in regulating sound transduction. The existence of neural control was implied by the finding of efferent synapses in Deiters' cells, and the fact that the intracellular Ca2+ concentration was increased by the application of neurotransmitters, such as ATP (adenosine triphosphate) and Ach (acetylcholine), resulting in movement of the phalangeal processes of the Deiters' cells. This study investigated the effects of neurotransmitters on the ion channels in Deiters' cells. MATERIALS AND METHOD: Deiters' cells were isolated from guinea pig organs of Corti using collagenase and pipettes. Whole-cell patch clamps were performed under an inverted microscope and the current was measured with pClamp 8.0.2 software. RESULTS: The resting membrane potential was -21.1+/-3.5 mV. ATP (100 microM) treatment depolarized the potential to -3.1+/-1.1 mV, while the same concentration of Ach had no effect on the resting potential. In the voltage-clamping condition, the holding potential was 0 mV, and then a -80 mV pre-pulse was applied for 500 ms, followed by step pulses from -140 to +10 mV. Under these conditions, 10 microM ATP increased the inward current from -14.9+/-1.9 to -163.5+/-14.9 pA/pF at the maximal stimulus of -140 mV (n=4). In the current-voltage curve, the reversal potential was around -20 mV. Neither Ach nor carbachol induced current responses. The co-application of suramin (30 microM) and ATP (10 microM) suppressed the ATP-induced currents by 50%, and 30 microM of PPADS (pyridoxal-phosphate- 6-azophenyl-2, 4-disulphonic acid) inhibited the current almost to the level of the control. The purinoceptor-agonist, alpha, beta-meATP (alpha, beta-methylene adenosine triphosphate), 30 microM increased the inward current from -16.2+/-2.9 to -27.7+/-3.8 pA/pF, which was much smaller than the ATP-induced change. CONCLUSION: ATP-gated purinergic receptors may play an important role in regulating sound transduction by inducing an inward current and depolarizing the Deiters' cell membrane.