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1.
Cell Death Dis ; 2: e144, 2011 Apr 14.
Artigo em Inglês | MEDLINE | ID: mdl-21490676

RESUMO

Autophagy is the major intracellular degradation pathway that regulates long-lived proteins and organelles turnover. This process occurs at basal levels in all cells but it is rapidly upregulated in response to starvation and cellular stress. Although being recently implicated in neurodegeneration, it remains still unclear whether autophagy has a detrimental or protective role. In this study, we investigated the dynamics of the autophagic process in retinal tissue that has undergone transient ischemia, an experimental model that recapitulates features of ocular pathologies, including glaucoma, anterior ischemic optic neuropathy and retinal vessels occlusion. Retinal ischemia, induced in adult rats by increasing the intraocular pressure, was characterized by a reduction in the phosphatidylethanolamine-modified form of LC3 (LC3II) and by a significant decrease in Beclin-1. The latter event was associated with a proteolytic cleavage of Beclin-1, leading to the accumulation of a 50-kDa fragment. This event was prevented by intravitreal treatment with the non-competitive N-methyl-D-aspartate antagonist MK801 and calpain inhibitors or by calpain knockdown. Blockade of autophagy by pharmacological inhibition or Beclin-1 silencing in RGC-5 increased cell death, suggesting a pro-survival role of the autophagic process in this neuronal cell type. Altogether, our results provide original evidence for calpain-mediated cleavage of Beclin-1 and deregulation of basal autophagy in the rat retina that has undergone ocular ischemia/reperfusion injury.


Assuntos
Proteínas Reguladoras de Apoptose/metabolismo , Autofagia , Calpaína/metabolismo , Rim/irrigação sanguínea , Traumatismo por Reperfusão/metabolismo , Animais , Proteínas Reguladoras de Apoptose/genética , Proteína Beclina-1 , Calpaína/genética , Linhagem Celular , Modelos Animais de Doenças , Humanos , Isquemia/genética , Isquemia/metabolismo , Rim/metabolismo , Masculino , Processamento de Proteína Pós-Traducional , Ratos , Ratos Wistar , Receptores de N-Metil-D-Aspartato/genética , Receptores de N-Metil-D-Aspartato/metabolismo , Traumatismo por Reperfusão/genética , Traumatismo por Reperfusão/fisiopatologia
2.
J Neurochem ; 107(5): 1347-57, 2008 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-18803692

RESUMO

Loss of retinal ganglion cells occurs in a variety of pathological conditions, including central retinal artery occlusion, diabetes and glaucoma. Using an experimental model of retinal ischemia induced by transiently raise the intraocular pressure (IOP), In this study, we report the original observation that ischemic retinal ganglion cells death is associated with the transient deactivation of the pro-survival kinase Akt and activation of GSK-3beta followed, during reperfusion, by a longer lasting, PI3K-dependent, activation of Akt and phosphorylation of GSK-3beta. Under these experimental conditions, retinal ischemia induced the expression of Bad, a pro-apoptotic protein, member of the Bcl-2 family. The detrimental effects yielded by the ischemic stimulus were minimized by intravitreal administration of the NMDA receptor antagonist, MK801, that reduced the expression of Bad and significantly increased Akt phosphorylation. In conclusion, our present results contribute to unravel the mechanisms underlying retinal damage by high IOP-induced transient ischemia in rat. In addition, these data implicate the pro-survival PI3K/Akt pathway and the observed reduced expression of Bad in the neuroprotection afforded by MK801.


Assuntos
Receptores de N-Metil-D-Aspartato/fisiologia , Traumatismo por Reperfusão/fisiopatologia , Doenças Retinianas/fisiopatologia , Transdução de Sinais/fisiologia , Análise de Variância , Androstadienos/farmacologia , Animais , Morte Celular/fisiologia , Cromonas/farmacologia , Maleato de Dizocilpina/farmacologia , Inibidores Enzimáticos/farmacologia , Quinase 3 da Glicogênio Sintase/metabolismo , Glicogênio Sintase Quinase 3 beta , Pressão Intraocular/fisiologia , Isquemia/complicações , Isquemia/fisiopatologia , Masculino , Morfolinas/farmacologia , Proteína Oncogênica v-akt/metabolismo , PTEN Fosfo-Hidrolase/metabolismo , Proteínas Proto-Oncogênicas c-bcl-2/metabolismo , Ratos , Ratos Wistar , Receptores de N-Metil-D-Aspartato/antagonistas & inibidores , Traumatismo por Reperfusão/etiologia , Doenças Retinianas/complicações , Doenças Retinianas/patologia , Serina/metabolismo , Transdução de Sinais/efeitos dos fármacos , Fatores de Tempo , Wortmanina , Proteína de Morte Celular Associada a bcl/metabolismo
3.
Pharmacol Biochem Behav ; 84(3): 453-67, 2006 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-16859739

RESUMO

The aim of the present work was the assessment of the effects produced on the electroencephalographic (EEG) activity and the cognitive and memory performances of nucleus basalis magnocellularis (NBM)-lesioned or aged rats by the combined treatment with [2-(2,2-dimethylpropionyloxy)ethyl]trimethylammonium 2,2-dimethylpropionate (choline pivaloyl ester) (CPE) and the Cholinesterase inhibitors (ChEIs) Tacrine (THA) and Galantamine (GAL). Intraperitoneal administration of CPE combined with THA or GAL to both NBM-lesioned or aged rats, produced EEG desynchronisation, and a significant decrease in the energy of the total EEG spectrum and the lower frequency bands (delta 0.25-3 and theta 4-7 Hz) lasting many minutes. Furthermore, drug associations reversed in aged rats the scopolamine (0.2 mg/kg, i.p.)-induced increase in EEG power, slow waves and high-voltage spindle (HVS). Furthermore, the combined administration of CPE and Cholinesterase inhibitors in both NBM-lesioned or aged animals, improved performances in all behavioural tasks, enhancing object discrimination, increasing locomotory activity and alternation choice in T-maze, ameliorating retention in passive avoidance and decreasing escape latency in Morris water maze. In all test, AChEIs and CPE combinations proved to be more effective than CPE, THA or GAL given alone. In conclusion, the present work shows the ability of choline pivaloyl ester in strengthening the positive cerebral activity of THA and GAL.


Assuntos
Colina/análogos & derivados , Colina/farmacologia , Eletroencefalografia/métodos , Galantamina/farmacologia , Tacrina/farmacologia , Animais , Comportamento Animal , Inibidores da Colinesterase/farmacologia , Relação Dose-Resposta a Droga , Sinergismo Farmacológico , Inibidores Enzimáticos/farmacologia , Masculino , Ratos , Ratos Wistar , Escopolamina/farmacologia
4.
Toxicol Lett ; 139(2-3): 199-206, 2003 Apr 04.
Artigo em Inglês | MEDLINE | ID: mdl-12628755

RESUMO

Neuronal loss has often been described at post-mortem in the brain neocortex of patients suffering from AIDS. Neuroinvasive strains of HIV infect macrophages, microglial cells and multinucleated giant cells but not neurones. Processing of the virus by cells of the myelomonocytic lineage yields viral products that, in conjunction with potentially neurotoxic molecules generated by the host, might initiate a complex network of events which leads neurones to death. In particular, the HIV-1 coat glycoprotein gp120 has been proposed as a likely aetiologic agent of the described neuronal loss because it causes death of neurones in culture. More recently, it has been shown that brain neocortical cell death is caused in rat by intracerebroventricular injection of a recombinant gp120 coat protein and this occurs via apoptosis. The latter observation broadens our knowledge in the pathophysiology of the reported neuronal cell loss and opens a new lane of experimental research for the development of novel therapeutic strategies to limit damage to the brain of patients suffering from HIV associated dementia.


Assuntos
Complexo AIDS Demência/metabolismo , Complexo AIDS Demência/patologia , Apoptose , Neurônios/metabolismo , Neurônios/patologia , Complexo AIDS Demência/enzimologia , Animais , Ciclo-Oxigenase 2 , Proteína gp120 do Envelope de HIV/metabolismo , Interleucina-1/metabolismo , Isoenzimas/metabolismo , Neocórtex/enzimologia , Neocórtex/metabolismo , Neocórtex/patologia , Neurônios/enzimologia , Prostaglandina-Endoperóxido Sintases/metabolismo , Receptores CXCR4/metabolismo
5.
Biochem Biophys Res Commun ; 291(2): 255-60, 2002 Feb 22.
Artigo em Inglês | MEDLINE | ID: mdl-11846398

RESUMO

Administration of tacrine (5 mg/kg ip), an anticholinesterase agent, in rats pretreated (24 h beforehand) with lithium chloride (LiCl; 12 mEq/kg ip) provides a useful experimental model to study limbic seizures and delayed hippocampal damage. Here we report Western blotting evidence demonstrating that in rat LiCl and tacrine enhance the expression of neuronal nitric oxide synthase (nNOS), but not eNOS, enzyme protein in the hippocampus during the preconvulsive period and this triggers seizures and hippocampal damage. In fact, systemic administration of 7-nitro indazole (7-NI; 50 mg/kg given ip 30 min before tacrine), a selective inhibitor of nNOS, prevented the expression of motor and electrocortical (ECoG) seizures and abolished neuronal cell death in the hippocampus. A lower dose (5 mg/kg ip) of 7-NI was ineffective. In conclusion, the present data support a role for abnormal nNOS expression in the mechanism which triggers limbic seizures and delayed excitotoxic damage in the hippocampus of rat.


Assuntos
Hipocampo/patologia , Óxido Nítrico Sintase/biossíntese , Convulsões/enzimologia , Convulsões/etiologia , Animais , Western Blotting , Inibidores da Colinesterase/farmacologia , Inibidores Enzimáticos/farmacologia , Hipocampo/enzimologia , Indazóis/farmacologia , Cloreto de Lítio/antagonistas & inibidores , Masculino , Fármacos Neuroprotetores/farmacologia , Óxido Nítrico Sintase/antagonistas & inibidores , Óxido Nítrico Sintase Tipo I , Ratos , Ratos Wistar , Convulsões/patologia , Tacrina/antagonistas & inibidores
6.
Neurosci Lett ; 314(1-2): 53-6, 2001 Nov 13.
Artigo em Inglês | MEDLINE | ID: mdl-11698145

RESUMO

The effect of IL-1 beta and TNF alpha infused into nucleus tractus solitari (NTS), nucleus parabrachialis medialis (NPBmed) and third cerebral ventricle of normotensive rats on blood pressure (BP) and heart rate (HR) was investigated. Microinfusion of IL-1 beta and TNF alpha into the third cerebral ventricle and NPBmed of normotensive rats produced a dose-dependent hypotensive and bradycardic response. A similar cardiovascular response was produced by infusion of IL1 beta into NTS but not by TNF alpha. When rats were pre-treated with Escherichia coli lipopolisaccharide (LPS), an enhancement of cardiovascular response elicited by IL-1 beta and TNF alpha was found. Thus, IL-1 beta and TNF alpha produce cardiovascular responses when infused into specific areas of the CNS. This effect is potentiated by LPS and this may explain the alteration in cardiovascular regulation which can be observed in diseases in which an excess of circulating endotoxins and cytokines may occur.


Assuntos
Fenômenos Fisiológicos Cardiovasculares/efeitos dos fármacos , Interleucina-1/farmacologia , Ponte/efeitos dos fármacos , Núcleo Solitário/efeitos dos fármacos , Terceiro Ventrículo/efeitos dos fármacos , Fator de Necrose Tumoral alfa/farmacologia , Animais , Infecções Bacterianas/complicações , Infecções Bacterianas/fisiopatologia , Pressão Sanguínea/efeitos dos fármacos , Pressão Sanguínea/fisiologia , Relação Dose-Resposta a Droga , Interações Medicamentosas/fisiologia , Endotoxinas/metabolismo , Frequência Cardíaca/efeitos dos fármacos , Frequência Cardíaca/fisiologia , Lipopolissacarídeos/farmacologia , Masculino , Ponte/fisiologia , Ratos , Ratos Wistar , Núcleo Solitário/fisiologia , Terceiro Ventrículo/fisiologia
7.
J Neurochem ; 79(1): 1-8, 2001 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-11595751

RESUMO

Neuronal loss has often been described at post-mortem in the brain neocortex of patients suffering from AIDS. Neuroinvasive strains of HIV infect macrophages, microglial cells and multinucleated giant cells, but not neurones. Processing of the virus by cells of the myelomonocytic lineage yields viral products that, in conjunction with potentially neurotoxic molecules generated by the host, might initiate a complex network of events which lead neurones to death. In particular, the HIV-1 coat glycoprotein, gp120, has been proposed as a likely aetiologic agent of the described neuronal loss because it causes death of neurones in culture. More recently, it has been shown that brain neocortical cell death is caused in rat by intracerebroventricular injection of a recombinant gp120 coat protein, and that this occurs via apoptosis. The latter observation broadens our knowledge in the pathophysiology of the reported neuronal cell loss and opens a new lane of experimental research for the development of novel therapeutic strategies to limit damage to the brain of patients suffering from HIV-associated dementia.


Assuntos
Apoptose , Proteína gp120 do Envelope de HIV/fisiologia , HIV-1 , Neurônios , Animais , Ciclo-Oxigenase 2 , Indução Enzimática , Expressão Gênica , Proteína gp120 do Envelope de HIV/genética , Humanos , Interleucina-1/genética , Isoenzimas/biossíntese , Proteínas de Membrana , Neocórtex/citologia , Neocórtex/metabolismo , Prostaglandina-Endoperóxido Sintases/biossíntese , Ratos , Transfecção
8.
J Neurosci Res ; 65(4): 354-61, 2001 Aug 15.
Artigo em Inglês | MEDLINE | ID: mdl-11494372

RESUMO

The aim of present study was to investigate the acute effects of ethanol on cytotoxicity induced by HIV-1 coat protein gp120 in CHP100 human neuroblastoma cell line. We demonstrate that ethanol, within a range of clinically relevant concentrations (15-90 mM) prevents cell death elicited by gp120 (10 pM) in a dose dependent manner. This protective action seems to be mediated by a reduction of free intracellular Ca(2+) levels because ethanol, at concentrations ranging from 0.1-0.5%, is able to decrease gp120-stimulated Ca(2+) uptake up to 24%. Furthermore, our data show an involvement of NO/cGMP messenger system pathway, because ethanol is also able to reduce gp120-stimulated NO release (up to 45%) and cyclic GMP accumulation (up to 73%). These findings suggest that the protective effect of ethanol against gp120-induced cytotoxicity in CHP100 cells underlies a Ca(2+)-activated, NO/cGMP-dependent mechanism.


Assuntos
Depressores do Sistema Nervoso Central/farmacologia , Etanol/farmacologia , Proteína gp120 do Envelope de HIV/toxicidade , Neuroblastoma , Neurônios/efeitos dos fármacos , Cálcio/metabolismo , Morte Celular/efeitos dos fármacos , GMP Cíclico/metabolismo , Relação Dose-Resposta a Droga , Agonistas de Aminoácidos Excitatórios/farmacologia , Humanos , N-Metilaspartato/farmacologia , Neurônios/citologia , Neurônios/metabolismo , Óxido Nítrico/metabolismo , Células Tumorais Cultivadas
9.
J Biol Chem ; 276(9): 6529-36, 2001 Mar 02.
Artigo em Inglês | MEDLINE | ID: mdl-11085984

RESUMO

Cell death via apoptosis induced by tumor necrosis factor-alpha (TNF-alpha) plays an important role in many physiological and pathological conditions. The signal transduction pathway activated by this cytokine is known to be regulated by several intracellular messengers. In particular, in many systems nitric oxide (NO) has been shown to protect cells from TNF-alpha-induced apoptosis. However, whether NO can be generated by the cytokine to down-regulate its own apoptotic program has never been studied. We have addressed this question in HeLa Tet-off cell clones stably transfected with the endothelial NO synthase under a tetracycline-responsive promoter. Endothelial NO synthase, induced about 100-fold in these cells by removal of the antibiotic, retained the characteristics of the native enzyme of endothelial cells, both in terms of intracellular localization and functional activity. Expression of the endothelial NO synthase was sufficient to protect from TNF-alpha-induced apoptosis. This protection was mediated by the generation of NO. TNF-alpha itself stimulated endothelial NO synthase activity to generate NO through a pathway involving its lipid messenger, ceramide. Our results identify a novel mechanism of regulation of a signal transduction pathway activated by death receptors and suggest that NO may constitute a built-in mechanism by which TNF-alpha controls its own apoptotic program.


Assuntos
Apoptose/efeitos dos fármacos , Óxido Nítrico Sintase/efeitos dos fármacos , Fator de Necrose Tumoral alfa/farmacologia , Trifosfato de Adenosina/farmacologia , GMP Cíclico/biossíntese , Cicloeximida/farmacologia , Ativação Enzimática/efeitos dos fármacos , Retroalimentação , Células HeLa , Humanos , Morfolinas/farmacologia , NG-Nitroarginina Metil Éster/farmacologia , Óxido Nítrico/biossíntese , Óxido Nítrico Sintase/genética , Óxido Nítrico Sintase Tipo III
11.
Biochem Pharmacol ; 62(12): 1719-24, 2001 Dec 15.
Artigo em Inglês | MEDLINE | ID: mdl-11755126

RESUMO

Mitogen-activated protein kinases (MAPK) play a central role in signal transduction by regulating many nuclear transcription factors involved in inflammatory, immune, and proliferative responses. The aim of this study was to investigate, in human pulmonary endothelial cells, the effects of synthetic glucocorticosteroids on activation of c-jun N-terminal kinases, extracellular signal-regulated kinases, and p38 subgroups of the MAPK family. Human microvascular endothelial cells from lung were stimulated for 2 h with either H(2)O(2) (2 mM), IL-1beta (10 ng/mL), or tumour necrosis factor-alpha (10 ng/mL). Under these conditions, a remarkable increase in the phosphorylation pattern of c-jun N-terminal kinases, extracellular signal-regulated kinases 1/2, and p38 was detected. Pretreatment for 12 h with dexamethasone (100 nM) was able to prevent phosphorylation-dependent MAPK activation in stimulated cells, without substantially affecting the expression levels of these enzymes. Our results suggest that inhibition of MAPK signaling pathways in human pulmonary endothelial cells may significantly contribute, by interfering with activation of several different transcription factors, to the antiinflammatory and immunosuppressive effects of glucocorticosteroids.


Assuntos
Dexametasona/farmacologia , Endotélio Vascular/efeitos dos fármacos , Glucocorticoides/farmacologia , Proteínas Quinases Ativadas por Mitógeno/metabolismo , Células Cultivadas , Endotélio Vascular/enzimologia , Ativação Enzimática/efeitos dos fármacos , Humanos , Proteínas Quinases JNK Ativadas por Mitógeno , Pulmão/citologia , Proteína Quinase 1 Ativada por Mitógeno/metabolismo , Proteína Quinase 3 Ativada por Mitógeno , Fosforilação , Proteínas Quinases p38 Ativadas por Mitógeno
12.
Neuropharmacology ; 39(11): 2147-61, 2000 Aug 23.
Artigo em Inglês | MEDLINE | ID: mdl-10963758

RESUMO

The involvement of GABA(B) receptors in the behavioural and epileptic electrocortical discharges occurring in chemical kindling induced by repeated treatments with a subconvulsant dose of pentylenetetrazole (25 mg/kg i.p.) has been investigated in CD1 mice. Behavioural and electrocorticographic epileptic seizures following kindling induced by pentylenetetrazole (25 mg/kg i.p.) were attenuated or completely antagonized in a dose-dependent manner by the GABA(B) receptor agonist R-baclofen (2 and 6 mg/kg) whilst the GABA(B) receptor antagonist 3-amino-propyl-diethoxy-methyl-phosphinic acid (CGP 35348, 25, 50 or 100 mg/kg) and 3-[1-(S)-(3, 4-dichloro-phenyl-ethyl]amino-2-(S)-hydroxy-propyl-benzyl-phosphinic acid (CGP 55845A, 10 or 20 mg/kg) produced a more rapid development of kindling and an increase in behavioural and electrocorticographic epileptic changes. In addition, all GABA(B) receptor antagonists were able to induce an increase in Fos and Jun protein expression in pentylenetetrazole (25 mg/kg i.p.) treated mice whilst the GABA(B) receptor agonist R-baclofen (2 or 6 mg/kg) attenuated the expression of Fos and Jun protein, at cortical and limbic structures. In order to study the persistence of changes induced by pentylenetetrazole kindling, different groups of mice were rechallenged with a kindling stimulus 15 or 30 days after withdrawal from the last injection of vehicle+pentylenetetrazole, R-baclofen+pentylenetetrazole or GABA(B) receptor antagonists+pentylenetetrazole. The groups receiving GABA(B) receptor antagonists+pentylenetetrazole showed a higher incidence of seizures following the kindling stimulus than mice receiving vehicle+pentylenetetrazole whilst animals treated with R-baclofen were protected from the kindling stimulus. The different effects observed following repeated treatment with the GABA(B) receptor agonist and antagonist used revealed that GABA(B) receptors are able to affect the development of the epileptic kindling state induced by pentylenetetrazole.


Assuntos
Modelos Animais de Doenças , Epilepsia/tratamento farmacológico , Antagonistas GABAérgicos/farmacologia , Antagonistas de Receptores de GABA-B , Excitação Neurológica/efeitos dos fármacos , Animais , Córtex Cerebral/efeitos dos fármacos , Córtex Cerebral/metabolismo , Convulsivantes , Epilepsia/induzido quimicamente , Epilepsia/fisiopatologia , Antagonistas GABAérgicos/uso terapêutico , Excitação Neurológica/fisiologia , Masculino , Camundongos , Pentilenotetrazol , Proteínas Proto-Oncogênicas c-fos/efeitos dos fármacos , Proteínas Proto-Oncogênicas c-fos/metabolismo , Proteínas Proto-Oncogênicas c-jun/efeitos dos fármacos , Proteínas Proto-Oncogênicas c-jun/metabolismo , Receptores de GABA-B/metabolismo
13.
Pharmacol Toxicol ; 83(1): 1-7, 1998 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-9764419

RESUMO

The present article reviews the results of experimental studies on paraquat neurotoxicity, started by our group several years ago--when clinical and experimental reports had increased the interest for the possibility that environmental chemicals, including paraquat, may be related to the development of Parkinson's disease-, and which are still continuing since paraquat appears to be a promising tool to study the mechanisms of neuronal cell death in vivo. Our observations have demonstrated that paraquat causes evident neurotoxic effects after intracerebroventricular or intracerebral injection in experimental animals; however, it seems that the herbicide does not exibit a selective neurotoxicity towards the dopaminergic nigro-striatal system since potent behavioural and electrocortical changes are induced by paraquat after injection in brain areas other than the substantia nigra and caudate nucleus. By studying the mechanisms through which paraquat induces neurotoxic effects in vivo, it was shown that either free radical production and activation of cholinergic and glutamatergic transmission may be regarded as related events which play a crucial role in paraquat-induced neurotoxicity. In addition, it was observed that in rats paraquat penetrates the blood-brain barrier following systemic administration to give rise to a differential brain regional distribution; the latter observation rises some concern over the hazard of paraquat as a potential environmental neurotoxin. Indeed, paraquat, administered systemically in rats produces behavioural excitation and brain damage. The brain damage appears to be selective for the pyriform cortex and this does not seem to be strictly related to the high concentrations reached by the herbicide in this area but to the higher vulnerability of this cortical area to the enhanced cholinergic transmission. The recent observation that paraquat, injected into the rat hippocampus, induces the expression of apoptotic neuronal cell death, appears of valuable interest also with a view to paraquat as an useful experimental model in the development of neuroprotective drugs able to block the molecular events which, once activated, are responsible for the induction of neuronal cell death.


Assuntos
Encéfalo/efeitos dos fármacos , Herbicidas/toxicidade , Neurônios/efeitos dos fármacos , Paraquat/toxicidade , Animais , Comportamento Animal/efeitos dos fármacos , Barreira Hematoencefálica/efeitos dos fármacos , Encéfalo/fisiopatologia , Morte Celular , Modelos Animais de Doenças , Injeções Intraventriculares , Ratos
14.
Biochem Pharmacol ; 56(2): 153-6, 1998 Jul 15.
Artigo em Inglês | MEDLINE | ID: mdl-9698067

RESUMO

The neuronal loss often described at post-mortem in the brain neocortex of patients suffering from AIDS has been proposed to be responsible for the development of the AIDS dementia complex. Neuroinvasive strains of the HIV virus infect macrophages, microglial cells, and multinucleated giant cells, but not neurones. Processing of the virus by cells of the myelomonocytic lineage yields viral products known to initiate a complex network of events that may lead to the death of neurones and to the development of AIDS-associated neurological syndrome. The HIV-1 coat protein gp120, in particular, has been proposed as a likely etiologic agent of the described neuronal loss because it causes the death of neurones in culture. More recently, it has been shown that brain cortical cell death caused in rats by intracerebroventricular injection of gp120 occurs via apoptosis. This observation broadens our knowledge of the pathophysiology of the reported neuronal cell loss and opens a new avenue of experimental research for the development of novel therapeutic strategies for the treatment of patients suffering from AIDS-associated neurological syndrome.


Assuntos
Encéfalo/metabolismo , Proteína gp120 do Envelope de HIV/metabolismo , Interleucina-1/metabolismo , Fatores de Crescimento Neural/metabolismo , Óxido Nítrico/metabolismo , Transdução de Sinais , Complexo AIDS Demência/metabolismo , Complexo AIDS Demência/patologia , Animais , Apoptose , Encéfalo/patologia , Encéfalo/virologia , HIV-1/isolamento & purificação , HIV-1/metabolismo , Humanos , Técnicas In Vitro , Ratos
15.
Br J Pharmacol ; 124(4): 742-6, 1998 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-9690866

RESUMO

1. The role of the L-arginine-nitric oxide (NO) pathway on the formation of prostaglandin E2 (PGE2) by human cultured astroglial cells incubated with interleukin-1beta (IL-1beta) and tumour necrosis factor-alpha (TNF-alpha) was investigated. 2. Incubation of T 67 astroglial cell line with IL-beta (10 ng ml(-1)) and TNF-alpha (500 u ml(-1)) produced a significant (P<0.05) increase of both nitrite (the breakdown product of NO), cyclic GMP and PGE2 levels in cell supernatants. N omega-nitro-L-arginine methyl ester (L-NAME; 20-300 microM), an inhibitor of NO synthase (NOS), inhibited the increase of cyclic GMP and nitrite levels found in supernatants of cytokine-treated astroglial cells and reduced the release of PGE2. The latter effect showed that the enhanced arachidonic acid (AA) metabolism subsequent to stimulation of astroglial cells with IL-1beta and TNF-alpha was, at least in part, induced by NO. This occurred also when sodium nitroprusside (SNP; 120 microM), an NO donor, was incubated with astroglial cells, an effect antagonized by oxyhaemoglobin (OxyHb; 10 microM). 3. The inhibition elicited by L-NAME on PGE2-release by cytokine-treated astroglial cells was reversed by adding AA (40 microM), showing that the effect of NO on cytokine-dependent PGE2 release occurred at the cyclo-oxygenase (COX) level. Furthermore, the release of PGE2 in cytokine-treated astroglial cells was inhibited by indomethacin (10 microM), a COX inhibitor as well as by preincubating cells with dexamethasone (20 microM), an inhibitor of inducible enzymes, showing that the inducible isoform of COX (COX-2) was involved. 4. On the other hand, pretreating astroglial cells with methylene blue (MB; 10 microM), an inhibitor of NO biological activity acting at the guanylate cyclase level, failed to affect PGE2 release in cytokine-treated astroglial cells, leading to the conclusion that cyclic GMP changes related to NO formation are not involved in the generation of AA metabolites. 5. The present experiments demonstrated that the release of PGE2 by astroglial cells pretreated with IL-1beta and TNF-alpha is due to enhanced COX-2 activity via activation of the L-arginine-NO pathway, and this may be relevant to the understanding of the pathophysiological mechanisms underlying neuroimmune disorders.


Assuntos
Astrócitos/metabolismo , Dinoprostona/metabolismo , Interleucina-1/metabolismo , Isoenzimas/biossíntese , Óxido Nítrico/metabolismo , Prostaglandina-Endoperóxido Sintases/biossíntese , Fator de Necrose Tumoral alfa/metabolismo , Astrócitos/citologia , Astrócitos/efeitos dos fármacos , Astrócitos/enzimologia , Linhagem Celular , GMP Cíclico/metabolismo , Ciclo-Oxigenase 2 , Inibidores de Ciclo-Oxigenase 2 , Inibidores de Ciclo-Oxigenase/farmacologia , Dexametasona/farmacologia , Indução Enzimática , Inibidores Enzimáticos/farmacologia , Humanos , Proteínas de Membrana , NG-Nitroarginina Metil Éster/farmacologia , Óxido Nítrico Sintase/antagonistas & inibidores , Nitritos/metabolismo , Nitroprussiato/farmacologia
16.
Biochem Biophys Res Commun ; 246(3): 686-9, 1998 May 29.
Artigo em Inglês | MEDLINE | ID: mdl-9618273

RESUMO

The HIV-1 envelope protein gp120 engenders Ca(2+)-mediated, excitotoxic damage of rodent neuronal and human neuroblastoma cells in culture. Here we report that human CHP100 neuroblastoma cells undergo early peroxidation of membrane lipids following a brief exposure to gp120. This effect is prevented by preincubating cell cultures with the 21-aminosteroid U-74389G, an inhibitor of membrane lipid peroxidation, which also rescues neuroblastoma cultures from gp120-induced cell death; conversely, no protection from cell death is observed when the 21-aminosteroid is added to neuroblastoma cultures after the induction of membrane lipid peroxidation by gp120. These data indicate that membrane lipid peroxidation has a causative role in the expression of cell death produced by the viral protein.


Assuntos
Morte Celular , Proteína gp120 do Envelope de HIV/toxicidade , HIV-1 , Peroxidação de Lipídeos , Lipídeos de Membrana/metabolismo , Neurônios/efeitos dos fármacos , Antioxidantes/farmacologia , Cálcio/metabolismo , Humanos , Neuroblastoma , Pregnatrienos/farmacologia , Receptores de N-Metil-D-Aspartato/metabolismo , Células Tumorais Cultivadas
17.
Exp Neurol ; 149(2): 349-55, 1998 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-9500967

RESUMO

Administration of tacrine (5 mg/kg i.p.), an anticholinesterase agent, in rats pretreated (24 h beforehand) with lithium chloride (LiCl; 12 mEq/kg i.p.) enhances the expression of neuronal nitric oxide (NO) synthase (NOS), increases NO, and causes seizures and hippocampal damage. Here we report immunohistochemistry evidence showing that in rat LiCl and tacrine enhance the expression of cyclooxygenase type 2 (COX-2) enzyme protein in the dorsal hippocampus and elevate brain PGE2 content during the preconvulsive period. The latter effect, but not enhanced COX-2 expression, is inhibited by previous (30 min before tacrine) administration of N omega-nitro-L-arginine-methyl ester (L-NAME; 10 mg/kg i.p.), an inhibitor of NO synthesis, thus implicating NO in the mechanism of stimulation of COX activity leading to elevation of brain PGE2 content. Indomethacin (10 mg/kg given i.p. 30 min before tacrine), an inhibitor of COX activity, prevented brain PGE2 elevation and abolished the expression of seizures and hippocampal damage thus supporting a role for this metabolite of the arachidonic acid cascade in the mechanisms of LiCl and tacrine-evoked neurotoxicity in rat.


Assuntos
Dinoprostona/metabolismo , Hipocampo/efeitos dos fármacos , Indometacina/farmacologia , Cloreto de Lítio/toxicidade , NG-Nitroarginina Metil Éster/farmacologia , Neurônios/fisiologia , Óxido Nítrico Sintase/biossíntese , Convulsões/prevenção & controle , Tacrina/toxicidade , Animais , Inibidores da Colinesterase/toxicidade , Ciclo-Oxigenase 2 , Indução Enzimática/efeitos dos fármacos , Hipocampo/metabolismo , Hipocampo/patologia , Isoenzimas/metabolismo , Cinética , Masculino , Neurônios/efeitos dos fármacos , Neurônios/patologia , Prostaglandina-Endoperóxido Sintases/metabolismo , Ratos , Ratos Wistar , Convulsões/induzido quimicamente , Convulsões/metabolismo
18.
Biochem Biophys Res Commun ; 238(3): 916-9, 1997 Sep 29.
Artigo em Inglês | MEDLINE | ID: mdl-9325192

RESUMO

The effect of 0, 30, 60, 120, 240, 360 min hypoxia on the release of NO and PGE2 was investigated in human cultured astroglial cells. Exposure of astroglial cells to hypoxic injury produced a dose-dependent increase of the nitrite (the breakdown product of NO) level in the cell supernatant. In addition, a significant activation of the inducible isoform of NO synthase was seen, demonstrating that the enhancement on NO release produced by hypoxic injury was related to an increased biosynthesis of NO-generating enzyme(s). This effect was strongly antagonised by pretreating cells with dexamethasone (20 microM). The increase in NO release by hypoxic astroglial cells was accompanied by sustained release of PGE2, which was antagonised by the cyclooxygenase inhibitor indomethacin (10 microM), and partially attenuated by L-NAME (100 microM), a nitric oxide synthase inhibitor, showing that the release of PGE2 was driven by NO. Finally, inducible NOS activity elicited by hypoxic injury, was antagonised by incubating astroglial cells with antibodies directed against type 2 receptor for IL1 beta. In conclusion, hypoxia stimulates cytokine network in astroglial cells leading to enhanced release of NO and prostanoids and this may represent a key mechanism in cerebral blood flow disturbances.


Assuntos
Astrócitos/metabolismo , Astrócitos/fisiologia , Dinoprostona/metabolismo , Interleucina-1/fisiologia , Óxido Nítrico/metabolismo , Animais , Astrócitos/enzimologia , Astrocitoma , Hipóxia Celular/efeitos dos fármacos , Sistema Livre de Células , Humanos , Indometacina/farmacologia , Óxido Nítrico Sintase/metabolismo , Prostaglandina-Endoperóxido Sintases/metabolismo , Células Tumorais Cultivadas
19.
Life Sci ; 60(8): 555-64, 1997.
Artigo em Inglês | MEDLINE | ID: mdl-9042390

RESUMO

The behavioural and electrocortical (ECoG) effects of human recombinant tumor necrosis factor-alpha (hrTNF-alpha) and various forms of interleukin-1 (IL-1) microinjected into the locus coeruleus (LC) of rats were studied. IL-1 induced a typical, dose-dependent, behavioural sedation and/or sleep which was associated with ECoG synchronization. IL-1 beta appeared more potent than IL-1 alpha. During sleep induced by the various forms of IL-1 a dose-dependent increase in total voltage power (0.25-16 Hz) as well as in the 3-6, 6-9 and sometimes 0.25-3 Hz frequency bands was observed. The behavioural and ECoG effects of IL-1 beta were blocked in rats pretreated with anti-IL-1 monoclonal antibodies. The microinjection of hrTNF-alpha into the LC produced a typical pattern characterized by a first short lasting (20-30 min) phase of behavioural arousal and ECoG desynchronization, followed by a longer lasting (45-80 min) phase of behavioural sedation and/or sleep and ECoG synchronization characterized by an increase in total voltage power as well as in the 3-6, 6-9 and sometimes 0.25-3 Hz frequency bands. The behavioural and ECoG effects of hrTNF-alpha were antagonized by a pretreatment (15 min before) with specific anti-TNF-alpha polyclonal antibodies. In addition, a pretreatment with anti-IL-1 receptor monoclonal antibodies was unable to significantly affect the stimulation of behaviour and ECoG desynchronization effects elicited by hrTNF-alpha whilst the same pretreatment completely prevent the sedative and ECoG synchronizing phase elicited by the microinjection of hrTNF-alpha into the LC. These results are consisted with the hypothesis that the sedative and/or soporific behavioural and ECoG changes of hrTNF-alpha are mediated, at LC level, through a local IL-1 release.


Assuntos
Interleucina-1/farmacologia , Locus Cerúleo , Atividade Motora/efeitos dos fármacos , Fator de Necrose Tumoral alfa/farmacologia , Animais , Córtex Cerebral/efeitos dos fármacos , Córtex Cerebral/fisiologia , Eletrocardiografia , Interleucina-1/administração & dosagem , Masculino , Microinjeções , Ratos , Ratos Wistar , Proteínas Recombinantes/administração & dosagem , Proteínas Recombinantes/farmacologia , Fator de Necrose Tumoral alfa/administração & dosagem
20.
Angiology ; 47(2): 189-96, 1996 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-8595015

RESUMO

The authors have focused this study on the emergence of subacute ventricular free wall rupture in a seventy-six-year-old patient admitted to hospital for inferior acute myocardial infarction. After six days he showed clinical signs of bradycardia and hypotension evolving to electromechanical dissociation. Given an adequate pharmacologic therapy, the patient was submitted to echocardiography, which was believed to be consistent with myocardial rupture, showing a moderate to large pericardial effusion. Pericardiocentesis of 150 mL of bloody fluid resulted in a further improvement in his hemodynamics. The patient underwent cardiac surgery with repair of the myocardial rupture through a large diaphragmatic infarction by a Dacron polyester fiber graft and pacemaker placement. In conclusion the authors confirm the relevant role of clinical data such as persistent chest pain and hemodynamic instability and the value of echocardiography in identifying subacute myocardial free wall rupture after an episode of acute myocardial infarction.


Assuntos
Ruptura Cardíaca Pós-Infarto/diagnóstico , Idoso , Bradicardia/etiologia , Ecocardiografia , Eletrocardiografia , Humanos , Hipotensão/etiologia , Masculino
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