Your browser doesn't support javascript.
Mostrar: 20 | 50 | 100
Resultados 1 - 20 de 960
Filtrar
Mais filtros










Intervalo de ano de publicação
1.
Theriogenology ; 121: 160-167, 2018 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-30165304

RESUMO

Oocyte meiosis is a complex process coordinated by multiple endocrinal and molecular circuits. Recently, N6-methyladenosine (m6A) epigenetic modification on RNA is revealed to be important for meiotic maturation. However, the molecular mechanism of how m6A modification exerts its effect on oocyte maturation is largely unknown. Here, we showed that endogenous m6A writers (Mettl3 and Wtap) and eraser (Fto) elevated their transcript levels during meiotic maturation of pig oocytes. From germinal vesicle (GV) to metaphase II (MII) stages, global m6A level significantly increased, and existed mostly in ooplasm. Methyl donor (betaine, 16 mM) treatment of porcine cumulus-oocyte complexes (COCs) during in vitro maturation (IVM) significantly boosted nucleic acid m6A level within oocytes, but unchanged meiotic process and oocyte subsequent development. By contrast, methylation inhibitor (cycloleucine, 20 mM) reduced nucleic acid m6A level, and significantly decreased the germinal vesicle breakdown (GVBD) rate, the extrusion rate of the first polar body, and the cleavage and blastocyst rates of parthenotes. In addition, in cycloleucine-treated oocytes Wtap increased but Lin28 decreased their abundances significantly, along with the higher incidence of spindle defects and chromosome misalignment. Furthermore, pT161-CDK1 protein level in pig oocytes was confirmed to be decreased after cycloleucine treatment for 24 h. Taken together, chemical induced reduction of nucleic acid m6A methylation during pig oocyte meiosis could impair meiotic maturation and subsequent development potency, possibly through down-regulating pluripotency marker Lin28 mRNA abundance and disturbing MPF-regulated chromosome/spindle organization.


Assuntos
Metilação de DNA , Oócitos/citologia , Animais , Betaína/farmacologia , Proteína Quinase CDC2/genética , Proteína Quinase CDC2/metabolismo , Cicloleucina/farmacologia , Meiose/genética , Oócitos/efeitos dos fármacos , Oócitos/crescimento & desenvolvimento , Suínos/embriologia
2.
J Cell Biochem ; 119(7): 5676-5685, 2018 07.
Artigo em Inglês | MEDLINE | ID: mdl-29384213

RESUMO

Fat mass and obesity-associated protein (FTO) is a RNA demethylase, whether FTO regulates fat metabolism through its demethylation is unclear. The results of this study confirmed that N6-methyladenosine (m6 A) is associated with fat accumulation both in vivo and in vitro. The data showed that FTO down-regulated m6 A levels, decreased mitochondrial content, and increased triglyceride (TG) deposition. However, an FTO (R316A) mutant lacking demethylation activity could not regulate mitochondria and TG content, indicating that FTO affects mitochondrial content and fat metabolism by modulating m6 A levels in hepatocytes. In addition, the regulatory roles of cycloleucine (methylation inhibitor) and betaine (methyl donor) could regulate m6 A levels and fat deposition. This work clarified that the demethylation function of FTO plays an essential role in the fat metabolism of hepatocytes and links the epigenetic modification of RNA with fat deposition, thereby providing a new target (m6 A) for regulation of hepatic fat metabolism.


Assuntos
Dioxigenase FTO Dependente de alfa-Cetoglutarato/metabolismo , Desmetilação/efeitos dos fármacos , Gorduras/metabolismo , Hepatócitos/patologia , Metabolismo dos Lipídeos/efeitos dos fármacos , Mitocôndrias/patologia , RNA/genética , Dioxigenase FTO Dependente de alfa-Cetoglutarato/química , Dioxigenase FTO Dependente de alfa-Cetoglutarato/genética , Animais , Betaína/farmacologia , Cicloleucina/farmacologia , Epigênese Genética , Células Hep G2 , Hepatócitos/efeitos dos fármacos , Hepatócitos/metabolismo , Humanos , Lipotrópicos/farmacologia , Metilação , Mitocôndrias/efeitos dos fármacos , Mitocôndrias/metabolismo , Conformação Proteica , Suínos
3.
Mol Nutr Food Res ; 61(11)2017 11.
Artigo em Inglês | MEDLINE | ID: mdl-28759161

RESUMO

SCOPE: Serine lies at the central node linking biosynthetic flux from glycolysis to glutathione synthesis and one-carbon metabolic cycle which are closely related to antioxidant capacity. The present study was conducted to determine the effects of serine supplementation on oxidative stress and its relative mechanisms. METHODS AND RESULTS: Diquat treatment was performed to induce oxidative stress in mice and primary hepatocytes. The results showed that hepatic glutathione anti-oxidant systems were impaired and reactive oxygen species and homocysteine were increased in diquat-induced mice and hepatocytes, while such disadvantageous changes were diminished by serine supplementation both in vivo and in vitro. However, when cystathionine ß-synthase expression was inhibited by interference RNA in hepatocytes, the effects of serine supplementation on the improvement of glutathione synthesis and the alleviation of oxidative stress were diminished. Moreover, when hepatocytes were treated with cycloleucine, an inhibitor of methionine adenosyltransferase, the effects of serine supplementation on the improvement of methionine cycle and the alleviation of DNA hypomethylation and oxidative stress were also diminished. CONCLUSION: Our results indicated that serine supplementation alleviated oxidative stress via supporting glutathione synthesis and methionine cycle, mostly by condensing with homocysteine to synthesize cysteine and providing one-carbon units for homocysteine remethylation.


Assuntos
Antioxidantes/uso terapêutico , Suplementos Nutricionais , Glutationa/metabolismo , Hepatócitos/metabolismo , Metionina/metabolismo , Estresse Oxidativo , Serina/uso terapêutico , Animais , Antioxidantes/química , Antioxidantes/metabolismo , Células Cultivadas , Doença Hepática Induzida por Substâncias e Drogas/metabolismo , Doença Hepática Induzida por Substâncias e Drogas/patologia , Doença Hepática Induzida por Substâncias e Drogas/prevenção & controle , Cicloleucina/farmacologia , Cistationina beta-Sintase/antagonistas & inibidores , Cistationina beta-Sintase/genética , Cistationina beta-Sintase/metabolismo , Metilação de DNA/efeitos dos fármacos , Desfolhantes Químicos/antagonistas & inibidores , Desfolhantes Químicos/toxicidade , Diquat/antagonistas & inibidores , Diquat/toxicidade , Inibidores Enzimáticos/farmacologia , Regulação Enzimológica da Expressão Gênica/efeitos dos fármacos , Hepatócitos/efeitos dos fármacos , Hepatócitos/patologia , Homocisteína/metabolismo , Masculino , Metionina Adenosiltransferase/antagonistas & inibidores , Metionina Adenosiltransferase/metabolismo , Camundongos Endogâmicos C57BL , Estresse Oxidativo/efeitos dos fármacos , Interferência de RNA , Distribuição Aleatória , Serina/antagonistas & inibidores , Serina/metabolismo , Organismos Livres de Patógenos Específicos
4.
Biochemistry ; 56(37): 4951-4961, 2017 09 19.
Artigo em Inglês | MEDLINE | ID: mdl-28816437

RESUMO

Potent mechanism-based inactivators can be rationally designed against pyridoxal 5'-phosphate (PLP)-dependent drug targets, such as ornithine aminotransferase (OAT) or γ-aminobutyric acid aminotransferase (GABA-AT). An important challenge, however, is the lack of selectivity toward other PLP-dependent, off-target enzymes, because of similarities in mechanisms of all PLP-dependent aminotransferase reactions. On the basis of complex crystal structures, we investigate the inactivation mechanism of OAT, a hepatocellular carcinoma target, by (1R,3S,4S)-3-amino-4-fluorocyclopentane-1-carboxylic acid (FCP), a known inactivator of GABA-AT. A crystal structure of OAT and FCP showed the formation of a ternary adduct. This adduct can be rationalized as occurring via an enamine mechanism of inactivation, similar to that reported for GABA-AT. However, the crystal structure of an off-target, PLP-dependent enzyme, aspartate aminotransferase (Asp-AT), in complex with FCP, along with the results of attempted inhibition assays, suggests that FCP is not an inactivator of Asp-AT, but rather an alternate substrate. Turnover of FCP by Asp-AT is also supported by high-resolution mass spectrometry. Amid existing difficulties in achieving selectivity of inactivation among a large number of PLP-dependent enzymes, the obtained results provide evidence that a desirable selectivity could be achieved, taking advantage of subtle structural and mechanistic differences between a drug-target enzyme and an off-target enzyme, despite their largely similar substrate binding sites and catalytic mechanisms.


Assuntos
4-Aminobutirato Transaminase/antagonistas & inibidores , Aspartato Aminotransferases/antagonistas & inibidores , Cicloleucina/análogos & derivados , Inibidores Enzimáticos/farmacologia , Modelos Moleculares , Ornitina-Oxo-Ácido Transaminase/antagonistas & inibidores , Fosfato de Piridoxal/metabolismo , 4-Aminobutirato Transaminase/química , 4-Aminobutirato Transaminase/metabolismo , Aspartato Aminotransferases/química , Aspartato Aminotransferases/genética , Aspartato Aminotransferases/metabolismo , Sítios de Ligação , Domínio Catalítico , Cristalografia por Raios X , Cicloleucina/química , Cicloleucina/metabolismo , Cicloleucina/farmacologia , Bases de Dados de Compostos Químicos , Bases de Dados de Proteínas , Inibidores Enzimáticos/química , Inibidores Enzimáticos/metabolismo , Proteínas de Escherichia coli/antagonistas & inibidores , Proteínas de Escherichia coli/química , Proteínas de Escherichia coli/genética , Proteínas de Escherichia coli/metabolismo , Humanos , Ligantes , Conformação Molecular , Ornitina-Oxo-Ácido Transaminase/química , Ornitina-Oxo-Ácido Transaminase/genética , Ornitina-Oxo-Ácido Transaminase/metabolismo , Conformação Proteica , Fosfato de Piridoxal/química , Piridoxamina/química , Piridoxamina/metabolismo , Proteínas Recombinantes/química , Proteínas Recombinantes/metabolismo , Homologia Estrutural de Proteína , Especificidade por Substrato
5.
J Neurosci ; 37(9): 2403-2414, 2017 03 01.
Artigo em Inglês | MEDLINE | ID: mdl-28137973

RESUMO

Cerebral blood flow (CBF) is controlled by arterial blood pressure, arterial CO2, arterial O2, and brain activity and is largely constant in the awake state. Although small changes in arterial CO2 are particularly potent to change CBF (1 mmHg variation in arterial CO2 changes CBF by 3%-4%), the coupling mechanism is incompletely understood. We tested the hypothesis that astrocytic prostaglandin E2 (PgE2) plays a key role for cerebrovascular CO2 reactivity, and that preserved synthesis of glutathione is essential for the full development of this response. We combined two-photon imaging microscopy in brain slices with in vivo work in rats and C57BL/6J mice to examine the hemodynamic responses to CO2 and somatosensory stimulation before and after inhibition of astrocytic glutathione and PgE2 synthesis. We demonstrate that hypercapnia (increased CO2) evokes an increase in astrocyte [Ca2+]i and stimulates COX-1 activity. The enzyme downstream of COX-1 that synthesizes PgE2 (microsomal prostaglandin E synthase-1) depends critically for its vasodilator activity on the level of glutathione in the brain. We show that, when glutathione levels are reduced, astrocyte calcium-evoked release of PgE2 is decreased and vasodilation triggered by increased astrocyte [Ca2+]iin vitro and by hypercapnia in vivo is inhibited. Astrocyte synthetic pathways, dependent on glutathione, are involved in cerebrovascular reactivity to CO2 Reductions in glutathione levels in aging, stroke, or schizophrenia could lead to dysfunctional regulation of CBF and subsequent neuronal damage.SIGNIFICANCE STATEMENT Neuronal activity leads to the generation of CO2, which has previously been shown to evoke cerebral blood flow (CBF) increases via the release of the vasodilator PgE2 We demonstrate that hypercapnia (increased CO2) evokes increases in astrocyte calcium signaling, which in turn stimulates COX-1 activity and generates downstream PgE2 production. We demonstrate that astrocyte calcium-evoked production of the vasodilator PgE2 is critically dependent on brain levels of the antioxidant glutathione. These data suggest a novel role for astrocytes in the regulation of CO2-evoked CBF responses. Furthermore, these results suggest that depleted glutathione levels, which occur in aging and stroke, will give rise to dysfunctional CBF regulation and may result in subsequent neuronal damage.


Assuntos
Astrócitos/metabolismo , Hipocampo/patologia , Hipercapnia/patologia , Agonistas de Receptores Adrenérgicos alfa 2/farmacologia , Agonistas alfa-Adrenérgicos/farmacologia , Animais , Animais Recém-Nascidos , Dióxido de Carbono/metabolismo , Dióxido de Carbono/farmacologia , Circulação Cerebrovascular/efeitos dos fármacos , Clonidina/farmacologia , Cicloleucina/análogos & derivados , Cicloleucina/farmacologia , Ciclo-Oxigenase 1/metabolismo , Dinoprostona/metabolismo , Feminino , Proteína Glial Fibrilar Ácida/metabolismo , Glutationa/metabolismo , Técnicas In Vitro , Masculino , Proteínas de Membrana/metabolismo , Camundongos , Camundongos Endogâmicos C57BL , Fármacos Neuroprotetores/farmacologia , Norepinefrina/farmacologia , Ratos , Ratos Wistar , Vibrissas/inervação
6.
Biomed Res Int ; 2016: 8178162, 2016.
Artigo em Inglês | MEDLINE | ID: mdl-27413752

RESUMO

Calcium-imaging techniques were used to determine if mouse retinal astrocytes in situ respond to agonists of ionotropic (α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid, AMPA; N-methyl-D-aspartate, NMDA) and metabotropic (S-3,5-dihydroxyphenylglycine, DHPG; trans-1-amino-1,3-cyclopentanedicarboxylic acid, ACPD) glutamate receptors. In most cases we found no evidence that retinal astrocyte intracellular calcium ion concentration ([Ca(2+)]i) increased in response to these glutamate agonists. The one exception was AMPA that increased [Ca(2+)]i in some, but not all, mouse retinal astrocytes in situ. However, AMPA did not increase [Ca(2+)]i in mouse retinal astrocytes in vitro, suggesting that the effect of AMPA in situ may be indirect.


Assuntos
Astrócitos/metabolismo , Cálcio/metabolismo , Agonistas de Aminoácidos Excitatórios/farmacologia , Receptores de Glutamato/metabolismo , Retina/citologia , Animais , Astrócitos/efeitos dos fármacos , Cicloleucina/análogos & derivados , Cicloleucina/farmacologia , Fura-2/metabolismo , Metoxi-Hidroxifenilglicol/análogos & derivados , Metoxi-Hidroxifenilglicol/farmacologia , Camundongos Endogâmicos C57BL , N-Metilaspartato/farmacologia , Ácido alfa-Amino-3-hidroxi-5-metil-4-isoxazol Propiônico/farmacologia
7.
Neurosci Lett ; 618: 152-158, 2016 Apr 08.
Artigo em Inglês | MEDLINE | ID: mdl-26957228

RESUMO

Activation of the N-methyl-d-aspartate receptor (NMDAR) in dorsal horn neurons is recognized as a fundamental mechanism of central sensitization and pathologic pain. This study assessed the influence of dopaminergic, D1-like receptor-mediated input to the spinal dorsal horn on NMDAR function. Spinal superfusion with selective NMDAR agonist cis-ACPD significantly increased C-fiber-evoked field potentials in rats subjected to spinal nerve ligation (SNL), but not in sham-operated rats. Simultaneous application of D1LR antagonist SCH 23390 dramatically reduced hyperexcitability induced by cis-ACPD. Furthermore, cis-ACPD-induced hyperexcitability seen in nerve-ligated rats could be mimicked in unin-jured rats during stimulation of D1LRs by agonist SKF 38393 at subthreshold concentration. Phosphorylation of NMDAR subunit NR1 at serine 889 at postsynaptic sites was found to be increased in dorsal horn neurons 90 min after SNL, as assessed by increased co-localization with postsynaptic marker PSD-95. Increased NR1 phosphorylation was attenuated in the presence of SCH 23390 in the spinal superfusate. The present results support that D1LRs regulate most basic determinants of NMDAR function in dorsal horn neurons, suggesting a potential mechanism whereby dopaminergic input to the dorsal horn can modulate central sensitization and pathologic pain.


Assuntos
Receptores de Dopamina D1/metabolismo , Receptores de N-Metil-D-Aspartato/metabolismo , Serina/metabolismo , Medula Espinal/fisiopatologia , Animais , Cicloleucina/análogos & derivados , Cicloleucina/farmacologia , Potenciais Evocados , Masculino , Fibras Nervosas Amielínicas/fisiologia , Neuralgia/metabolismo , Neuralgia/fisiopatologia , Neurônios/fisiologia , Fosforilação , Subunidades Proteicas/agonistas , Subunidades Proteicas/metabolismo , Ratos Sprague-Dawley , Receptores de Dopamina D1/antagonistas & inibidores , Receptores de N-Metil-D-Aspartato/agonistas , Nervo Isquiático/lesões , Medula Espinal/efeitos dos fármacos , Corno Dorsal da Medula Espinal/efeitos dos fármacos , Corno Dorsal da Medula Espinal/fisiopatologia
8.
Biochem Biophys Res Commun ; 459(2): 201-207, 2015 Apr 03.
Artigo em Inglês | MEDLINE | ID: mdl-25725156

RESUMO

Fat Mass and Obesity-associated protein (FTO), associated with obesity, is proved to demethylate N6-methyladenosine (m(6)A), which raises questions regarding whether m(6)A plays vital roles in adipogenesis. To prove this, overexpression and knockdown of FTO and METTL3, as well as the chemical treatment in procine adipocytes were conducted. The results showed FTO negatively regulated m(6)A levels and positively regulated adipogenesis, while METTL3 positively correlated with m(6)A levels and negatively with adipogenesis. To remove the potential effect of FTO and METTL3 gene, chemical reagents of methylation inhibitor cycloleucine and methyl donor betaine were used to test the regulation effect of m(6)A on adipogenesis. The results showed the inverse effect of m(6)A on lipid accumulation in porcine adipocytes. These findings provide compelling evidence that m(6)A plays a critical role in the regulation of adipogenesis.


Assuntos
Adenosina/análogos & derivados , Adipócitos/metabolismo , Adipogenia/genética , Adipogenia/fisiologia , RNA Mensageiro/genética , RNA Mensageiro/metabolismo , Adenosina/química , Adenosina/metabolismo , Adipócitos/efeitos dos fármacos , Adipogenia/efeitos dos fármacos , Animais , Betaína/farmacologia , Células Cultivadas , Cicloleucina/farmacologia , Regulação para Baixo , Técnicas de Silenciamento de Genes , Metabolismo dos Lipídeos , Metilação , Metiltransferases/antagonistas & inibidores , Metiltransferases/genética , Metiltransferases/metabolismo , RNA Mensageiro/química , Suínos
9.
Neuropharmacology ; 79: 59-65, 2014 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-24219858

RESUMO

Metabotropic glutamate receptors (mGluRs) have been popular drug targets for a variety of central nervous system (CNS) disease models, ranging from seizures to schizophrenia. The current study aimed to determine whether mGluRs participate in lateral hypothalamic (LH) stimulation of feeding. To this end, we used satiated adult male Sprague-Dawley rats stereotaxically implanted with indwelling bilateral LH guide cannulas to determine if injection of (1S,3R)-1-aminocyclopentane-1,3-dicarboxylic acid (ACPD), a broad mGluR group I and II agonist, would elicit feeding. Administration of 100 nmol ACPD induced feeding with a short latency. Similarly, unilateral LH injection of the selective mGluR group I agonist (S)-3,5-dihydroxyphenylglycine (DHPG) elicited significant feeding beginning 60 min postinjection and continuing until 4 h postinjection. Administration of the mGluR5 agonist, (RS)-2-chloro-5-hydroxyphenylglycine (CHPG) produced a smaller delayed feeding response. These delayed but prolonged eating responses suggest that activation of LH mGluR1 and/or mGluR5 might be sufficient to elicit feeding. To determine which subtypes were involved, LH DHPG injections were preceded by LH injection of either the group I antagonist n-phenyl-7-(hydroxyimino)cyclopropa[b]chromen-1a-carboxamide (PHCCC), the mGluR1 antagonist 6-amino-n-cyclohexyl-n,3-dimethylthiazolo[3,2-a]benzimi dazole-2-carboxamide hydrochloride (YM-298198) or the mGluR5 antagonist 3-((2-methyl-4-thiazolyl)ethynyl)pyridine (MTEP), and food intake was measured. PHCCC blocked DHPG-elicited feeding, and each of the other antagonists produced significant feeding suppression. These findings suggest roles for mGluR1 and/or mGluR5 in lateral hypothalamic circuits capable of stimulating feeding behavior.


Assuntos
Ingestão de Alimentos/efeitos dos fármacos , Agonistas de Aminoácidos Excitatórios/farmacologia , Antagonistas de Aminoácidos Excitatórios/farmacologia , Hipotálamo/efeitos dos fármacos , Receptor de Glutamato Metabotrópico 5/metabolismo , Receptores de Glutamato Metabotrópico/metabolismo , Animais , Benzimidazóis/farmacologia , Benzopiranos/farmacologia , Cicloleucina/análogos & derivados , Cicloleucina/farmacologia , Relação Dose-Resposta a Droga , Ingestão de Alimentos/fisiologia , Glicina/análogos & derivados , Glicina/farmacologia , Hipotálamo/fisiologia , Masculino , Fenilacetatos/farmacologia , Piridinas/farmacologia , Ratos , Ratos Sprague-Dawley , Receptor de Glutamato Metabotrópico 5/agonistas , Receptor de Glutamato Metabotrópico 5/antagonistas & inibidores , Receptores de Glutamato Metabotrópico/agonistas , Receptores de Glutamato Metabotrópico/antagonistas & inibidores , Resorcinóis/farmacologia , Tiazóis/farmacologia , Fatores de Tempo
10.
Ross Fiziol Zh Im I M Sechenova ; 100(10): 1169-79, 2014 Oct.
Artigo em Russo | MEDLINE | ID: mdl-25697024

RESUMO

Whole-cell patch-clamp recordings from isolated neurons from rat prefrontal cortex have been made to study GABAb and mGluR receptor modulation of currents induced by applications of GABA and kainate. The GABAb-receptor antagonist CGP-55845 (5 microM) enhanced the peak by 26 +/- 13% (n = 6) but had no effect on the steady-state of GABA-activated current. Bath application of GABAb-receptor agonist baclofen (50 microM) enhanced the GABAa currents by 9 +/- 2% (n = 8). Kainate-activated currents were not affected by baclofen. Both GABA-activated currents and kainate-activated currents were not affected by trans-ACPD (MGluR agonist). These results suggest that in cortex postsynaptic response of GABAa-receptors can be modulated by GABAb-receptors.


Assuntos
Agonistas de Aminoácidos Excitatórios/farmacologia , Ácido Caínico/farmacologia , Células Piramidais/metabolismo , Receptores de GABA-B/imunologia , Transmissão Sináptica/efeitos dos fármacos , Ácido gama-Aminobutírico/farmacologia , Animais , Baclofeno/farmacologia , Cicloleucina/análogos & derivados , Cicloleucina/farmacologia , Feminino , Antagonistas GABAérgicos/farmacologia , Agonistas dos Receptores de GABA-B/farmacologia , Masculino , Fármacos Neuroprotetores/farmacologia , Ácidos Fosfínicos/farmacologia , Propanolaminas/farmacologia , Células Piramidais/citologia , Ratos , Ratos Wistar , Receptores de Glutamato Metabotrópico , Transmissão Sináptica/fisiologia
11.
J Neurosci ; 33(19): 8411-22, 2013 May 08.
Artigo em Inglês | MEDLINE | ID: mdl-23658179

RESUMO

Calcium-dependent release of vasoactive gliotransmitters is widely assumed to trigger vasodilation associated with rapid increases in neuronal activity. Inconsistent with this hypothesis, intact stimulus-induced vasodilation was observed in inositol 1,4,5-triphosphate (IP3) type-2 receptor (R2) knock-out (KO) mice, in which the primary mechanism of astrocytic calcium increase-the release of calcium from intracellular stores following activation of an IP3-dependent pathway-is lacking. Further, our results in wild-type (WT) mice indicate that in vivo onset of astrocytic calcium increase in response to sensory stimulus could be considerably delayed relative to the simultaneously measured onset of arteriolar dilation. Delayed calcium increases in WT mice were observed in both astrocytic cell bodies and perivascular endfeet. Thus, astrocytes may not play a role in the initiation of blood flow response, at least not via calcium-dependent mechanisms. Moreover, an increase in astrocytic intracellular calcium was not required for normal vasodilation in the IP3R2-KO animals.


Assuntos
Astrócitos/metabolismo , Cálcio/metabolismo , Receptores de Inositol 1,4,5-Trifosfato/deficiência , Vasodilatação/fisiologia , Potenciais de Ação/efeitos dos fármacos , Potenciais de Ação/genética , Trifosfato de Adenosina/farmacologia , Animais , Astrócitos/citologia , Astrócitos/efeitos dos fármacos , Cicloleucina/análogos & derivados , Cicloleucina/farmacologia , Dextranos/metabolismo , Ácido Egtázico/análogos & derivados , Ácido Egtázico/metabolismo , Estimulação Elétrica , Feminino , Fluoresceína-5-Isotiocianato/análogos & derivados , Fluoresceína-5-Isotiocianato/metabolismo , Hipercalcemia/fisiopatologia , Masculino , Camundongos , Camundongos Endogâmicos ICR , Camundongos Knockout , Neurônios/efeitos dos fármacos , Neurônios/fisiologia , Fármacos Neuroprotetores/farmacologia , Transdução de Sinais , Fatores de Tempo , Vasodilatação/efeitos dos fármacos
12.
PLoS One ; 7(8): e42194, 2012.
Artigo em Inglês | MEDLINE | ID: mdl-22876307

RESUMO

Functional hyperemia of the cerebral vascular system matches regional blood flow to the metabolic demands of the brain. One current model of neurovascular control holds that glutamate released by neurons activates group I metabotropic glutamate receptors (mGluRs) on astrocytes, resulting in the production of diffusible messengers that act to regulate smooth muscle cells surrounding cerebral arterioles. The acute mouse brain slice is an experimental system in which changes in arteriole diameter can precisely measured with light microscopy. Stimulation of the brain slice triggers specific cellular responses that can be correlated to changes in arteriole diameter. Here we used inositol trisphosphate receptor type 2 (IP(3)R2) and cytosolic phospholipase A(2) alpha (cPLA(2)α) deficient mice to determine if astrocyte mGluR activation coupled to IP(3)R2-mediated Ca(2+) release and subsequent cPLA(2)α activation is required for arteriole regulation. We measured changes in astrocyte cytosolic free Ca(2+) and arteriole diameters in response to mGluR agonist or electrical field stimulation in acute neocortical mouse brain slices maintained in 95% or 20% O(2). Astrocyte Ca(2+) and arteriole responses to mGluR activation were absent in IP(3)R2(-/-) slices. Astrocyte Ca(2+) responses to mGluR activation were unchanged by deletion of cPLA(2)α but arteriole responses to either mGluR agonist or electrical stimulation were ablated. The valence of changes in arteriole diameter (dilation/constriction) was dependent upon both stimulus and O(2) concentration. Neuron-derived NO and activation of the group I mGluRs are required for responses to electrical stimulation. These findings indicate that an mGluR/IP(3)R2/cPLA(2)α signaling cascade in astrocytes is required to transduce neuronal glutamate release into arteriole responses.


Assuntos
Arteríolas/fisiologia , Astrócitos/metabolismo , Encéfalo/irrigação sanguínea , Encéfalo/metabolismo , Fosfolipases A2 do Grupo IV/metabolismo , Receptores de Inositol 1,4,5-Trifosfato/metabolismo , Animais , Arteríolas/efeitos dos fármacos , Sinalização do Cálcio , Cicloleucina/análogos & derivados , Cicloleucina/farmacologia , Ativação Enzimática , Feminino , Regulação da Expressão Gênica/efeitos dos fármacos , Fosfolipases A2 do Grupo IV/genética , Receptores de Inositol 1,4,5-Trifosfato/genética , Masculino , Camundongos , Camundongos Knockout , Óxido Nítrico Sintase Tipo I/antagonistas & inibidores , Receptores de Glutamato Metabotrópico/agonistas , Transdução de Sinais
13.
J Nutr Biochem ; 23(11): 1531-6, 2012 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-22402366

RESUMO

We investigated the molecular response to folate metabolism inhibition by exposing human lymphoblast cell lines to the methionine adenosyltransferase inhibitor cycloleucine. We carried out microarray analysis on replicate control and exposed cells by examining 47,000 transcripts on the Affymetrix HG U133 plus 2.0 arrays. We identified 13 genes that we considered reliable responders to cycloleucine treatment: chemokine receptor 3 (CXCR3), prostaglandin-endoperoxide synthase 2, growth arrest-specific 7, reduced folate carrier, klotho beta, early growth response 1, diaphanous homolog 3, prostaglandin D2 synthase (PGDS), butyrophilin-like 9, low-density lipoprotein receptor-related protein 11, chromosome 21 orf15, G-protein-coupled receptor 98 (GPR98) and cystathionine-beta-synthase (CBS). We further demonstrated that four of these genes, CXCR3, PGDS, GPR98 and CBS, consistently responded to cycloleucine treatment in additional experiments over a range of concentrations. We carried out gene-specific DNA methylation analysis on five genes, including CBS, and found no evidence that DNA methylation changes were mediating the gene expression changes observed. Pathway analysis of the microarray data identified four pathways of relevance for response to cycloleucine; the immune response NF-AT signaling pathway was the most statistically significant. Comparison with other gene expression studies focusing on folate deficiency revealed that gene products related to immune cells or the immune response is a common theme. This indicates that apart from their role in the immune response, it is likely that these gene products may also have a role to play in the cellular response to folate status.


Assuntos
Ácido Fólico/genética , Ácido Fólico/metabolismo , Regulação da Expressão Gênica , Adenosina Desaminase/genética , Adenosina Desaminase/metabolismo , Linhagem Celular/efeitos dos fármacos , Subunidade alfa 2 de Fator de Ligação ao Core/genética , Subunidade alfa 2 de Fator de Ligação ao Core/metabolismo , Cicloleucina/farmacologia , Cistationina beta-Sintase/genética , Cistationina beta-Sintase/metabolismo , Metilação de DNA , Relação Dose-Resposta a Droga , Fatores de Transcrição Forkhead/genética , Fatores de Transcrição Forkhead/metabolismo , Regulação da Expressão Gênica/efeitos dos fármacos , Humanos , Oxirredutases Intramoleculares/genética , Oxirredutases Intramoleculares/metabolismo , Lipocalinas/genética , Lipocalinas/metabolismo , Análise em Microsséries , Proteínas de Ligação a RNA , Receptores CXCR3/genética , Receptores CXCR3/metabolismo , Receptores Acoplados a Proteínas-G/genética , Receptores Acoplados a Proteínas-G/metabolismo , Reprodutibilidade dos Testes , Transdução de Sinais/efeitos dos fármacos , Transdução de Sinais/genética
14.
BMB Rep ; 45(2): 126-31, 2012 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-22360892

RESUMO

We have previously identified a DNA silent region located downstream of the 3'-end of the ß(major) globin gene (designated B1-559) that contains a B1 retrotransposon, consensus binding sites for erythroid specific transcription factors and shares the capacity to act as promoter in hematopoietic cells interacting with ß-globin gene LCR sequences in vitro. In this study, we have cloned four new non-polyA RNA transcripts being detected upon blockade of murine erythroleukemia (MEL) cell differentiation to erythroid maturation by methylation inhibitors and demonstrated that two of them share high structural homology with sequences of B1 element found within the B1-559 region. Although it is not clear yet whether and how these RNAs interfere with induction of erythroid maturation, these data provide evidence for the first time showing that methylation inhibitors can activate silent repetitive DNA sequences in MEL cells and may have implications in cancer chemotherapy using demethylating drugs as antineoplastic agents.


Assuntos
Retroelementos/genética , Globinas beta/genética , Adenosina/análogos & derivados , Adenosina/farmacologia , Animais , Diferenciação Celular/efeitos dos fármacos , Linhagem Celular Tumoral , Clonagem Molecular , Cicloleucina/farmacologia , Metilação de DNA/efeitos dos fármacos , Dimetil Sulfóxido/metabolismo , Leucemia Eritroblástica Aguda/genética , Leucemia Eritroblástica Aguda/metabolismo , Camundongos , Dados de Sequência Molecular , Poli A/metabolismo , RNA/metabolismo
15.
Mol Vis ; 17: 920-31, 2011 Apr 12.
Artigo em Inglês | MEDLINE | ID: mdl-21541265

RESUMO

PURPOSE: Vision is encoded at photoreceptor synapses by the number of released vesicles and size of the post-synaptic response. We hypothesized that elevating cytosolic glutamate could enhance quantal size by increasing glutamate in vesicles. METHODS: We introduced glutamate (10-40 mM) into cone terminals through a patch pipette and recorded excitatory post-synaptic currents (EPSCs) from horizontal or OFF bipolar cells in the Ambystoma tigrinum retinal slice preparation. RESULTS: Elevating cytosolic glutamate in cone terminals enhanced EPSCs as well as quantal miniature EPSCs (mEPSCs). Enhancement was prevented by inhibiting vesicular glutamate transport with 1S,3R-1-aminocyclopentane-1,3-dicarboxylate in the patch pipette. A low affinity glutamate receptor antagonist, γD-glutamylglycine (1 mM), less effectively inhibited EPSCs evoked from cones loaded with glutamate than control cones indicating that release from cones with supplemental glutamate produced higher glutamate levels in the synaptic cleft. Raising presynaptic glutamate did not alter exocytotic capacitance responses and exocytosis was observed after inhibiting glutamate loading with the vesicular ATPase inhibitor, concanamycin A, suggesting that release capability is not restricted by low vesicular glutamate levels. Variance-mean analysis of currents evoked by flash photolysis of caged glutamate indicated that horizontal cell AMPA receptors have a single channel conductance of 10.1 pS suggesting that ~8.7 GluRs contribute to each mEPSC. CONCLUSIONS: Quantal amplitude at the cone ribbon synapse is capable of adjustment by changes in cytosolic glutamate levels. The small number of channels contributing to each mEPSC suggests that stochastic variability in channel opening could be an important source of quantal variability.


Assuntos
Ácido Glutâmico/farmacologia , Células Fotorreceptoras Retinianas Cones/metabolismo , Sinapses/efeitos dos fármacos , Vesículas Sinápticas/metabolismo , Ambystoma/fisiologia , Animais , Cicloleucina/análogos & derivados , Cicloleucina/farmacologia , Citosol/efeitos dos fármacos , Citosol/metabolismo , Inibidores Enzimáticos/farmacologia , Antagonistas de Aminoácidos Excitatórios/farmacologia , Potenciais Pós-Sinápticos Excitadores/efeitos dos fármacos , Potenciais Pós-Sinápticos Excitadores/fisiologia , Exocitose/efeitos dos fármacos , Macrolídeos/farmacologia , Receptores de Glutamato/metabolismo , Células Fotorreceptoras Retinianas Cones/citologia , Processos Estocásticos , Sinapses/fisiologia , Transmissão Sináptica/efeitos dos fármacos , Vesículas Sinápticas/efeitos dos fármacos , Visão Ocular/fisiologia
16.
J Biomol Screen ; 15(10): 1238-47, 2010 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-20811068

RESUMO

Recently, new technologies based on biosensors and called label free have been developed. These technologies eliminate the need for using markers and dyes. The authors applied one of these technologies, based on measurement of cell impedance variation, to study the pharmacological profiles of ligands for the cannabinoid receptor 2 (CB2), a Gi-coupled receptor, and for the metabopotropic glutamate receptor 1 (mGluR1), a Gq-coupled receptor. Reference agonists and antagonists/inverse agonists for the 2 receptors were applied to recombinant cell lines and impedance monitored over time. Agonists (JWH133 and CP55940 for CB2; quisqualate, glutamate, 1S-3R-ACPD, and S-3,5-DHPG for mGluR1) triggered a variation of impedance consistent in both potency and efficacy with data obtained using classical assays measuring cAMP or Ca(2+) levels. This effect was not present in the parental nontransfected cell line, confirming specific receptor-mediated response. Application of antagonists (AM630 for CB2; YM298198, SCH1014222, J&J16259685, and CPCCOEt for mGluR1) reduced agonist-induced impedance changes. The only exception was the mGluR1 antagonist BAY367620 that, while active in the Ca(2+) assay, was inactive in the impedance assay. Overall, these results confirm the possibility of using cell impedance-based technology to study the pharmacological profile of ligands acting at G-protein-coupled receptors coupled to different downstream signaling pathways.


Assuntos
Receptor CB2 de Canabinoide/agonistas , Receptor CB2 de Canabinoide/antagonistas & inibidores , Receptores de Glutamato Metabotrópico/agonistas , Receptores de Glutamato Metabotrópico/antagonistas & inibidores , Analgésicos/farmacologia , Animais , Benzimidazóis/farmacologia , Bioensaio , Células CHO , Cálcio/metabolismo , Canabinoides/farmacologia , Cromonas , Cricetinae , Cricetulus , AMP Cíclico/metabolismo , Cicloexanóis/farmacologia , Cicloleucina/análogos & derivados , Cicloleucina/farmacologia , Impedância Elétrica , Agonistas de Aminoácidos Excitatórios/farmacologia , Antagonistas de Aminoácidos Excitatórios/farmacologia , Ácido Glutâmico/metabolismo , Ácido Glutâmico/farmacologia , Glicina/análogos & derivados , Glicina/farmacologia , Indóis/farmacologia , Naftalenos/farmacologia , Fármacos Neuroprotetores/farmacologia , Quinolinas/farmacologia , Ácido Quisquálico/farmacologia , Receptor CB2 de Canabinoide/metabolismo , Receptores de Glutamato Metabotrópico/metabolismo , Resorcinóis/farmacologia , Transdução de Sinais/efeitos dos fármacos , Transdução de Sinais/fisiologia , Tiazóis/farmacologia
17.
Am J Physiol Regul Integr Comp Physiol ; 298(3): R584-98, 2010 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-20007519

RESUMO

Human primary and clonal synovial cells were incubated with glutamate receptor agonists to assess their modulating influence on glutamate receptors N-methyl-d-aspartate (NMDA) NR1 and NR2 and inflammatory cytokines to determine potential for paracrine or autocrine (neurocrine) upregulation of glutamate receptors, as has been shown for bone and chondrocytes. Clonal SW982 synoviocytes constitutively express vimentin, smooth muscle actin (SMA), and NMDA NR1 and NR2. Coincubation (6 h) with glutamate agonists NMDA (5 microM), and the NMDA NR1 glycine site activator (+/-)1-aminocyclopentane-cis-1,3-dicarboxylic acid (5 muM), significantly increases cellular mRNA and protein levels of glutamate receptors, as well as increasing vimentin, SMA, tumor necrosis factor-alpha, and RANTES (regulated on activation, normal T-cell expressed and secreted), assessed qualitatively and quantitatively with nucleotide amplification, image analysis of immunocytochemical staining, fluorescein-activated cell sorting, Western blotting, and immunoassays. Human primary synovial cells harvested from patients with arthritic conditions also constitutively expressed NMDA NR1 with increases after agonist treatment. Glutamate receptor agonist-induced increases were blocked by the noncompetitive glutamate antagonist MK-801 (8 microg/ml) and NR1 blocking antibody. Coincubation with glutamate agonists and phorbol 12-myristate 13-acetate, a protein kinase C activator, significantly enhanced mean levels of TNF-alpha and RANTES in SW982 cell supernatants compared with incubation with either agent alone. Increases were diminished with protein kinase inhibitor and NR1 blocking antibody. The functional activation of glutamate receptors on human synoviocytes establishes a neurogenic cell signaling link between neurotransmitter glutamate released from nerve terminals and target cells in the joint capsule. The influence of glutamate on subsequent release of cellular proinflammatory mediators in non-neural tissue for activation of downstream immune events supports a peripheral neuroimmune link in arthritis.


Assuntos
Quimiocina CCL5/metabolismo , Inflamação Neurogênica/fisiopatologia , Receptores de N-Metil-D-Aspartato/genética , Sinovite/fisiopatologia , Fator de Necrose Tumoral alfa/metabolismo , Vimentina/metabolismo , Animais , Artrite/metabolismo , Artrite/fisiopatologia , Antígeno CD11b/metabolismo , Linhagem Celular Tumoral , Cicloleucina/análogos & derivados , Cicloleucina/farmacologia , Maleato de Dizocilpina/farmacologia , Agonistas de Aminoácidos Excitatórios/farmacologia , Antagonistas de Aminoácidos Excitatórios/farmacologia , Humanos , N-Metilaspartato/farmacologia , Inflamação Neurogênica/metabolismo , Neuroimunomodulação/fisiologia , Proteína Quinase C/metabolismo , RNA Mensageiro/metabolismo , Ratos , Receptores de Complemento 3d/metabolismo , Receptores de Glutamato/metabolismo , Receptores de N-Metil-D-Aspartato/agonistas , Receptores de N-Metil-D-Aspartato/metabolismo , Sarcoma Sinovial , Membrana Sinovial/citologia , Membrana Sinovial/fisiologia , Sinovite/metabolismo , Regulação para Cima/efeitos dos fármacos , Regulação para Cima/fisiologia , Vimentina/genética
18.
Comp Biochem Physiol C Toxicol Pharmacol ; 150(4): 546-57, 2009 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-19695344

RESUMO

Drosophila melanogaster larval neuromuscular junctions (NMJs) serve as a model for synaptic physiology. The molecular sequences of the postsynaptic glutamate receptors have been described; however, the pharmacological profile has not been fully elucidated. The postsynaptic molecular sequence suggests a novel glutamate receptor subtype. Kainate does not depolarize the muscle, but dampens evoked EPSP amplitudes. Quantal responses show a decreased amplitude and area under the voltage curve indicative of reduced postsynaptic receptor sensitivity to glutamate transmission. ATPA, a kainate receptor agonist, did not mimic kainate's action. The metabotropic glutamate receptor agonist t-ACPD had no effect. Domoic acid, a kainate/AMPA receptor agonist, blocks the postsynaptic receptors without depolarizing the muscle. However, SYM 2081, a kainate receptor agonist, did depolarize the muscle and reduce the EPSP amplitude at 1 mM but not at 0.1 mM. This supports the notion that these are generally a quisqualate subtype receptors with some oddities in the pharmacological profile. The results suggest a direct postsynaptic action of kainate due to partial antagonist action on the quisqualate receptors. There does not appear to be presynaptic auto-regulation via a kainate receptor subtype or a metabotropic auto-receptor. This study aids in furthering the pharmokinetic profiling and specificity of the receptor subtypes.


Assuntos
Drosophila/fisiologia , Junção Neuromuscular/efeitos dos fármacos , Receptores de Glutamato/efeitos dos fármacos , Receptores de Glutamato/fisiologia , Receptores de Glutamato Metabotrópico/fisiologia , Vias Aferentes/efeitos dos fármacos , Animais , Benzodiazepinas/farmacologia , Cicloleucina/análogos & derivados , Cicloleucina/farmacologia , Relação Dose-Resposta a Droga , Eletrofisiologia , Potenciais Pós-Sinápticos Excitadores/efeitos dos fármacos , Glutamatos/farmacologia , Glutamatos/fisiologia , Ácido Caínico/análogos & derivados , Ácido Caínico/farmacologia , Larva/fisiologia , Junção Neuromuscular/fisiologia , Receptores de AMPA/antagonistas & inibidores , Receptores de Ácido Caínico/agonistas , Receptores de Glutamato Metabotrópico/agonistas , Receptores de Glutamato Metabotrópico/efeitos dos fármacos , Transmissão Sináptica/efeitos dos fármacos , Transmissão Sináptica/fisiologia , Ácido alfa-Amino-3-hidroxi-5-metil-4-isoxazol Propiônico/agonistas
19.
Synapse ; 63(12): 1060-8, 2009 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-19637276

RESUMO

Mossy fiber long-term depression (LTD) has been shown to be triggered by either pharmacological or synaptic activation of Group II metabotropic glutamate receptors (mGluRs) whereas other studies indicate that synaptic activation of mGluRs is very limited. Therefore, we reexamined the role of Group II mGluRs for the induction of mossy fiber LTD. The complete depression of field potentials (fEPSPs) by 1 microM (2S,2'R,3'R)-2-(2',3'-Dicarboxycyclopropyl)glycine (DCG-IV) only partially reversed upon removal of the drug but fEPSPs were completely restored by the Group II antagonist 2S-2-amino-2-(1S,2S-2-carboxycyclopropyl-1-yl)-3-(xanth-9-yl)propanoic acid (LY341495) (3 microM). In contrast, fEPSPs returned back to baseline within 30 min after a brief application of 0.2 microM DCG-IV suggesting that the incomplete reversal of higher concentrations may be due to a residual receptor occupancy rather than to an induction of LTD. LY341495 itself did not increase fEPSPs and also blocked the inhibition of (2S,1'S,2'S)-2-(2-carboxycyclopropyl)glycine (L-CCG-I) (20 microM) and (1S,3R)-1-aminocyclopentane-1,3-dicarboxylic acid (ACPD) (10 microM) and its effect was mimicked by CPPG (50 microM). Furthermore, stimulation at 1 Hz for 15 min induced an LTD of 81% +/- 3% and 80% +/- 4% in the absence and presence of LY341495, respectively (n = 7, 5). Finally, we found that synaptic activation of Group II mGluRs during 15 min of 1-Hz stimulation only produces an inhibition of release by 8% +/- 1% (30 degrees C, n = 3). Our data suggests that pharmacological activation of Group II mGluRs is fully reversible per se and does not produce a long lasting depression and that activation of Group II mGluRs is neither necessary nor sufficient for the induction of mossy fiber LTD.


Assuntos
Hipocampo/fisiologia , Depressão Sináptica de Longo Prazo/fisiologia , Neurônios/fisiologia , Receptores de Glutamato Metabotrópico/metabolismo , Aminoácidos/farmacologia , Aminoácidos Dicarboxílicos/farmacologia , Animais , Cicloleucina/análogos & derivados , Cicloleucina/farmacologia , Ciclopropanos/farmacologia , Estimulação Elétrica , Agonistas de Aminoácidos Excitatórios/farmacologia , Antagonistas de Aminoácidos Excitatórios/farmacologia , Potenciais Pós-Sinápticos Excitadores/efeitos dos fármacos , Potenciais Pós-Sinápticos Excitadores/fisiologia , Glicina/análogos & derivados , Glicina/farmacologia , Hipocampo/efeitos dos fármacos , Técnicas In Vitro , Depressão Sináptica de Longo Prazo/efeitos dos fármacos , Camundongos , Camundongos Endogâmicos C57BL , Inibição Neural/efeitos dos fármacos , Inibição Neural/fisiologia , Neurônios/efeitos dos fármacos , Ratos , Ratos Wistar , Receptores de Glutamato Metabotrópico/agonistas , Receptores de Glutamato Metabotrópico/antagonistas & inibidores , Transmissão Sináptica/efeitos dos fármacos , Transmissão Sináptica/fisiologia , Xantenos/farmacologia
20.
J Neurophysiol ; 101(4): 1761-73, 2009 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-19176605

RESUMO

The ventral lateral geniculate nucleus (vLGN) has been implicated in numerous functions including circadian rhythms, brightness discrimination, pupillary light reflex, and other visuomotor functions. The contribution of inhibitory mechanisms in the regulation of vLGN neuron excitability remains unexplored. We examined the actions of metabotropic glutamate receptor (mGluR) activation on the intrinsic excitability and inhibitory synaptic transmission in different lamina of vLGN. Activation of mGluRs exerts distinct pre- and postsynaptic actions in vLGN neurons. In the lateral magnocellular subdivision of vLGN (vLGNl), the general mGluR agonist (1S,3R)-1-aminocyclopentane-1,3-dicarboxylic acid (ACPD) enhanced the frequency of GABA(A) receptor-mediated spontaneous inhibitory postsynaptic currents (sIPSC) that persisted in the presence of sodium channel blocker tetrodotoxin (TTX) in a subpopulation of neurons (TTX insensitive). This increase is attributed to the increased output of dendritic GABA release from vLGN interneurons. In contrast, in the medial subdivision of vLGN (vLGNm), the mGluR agonist-mediated increase in sIPSC frequency was completely blocked by TTX. The selective Group I mGluR agonist (RS)-3,5-dihydroxyphenylglycine (DHPG) increased sIPSC frequency, whereas the selective Group II mGluR agonist (2R, 4R)-4-aminopyrrolidine-2,4-dicarboxylate (APDC) significantly decreased sIPSC frequency in vLGNl neurons. Optic tract stimulation also produced an mGluR-dependent increase in sIPSC frequency in vLGNl neurons. In contrast, we were unable to synaptically evoke alterations in sIPSC activity in vLGNm neurons. In addition to these presynaptic actions, DHPG depolarized both vLGNl and vLGNm neurons. In vLGN interneurons, mGluR activation produced opposing actions: APDC hyperpolarized the membrane potential, whereas DHPG produced a membrane depolarization. The present findings demonstrate diverse actions of mGluRs on vLGN neurons localized within different vLGN lamina. Considering these different lamina are coupled with distinct functional roles, thus these diverse actions may be involved in distinctive forms of visual and visuomotor information processing.


Assuntos
Corpos Geniculados/citologia , Inibição Neural/fisiologia , Neurônios/fisiologia , Receptores de Glutamato Metabotrópico/fisiologia , Animais , Animais Recém-Nascidos , Mapeamento Encefálico , Cicloleucina/farmacologia , Dioxolanos/farmacologia , Interações de Medicamentos , Estimulação Elétrica/métodos , Antagonistas de Aminoácidos Excitatórios/farmacologia , Antagonistas GABAérgicos/farmacologia , Técnicas In Vitro , Potenciais Pós-Sinápticos Inibidores/efeitos dos fármacos , Potenciais Pós-Sinápticos Inibidores/fisiologia , Metoxi-Hidroxifenilglicol/análogos & derivados , Metoxi-Hidroxifenilglicol/farmacologia , Inibição Neural/efeitos dos fármacos , Neurônios/classificação , Neurônios/efeitos dos fármacos , Técnicas de Patch-Clamp/métodos , Purinas/farmacologia , Piridazinas/farmacologia , Ratos , Ratos Sprague-Dawley , Receptores de Glutamato Metabotrópico/antagonistas & inibidores , Bloqueadores dos Canais de Sódio/farmacologia , Tetrodotoxina/farmacologia
SELEÇÃO DE REFERÊNCIAS
DETALHE DA PESQUISA