RESUMO
Mast cells (MCs) are important effectors in allergic reactions since they produce a number of pre-formed and de novo synthesized pro-inflammatory compounds in response to the high affinity IgE receptor (FcεRI) crosslinking. IgE/Antigen-dependent degranulation and cytokine synthesis in MCs have been recognized as relevant pharmacological targets for the control of deleterious inflammatory reactions. Despite the relevance of allergic diseases worldwide, efficient pharmacological control of mast cell degranulation has been elusive. In this work, the xanthone jacareubin was isolated from the heartwood of the tropical tree Callophyllum brasilense, and its tridimensional structure was determined for the first time by X-ray diffraction. Also, its effects on the main activation parameters of bone marrow-derived mast cells (BMMCs) were evaluated. Jacareubin inhibited IgE/Ag-induced degranulation in a dose-response manner with an IC50â¯=â¯46â¯nM. It also blocked extracellular calcium influx triggered by IgE/Ag complexes and by the SERCA ATPase inhibitor thapsigargin (Thap). Inhibition of calcium entry correlated with a blockage on the reactive oxygen species (ROS) accumulation. Antioxidant capacity of jacareubin was higher than the showed by α-tocopherol and caffeic acid, but similar to trolox. Jacareubin shown inhibitory actions on xanthine oxidase, but not on NADPH oxidase (NOX) activities. In vivo, jacareubin inhibited passive anaphylactic reactions and TPA-induced edema in mice. Our data demonstrate that jacareubin is a potent natural compound able to inhibit anaphylactic degranualtion in mast cells by blunting FcεRI-induced calcium flux needed for secretion of granule content, and suggest that xanthones could be efficient anti-oxidant, antiallergic, and antiinflammatory molecules.
Assuntos
Anafilaxia/metabolismo , Cálcio/metabolismo , Mastócitos/metabolismo , Espécies Reativas de Oxigênio/metabolismo , Receptores de IgE/antagonistas & inibidores , Xantonas/farmacologia , Animais , Degranulação Celular/efeitos dos fármacos , Degranulação Celular/fisiologia , Células Cultivadas , Relação Dose-Resposta a Droga , Líquido Extracelular/efeitos dos fármacos , Líquido Extracelular/metabolismo , Masculino , Mastócitos/efeitos dos fármacos , Camundongos , Camundongos Endogâmicos C57BL , Difração de Raios X , Xantonas/isolamento & purificaçãoRESUMO
Ceramide accumulation in mitochondria has been associated with reperfusion damage, but the underlying mechanisms are not clearly elucidated. In this work we investigate the role of sphingomyelinases in mitochondrial ceramide accumulation, its effect on reactive oxygen species production, as well as on mitochondrial function by using the sphingomyelinase inhibitor, tricyclodecan-9-yl-xanthogenate (D609). Correlation between neutral sphingomyelinase (nSMase) activity and changes in ceramide content were performed in whole tissue and in isolated mitochondria from reperfused hearts. Overall results demonstrated that D609 treatment attenuates cardiac dysfuncion, mitochondrial injury and oxidative stress. Ceramide was accumulated in mitochondria, but not in the microsomal fraction of the ischemic-reperfused (I/R) group. In close association, the activity of nSMase increased, whereas glutathione (GSH) levels diminished in mitochondria after reperfusion. On the other hand, reduction of ceramide levels in mitochondria from I/R+D609 hearts correlated with diminished nSMase activity, coupling of oxidative phosphorylation and with mitochondrial integrity maintenance. These results suggest that mitochondrial nSMase activity contributes to compartmentation and further accumulation of ceramide in mitochondria, deregulating their function during reperfusion.
Assuntos
Ceramidas/metabolismo , Mitocôndrias Cardíacas/metabolismo , Proteínas Mitocondriais/metabolismo , Traumatismo por Reperfusão Miocárdica/metabolismo , Fosforilação Oxidativa , Esfingomielina Fosfodiesterase/metabolismo , Animais , Hidrocarbonetos Aromáticos com Pontes/farmacologia , Glutationa/metabolismo , Proteínas Mitocondriais/antagonistas & inibidores , Traumatismo por Reperfusão Miocárdica/patologia , Norbornanos , Ratos , Esfingomielina Fosfodiesterase/antagonistas & inibidores , Tiocarbamatos , Tionas/farmacologiaRESUMO
Oxidative/nitrosative stress is involved in NMDA receptor-mediated excitotoxic brain damage produced by the glutamate analog quinolinic acid. The purpose of this work was to study a possible role of peroxynitrite, a reactive oxygen/nitrogen species, in the course of excitotoxic events evoked by quinolinic acid in the brain. The effects of Fe(TPPS) (5,10,15,20-tetrakis (4-sulfonatophenyl)porphyrinate iron (III)), an iron porphyrinate and putative peroxynitrite decomposition catalyst, were tested on lipid peroxidation and mitochondrial function in brain synaptic vesicles exposed to quinolinic acid, as well as on peroxynitrite formation, nitric oxide synthase and superoxide dismutase activities, lipid peroxidation, caspase-3-like activation, DNA fragmentation, and GABA levels in striatal tissue from rats lesioned by quinolinic acid. Circling behavior was also evaluated. Increasing concentrations of Fe(TPPS) reduced lipid peroxidation and mitochondrial dysfunction induced by quinolinic acid (100 microM) in synaptic vesicles in a concentration-dependent manner (10-800 microM). In addition, Fe(TPPS) (10 mg/kg, i.p.) administered 2 h before the striatal lesions, prevented the formation of peroxynitrite, the increased nitric oxide synthase activity, the decreased superoxide dismutase activity and the increased lipid peroxidation induced by quinolinic acid (240 nmol/microl) 120 min after the toxin infusion. Enhanced caspase-3-like activity and DNA fragmentation were also reduced by the porphyrinate 24 h after the injection of the excitotoxin. Circling behavior from quinolinic acid-treated rats was abolished by Fe(TPPS) six days after quinolinic acid injection, while the striatal levels of GABA, measured one day later, were partially recovered. The protective effects that Fe(TPPS) exerted on quinolinic acid-induced lipid peroxidation and mitochondrial dysfunction in synaptic vesicles suggest a primary action of the porphyrinate as an antioxidant molecule. In vivo findings suggest that the early production of peroxynitrite, altogether with the enhanced risk of superoxide anion (O2*-) and nitric oxide formation (its precursors) induced by quinolinic acid in the striatum, are attenuated by Fe(TPPS) through a recovery in the basal activities of nitric oxide synthase and superoxide dismutase. The porphyrinate-mediated reduction in DNA fragmentation simultaneous to the decrease in caspase-3-like activation from quinolinic acid-lesioned rats suggests a prevention in the risk of peroxynitrite-mediated apoptotic events during the course of excitotoxic damage in the striatum. In summary, the protective effects that Fe(TPPS) exhibited both under in vitro and in vivo conditions support an active role of peroxynitrite and its precursors in the pattern of brain damage elicited by excitotoxic events in the experimental model of Huntington's disease. The neuroprotective mechanisms of Fe(TPPS) are discussed.
Assuntos
Lesões Encefálicas/metabolismo , Doença de Huntington/prevenção & controle , Ácido Peroxinitroso/metabolismo , Porfirinas/uso terapêutico , Radiossensibilizantes/uso terapêutico , Análise de Variância , Animais , Comportamento Animal , Southern Blotting/métodos , Lesões Encefálicas/complicações , Caspase 3 , Caspases/metabolismo , Cromatografia Líquida de Alta Pressão/métodos , Corpo Estriado/efeitos dos fármacos , Corpo Estriado/metabolismo , Modelos Animais de Doenças , Relação Dose-Resposta a Droga , Interações Medicamentosas , Eletroforese em Gel de Ágar/métodos , Doença de Huntington/etiologia , Peroxidação de Lipídeos/efeitos dos fármacos , Peroxidação de Lipídeos/fisiologia , Masculino , Mitocôndrias/fisiologia , Atividade Motora/efeitos dos fármacos , Atividade Motora/fisiologia , Óxido Nítrico Sintase/metabolismo , Ácidos Quinolínicos/farmacologia , Ratos , Ratos Wistar , Teste de Desempenho do Rota-Rod/métodos , Superóxido Dismutase/metabolismo , Vesículas Sinápticas/metabolismo , Sinaptossomos/fisiologia , Tirosina/análogos & derivados , Tirosina/metabolismo , Ácido gama-Aminobutírico/metabolismoRESUMO
Reactive oxygen species are involved in gentamicin (GM) nephrotoxicity, and garlic is effective in preventing or ameliorating oxidative stress. Therefore, the effect of garlic on GM nephrotoxicity was investigated in this work. Four groups of rats were studied: (i) fed normal diet (CT), (ii) treated with GM (GM), (iii) fed 2% garlic diet (GA), and (iv) treated with GM and 2% garlic diet (GM + GA). Rats were placed in metabolic cages and GM nephrotoxicity was induced by injections of GM (75 mg/kg every 12 h) for 6 d. Lipoperoxidation and enzyme determinations were made in renal cortex on day 7. GM nephrotoxicity was made evident on day 7 by (i) tubular histological damage, (ii) enhanced BUN and urinary excretion of N-acetyl-beta-D-glucosaminidase, and (iii) decreased creatinine clearance. These alterations were prevented or ameliorated in GM + GA group. The rise in lipoperoxidation and the decrease in Mn-SOD and glutathione peroxidase (GPx) activities observed in the GM group, were prevented in the GM + GA group. Cu, Zn-SOD activity and Mn-SOD and Cu,Zn-SOD content did not change. CAT activity and content decreased in the GM, GA, and GM + GA groups. CAT mRNA levels decreased in the GM group. The protective effect of garlic is associated with the prevention of the decrease of Mn-SOD and GPx activities and with the rise of lipoperoxidation in renal cortex.
Assuntos
Catalase/metabolismo , Alho , Gentamicinas/toxicidade , Glutationa Peroxidase/metabolismo , Rim/efeitos dos fármacos , Rim/enzimologia , Peroxidação de Lipídeos/efeitos dos fármacos , Plantas Medicinais , Superóxido Dismutase/genética , Acetilglucosaminidase/urina , Animais , Nitrogênio da Ureia Sanguínea , Catalase/genética , Dieta , Regulação Enzimológica da Expressão Gênica/efeitos dos fármacos , Rim/patologia , Córtex Renal/efeitos dos fármacos , Córtex Renal/patologia , Masculino , Estresse Oxidativo , Proteinúria , Ratos , Ratos Wistar , Reação em Cadeia da Polimerase Via Transcriptase Reversa , Superóxido Dismutase/metabolismoRESUMO
1. The concentration of renin and angiotensinogen (Ao) and the activity of angiotensin I-converting enzyme (ACE) was measured in the ascites fluid of nephrotic rats obtained 8 days after puromycin aminonucleoside (PAN) injection. 2. Ascites fluid, serum and urine proteins of these rats were analysed by sodium dodecyl sulphate-polyacrylamide gel electrophoresis (SDS-PAGE). 3. Renin, Ao and ACE were found in the ascites fluid and the percentage of the ratio ascites fluid/(plasma or serum) ranged from 5.9 to 9.9%. The electrophoretic analysis revealed that the ascites fluid contained low (Mr < 66 kDa) and high (Mr < 66 kDa) molecular weight proteins. Albumin and six proteins higher than 66 kDa were present both in the ascites fluid and in serum from nephrotic rats. 4. Data from the study suggest that some proteins in the ascites fluid, including renin, Ao and ACE, come from the plasma. It is possible that the loss of renin, Ao and ACE to the ascites fluid may be playing a role in the metabolic alterations of these three proteins in PAN-nephrotic rats.