RESUMO
In the present study, we investigated the cardioactive glycosides oleandrin and ouabain, and compared them to digoxin in a model of cardiotoxicity induced by doxorubicin. Adult rats were distributed into four experimental groups. Each group was challenged with a single intraperitoneal application of doxorubicin at a dose of 12 mg/kg. Then, they were treated with saline solution and the glycosides oleandrin, ouabain, and digoxin at a dose of 50 µg/kg, for 7 days. They underwent echocardiography, electrocardiography, hematologic, biochemical tests, and microscopic evaluation of the heart. All animals presented congestive heart failure, which was verified by a reduction in the ejection fraction. Oleandrin and digoxin were able to significantly reduce (p < 0.05) the eccentric remodeling caused by doxorubicin. Oleandrin and digoxin were significantly lower (p < 0.05) than the control group in maintaining systolic volume and left ventricular volume in diastole. Other parameters evaluated did not show significant statistical differences. All animals showed an increase in erythrocyte count, and an increase in the duration of the QRS complex on the ECG and myocardial necrosis at the histopathological analysis. It is concluded that the glycosides oleandrin, ouabain, and digoxin in the used dosage do not present therapeutic potential for the treatment of congestive heart failure caused by doxorubicin.
Assuntos
Cardenolídeos/farmacologia , Glicosídeos Cardíacos/farmacologia , Cardiotônicos/farmacologia , Digoxina/farmacologia , Insuficiência Cardíaca/tratamento farmacológico , Ouabaína/farmacologia , Volume Sistólico/efeitos dos fármacos , Função Ventricular Esquerda/efeitos dos fármacos , Remodelação Ventricular/efeitos dos fármacos , Animais , Cardenolídeos/toxicidade , Glicosídeos Cardíacos/toxicidade , Cardiotônicos/toxicidade , Cardiotoxicidade , Digoxina/toxicidade , Modelos Animais de Doenças , Doxorrubicina , Insuficiência Cardíaca/induzido quimicamente , Insuficiência Cardíaca/diagnóstico por imagem , Insuficiência Cardíaca/fisiopatologia , Ouabaína/toxicidade , Ratos Wistar , Recuperação de Função FisiológicaRESUMO
The aim of this study was to evaluate the comparative effects of CGs on heart physiology. Twenty-eight Wistar rats were distributed into four groups (n = 7), control group received NaCl 0.9% every 24 h for 21 days; treated groups received respectively 50 µg/kg of digoxin (DIG), ouabain (OUA) and oleandrin (OLE) every 24 h for 21 days. Serial ECGs were performed, as well as serum levels of creatinine kinase (CK), its MB fraction, troponin I (cTnI), calcium (Ca2+) and lactic dehydrogenase (LDH). Heart tissue was processed for histology, scanning electron microscopy and Western blot analysis for cTnI, brain natriuretic peptide (BNP), sodium potassium pump alpha-1 and alpha-2. Ventricle samples were also analyzed for thiobarbituric acid reactive substances and antioxidant enzymes (SOD, GPX, and CAT). ECGs showed decrease in QT and progressive shortening of QRS. No arrhythmias were observed. No significant differences were associated with CGs treatment and serum levels of CK, CK-MB, and cTnI. Only oleandrin increased LDH levels. Histological analysis showed degenerative changes and only oleandrin promoted moderate focal necrosis of cardiomyocytes. Scanning microscopy also confirmed the greatest effect of oleandrin, with rupture and shortening of cardiac fibers. The expression of troponin I and alpha-1 isoform were not altered, however, the protein levels of BNP and alpha-2 were higher in the groups that received oleandrin and ouabain in relation to the digoxin group. All GCs affected the production of ROS, without causing lipid peroxidation, through the activation of different antioxidant pathways. It is concluded that the administration of digoxin, ouabain, and oleandrin at 50 µg/kg for 21 days caused cardiovascular damage that represent an important limitation into its future use in heart failure and antineoplastic therapy.
Assuntos
Cardenolídeos/toxicidade , Digoxina/toxicidade , Cardiopatias/induzido quimicamente , Coração/efeitos dos fármacos , Miócitos Cardíacos/efeitos dos fármacos , Ouabaína/toxicidade , Animais , Antioxidantes/metabolismo , Cardiotoxicidade , Relação Dose-Resposta a Droga , Coração/fisiopatologia , Cardiopatias/metabolismo , Cardiopatias/patologia , Cardiopatias/fisiopatologia , Frequência Cardíaca/efeitos dos fármacos , Masculino , Miócitos Cardíacos/metabolismo , Miócitos Cardíacos/ultraestrutura , Necrose , Estresse Oxidativo/efeitos dos fármacos , Ratos Wistar , Espécies Reativas de Oxigênio/metabolismo , Remodelação Ventricular/efeitos dos fármacosRESUMO
Studies have revealed alterations in mitochondrial complexes in the brains of bipolar patients. However, few studies have examined changes in the enzymes of the tricarboxylic acid cycle. Several preclinical studies have suggested that histone deacetylase inhibitors may have antimanic effects. The present study aims to investigate the effects of lithium, valproate and sodium butyrate, a histone deacetylase inhibitor, on the activity of tricarboxylic acid cycle enzymes in the brains of rats subjected to an animal model of mania induced by ouabain. Wistar rats received a single intracerebroventricular injection of ouabain or cerebrospinal fluid. Starting on the day following the intracerebroventricular injection, the rats were treated for 7days with intraperitoneal injections of saline, lithium, valproate or sodium butyrate. Risk-taking behavior, locomotor and exploratory activities were measured using the open-field test. Citrate synthase, succinate dehydrogenase, and malate dehydrogenase were examined in the frontal cortex and hippocampus. All treatments reversed ouabain-related risk-taking behavior and hyperactivity in the open-field test. Ouabain inhibited tricarboxylic acid cycle enzymes in the brain, and valproate and sodium butyrate but not lithium reversed this ouabain-induced dysfunction. Thus, protecting the tricarboxylic acid cycle may contribute to the therapeutic effects of histone deacetylase inhibitors.
Assuntos
Antimaníacos/farmacologia , Transtorno Bipolar/tratamento farmacológico , Encéfalo/efeitos dos fármacos , Inibidores de Histona Desacetilases/farmacologia , Animais , Comportamento Animal/efeitos dos fármacos , Transtorno Bipolar/metabolismo , Transtorno Bipolar/psicologia , Encéfalo/metabolismo , Ácido Butírico/farmacologia , Ciclo do Ácido Cítrico/efeitos dos fármacos , Modelos Animais de Doenças , Metabolismo Energético/efeitos dos fármacos , Comportamento Exploratório/efeitos dos fármacos , Lítio/farmacologia , Masculino , Atividade Motora/efeitos dos fármacos , Ouabaína/toxicidade , Ratos , Ratos Wistar , Ácido Valproico/farmacologiaRESUMO
Bipolar Disorder (BD) is one of the most severe psychiatric disorders. Despite adequate treatment, patients continue to have recurrent mood episodes, residual symptoms, and functional impairment. Some preclinical studies have shown that histone deacetylase inhibitors may act on manic-like behaviors. Neurotrophins have been considered important mediators in the pathophysiology of BD. The present study aims to investigate the effects of lithium (Li), valproate (VPA), and sodium butyrate (SB), an HDAC inhibitor, on BDNF, NGF and GDNF in the brain of rats subjected to an animal model of mania induced by ouabain. Wistar rats received a single ICV injection of ouabain or artificial cerebrospinal fluid. From the day following ICV injection, the rats were treated for 6 days with intraperitoneal injections of saline, Li, VPA or SB twice a day. In the 7th day after ouabain injection, locomotor activity was measured using the open-field test. The BDNF, NGF and GDNF levels were measured in the hippocampus and frontal cortex by sandwich-ELISA. Li, VPA or SB treatments reversed ouabain-related manic-like behavior. Ouabain decreased BDNF, NGF and GDNF levels in hippocampus and frontal cortex of rats. The treatment with Li, VPA or SB reversed these impairment induced by ouabain. In addition, Li, VPA and SB per se increased NGF and GDNF levels in hippocampus of rats. Our data support the notion that neurotrophic factors play a role in BD and in the mechanisms of the action of Li, VPA and SB.
Assuntos
Antimaníacos/farmacologia , Transtorno Bipolar/tratamento farmacológico , Fator Neurotrófico Derivado do Encéfalo/metabolismo , Ácido Butírico/farmacologia , Fator Neurotrófico Derivado de Linhagem de Célula Glial/metabolismo , Locomoção/efeitos dos fármacos , Fator de Crescimento Neural/metabolismo , Afeto/efeitos dos fármacos , Animais , Transtorno Bipolar/induzido quimicamente , Transtorno Bipolar/metabolismo , Transtorno Bipolar/psicologia , Modelos Animais de Doenças , Hipocampo/efeitos dos fármacos , Hipocampo/metabolismo , Antagonistas dos Receptores Histamínicos/farmacologia , Compostos de Lítio/farmacologia , Masculino , Atividade Motora/efeitos dos fármacos , Ouabaína/toxicidade , Córtex Pré-Frontal/efeitos dos fármacos , Córtex Pré-Frontal/metabolismo , Ratos , Ratos Wistar , Resultado do Tratamento , Ácido Valproico/farmacologiaRESUMO
BACKGROUND: Digitalis-induced Na(+) accumulation results in an increase in Ca(2+)(i) via the Na(+)/Ca(2+) exchanger, leading to enhanced sarcoplasmic reticulum (SR) Ca(2+) load, responsible for the positive inotropic and toxic arrhythmogenic effects of glycosides. A digitalis-induced increase in Ca(2+)(i) could also activate calcium-calmodulin kinase II (CaMKII), which has been shown to have proarrhythmic effects. Here, we investigate whether CaMKII underlies digitalis-induced arrhythmias and the subcellular mechanisms involved. METHODS AND RESULTS: In paced rat ventricular myocytes (0.5 Hz), 50 µmol/L ouabain increased contraction amplitude by 160 ± 5%. In the absence of electric stimulation, ouabain promoted spontaneous contractile activity and Ca(2+) waves. Ouabain activated CaMKII (p-CaMKII), which phosphorylated its downstream targets, phospholamban (PLN) (Thr17) and ryanodine receptor (RyR) (Ser2814). Ouabain-induced spontaneous activity was prevented by inhibiting CaMKII with 2.5 µmol/L KN93 but not by 2.5 µmol/L of the inactive analog, KN92. Similar results were obtained using the CaMKII inhibitor, autocamtide-2 related inhibitory peptide (AIP) (1 to 2.5 µmol/L), and in myocytes from transgenic mice expressing SR-targeted AIP. Consistently, CaMKII overexpression exacerbated ouabain-induced spontaneous contractile activity. Ouabain was associated with an increase in SR Ca(2+) content and Ca(2+) spark frequency, indicative of enhanced SR Ca(2+) leak. KN93 suppressed the ouabain-induced increase in Ca(2+) spark frequency without affecting SR Ca(2+) content. Similar results were obtained with digoxin. In vivo, ouabain-induced arrhythmias were prevented by KN93 and absent in SR-AIP mice. CONCLUSIONS: These results show for the first time that CaMKII mediates ouabain-induced arrhythmic/toxic effects. We suggest that CaMKII-dependent phosphorylation of the RyR, resulting in Ca(2+) leak from the SR, is the underlying mechanism involved.
Assuntos
Arritmias Cardíacas/induzido quimicamente , Sinalização do Cálcio/efeitos dos fármacos , Proteína Quinase Tipo 2 Dependente de Cálcio-Calmodulina/metabolismo , Cardiotônicos/toxicidade , Frequência Cardíaca/efeitos dos fármacos , Ventrículos do Coração/efeitos dos fármacos , Miócitos Cardíacos/efeitos dos fármacos , Ouabaína/toxicidade , Animais , Antiarrítmicos/farmacologia , Arritmias Cardíacas/diagnóstico , Arritmias Cardíacas/fisiopatologia , Arritmias Cardíacas/prevenção & controle , Benzilaminas/farmacologia , Cálcio/metabolismo , Proteínas de Ligação ao Cálcio/genética , Proteínas de Ligação ao Cálcio/metabolismo , Proteína Quinase Tipo 2 Dependente de Cálcio-Calmodulina/antagonistas & inibidores , Proteína Quinase Tipo 2 Dependente de Cálcio-Calmodulina/genética , Estimulação Cardíaca Artificial , Células Cultivadas , Eletrocardiografia , Ativação Enzimática , Ventrículos do Coração/enzimologia , Ventrículos do Coração/fisiopatologia , Camundongos , Camundongos Endogâmicos BALB C , Camundongos Transgênicos , Contração Miocárdica/efeitos dos fármacos , Miócitos Cardíacos/enzimologia , Peptídeos/genética , Peptídeos/metabolismo , Peptídeos/farmacologia , Fosforilação , Inibidores de Proteínas Quinases/farmacologia , Ratos , Ratos Wistar , Canal de Liberação de Cálcio do Receptor de Rianodina/metabolismo , Retículo Sarcoplasmático/efeitos dos fármacos , Retículo Sarcoplasmático/enzimologia , Trocador de Sódio e Cálcio/metabolismo , Sulfonamidas/farmacologia , Fatores de Tempo , TransfecçãoRESUMO
BACKGROUND/AIMS: The purpose of this study was to examine the cardiovascular effects of long-term ouabain treatment at different time points. METHODS: Systolic blood pressure (SBP) was measured by tail-cuff method in male Wistar rats treated with ouabain (approx. 8.0 µg·day(-1)) or vehicle for 5, 10 and 20 weeks. Afterwards, vascular function was assessed in mesenteric resistance arteries (MRA) using a wire myograph. ROS production and COX-1 and COX-2, TNF-α, and IL-6 protein expression were investigated. RESULTS: SBP was increased by ouabain treatment up to the 6th week and remained stable until the 20th week. However, noradrenaline-induced contraction increased only in MRA in rats treated with ouabain for 20 weeks. NOS inhibition and endothelium removal increased the noradrenaline response, but to a smaller magnitude in MRA in the ouabain group. Moreover, inhibition of COX-2 or incubation with superoxide dismutase restores noradrenaline-induced contraction in the 20-week ouabain group to control levels. ROS production as well as COX-2, IL-6 and TNF-α protein expression increased in MRA in this group. CONCLUSION: Although ouabain treatment induced hypertension in all groups, a larger noradrenaline induced contraction was observed over 20 weeks of treatment. This vascular dysfunction was related to COX-2-derived prostanoids and oxidative stress, increased pro- inflammatory cytokines and reduced NO bioavailability.
Assuntos
Artérias Mesentéricas/efeitos dos fármacos , Ouabaína/toxicidade , Animais , Ciclo-Oxigenase 2/fisiologia , Endotélio Vascular/fisiologia , Hipertensão/induzido quimicamente , Masculino , Artérias Mesentéricas/fisiologia , Óxido Nítrico/fisiologia , Ratos , Ratos Wistar , Espécies Reativas de Oxigênio/metabolismo , Superóxidos/metabolismo , Sístole/efeitos dos fármacos , Resistência Vascular , Vasoconstrição/efeitos dos fármacosRESUMO
OBJECTIVE: Bipolar disorder (BD) is a chronic, prevalent, and highly debilitating psychiatric illness. Folic acid has been shown to have antidepressant-like effects in preclinical and clinical studies and has also been suggested to play a role in BD. The present work investigates the therapeutic value of folic acid supplementation in a preclinical animal model of mania induced by ouabain. METHODS: Male Wistar rats were treated twice daily for seven days with folic acid (10, 50, and 100 mg/kg, p.o.) or the mood stabilizer lithium chloride (LiCl) (45 mg/kg, p.o.). One day after the last dose was given, the animals received an i.c.v. injection of ouabain (10 microM), a Na(+),K(+)-ATPase-inhibiting compound. Locomotor activity was assessed in the open-field test. Thiobarbituric acid-reactive substance (TBARS) levels, glutathione peroxidase (GPx), and glutathione reductase (GR) activities were measured in the cerebral cortex and hippocampus. RESULTS: Ouabain (10 microM, i.c.v.) significantly increased motor activity in the open-field test, and seven days of pretreatment with folic acid (50 mg/kg, p.o.) or LiCl (45 mg/kg, p.o.) completely prevented this effect. Ouabain treatment elicited lipid peroxidation (increased TBARS levels) and reduced GPx activity in the hippocampus. GR activity was decreased in the cerebral cortex and hippocampus. These effects were prevented by pretreatment with folic acid and LiCl. CONCLUSIONS: Our results show that folic acid, similarly to LiCl, produces a clear antimanic action and prevents the neurochemical alterations indicative of oxidative stress in an animal model of mania.
Assuntos
Transtorno Bipolar/tratamento farmacológico , Ácido Fólico/administração & dosagem , Cloreto de Lítio/farmacologia , Atividade Motora/efeitos dos fármacos , Estresse Oxidativo/efeitos dos fármacos , Animais , Antimaníacos/farmacologia , Biomarcadores/análise , Transtorno Bipolar/induzido quimicamente , Transtorno Bipolar/fisiopatologia , Modelos Animais de Doenças , Hipocampo/efeitos dos fármacos , Hipocampo/metabolismo , Injeções Intraventriculares , Masculino , Ouabaína/toxicidade , Ratos , Ratos WistarRESUMO
Treatment of supraventricular arrhythmia includes a wide range of medical interventions. Herbal remedies are suitable alternatives to synthetic drugs due to their availability, minimal side effects and lower price. Pharmacological studies and traditional medical literature point to the cardiovascular effects of Citrus aurantium L. (Rutaceae) in many instances. In the present study we used isolated perfused AV-node of rabbit as an experimental model to determine the effect of various concentrations of essential oil of C. aurantium (0.1-0.3 v/v) on the nodal conduction time and refractoriness of an isolated rabbit AV-nodal preparations. Selective stimulation protocols were used to independently quantify AV nodal recovery, facilitation and fatigue in 18 rabbits. Our results showed concentration-dependent and rate-independent suppressive effects of essence of C. aurantium on the Wenchebach cycle length (WBCL), AV Conduction Time (AVCT) and effective and functional refractory periods (ERP & FRP). Functional properties such as facilitation and fatigue were significantly increased by this plant. Citrus aurantium plays a protective role against the toxic effects of ouabaine by increasing AV nodal conduction time and refractoriness. The above results indicated differential effects of C. aurantium on slow and fast pathways, with a dominant role on fast pathways. This research has explained the protective role of C. aurantium on ouabaine toxicity. All results indicated the potential anti-arrhythmic effects of C. aurantium in treating supraventricular tachyarrhythmia.
El tratamiento de la arritmia supraventricular incluye una amplia gama de intervenciones médicas. Los remedios herbarios son alternativas adecuadas a las drogas sintéticas debido a su disponibilidad, con escasos efectos secundarios y bajo precio. Estudios farmacológicos y la literatura médica tradicional señalan los efectos cardiovasculares de Citrus aurantium L. (Rutaceae) en muchos casos. En el presente estudio se usaron aislados perfundidos del nodo AV de conejo como modelo experimental para determinar el efecto de diferentes concentraciones de aceite esencial de C. aurantium (0,1-0,3 v/v) sobre en el tiempo de conducción nodal y refractariedad. Un protocolo de estimulación selectiva se utilizó para cuantificar de forma independiente la recuperación, la facilitación y la fatiga del nodo AV en 18 conejos. Nuestros resultados muestran efectos supresores dependientes de la concentración e independiente de la velocidad de la esencia de C. aurantium sobre la duración del ciclo Wenchebach (WBCL), tiempo de conducción AV (AVTC) y períodos refractarios eficaz y funcional (PRE y PRF). Propiedades funcionales tales como la facilitación y la fatiga se incrementaron de manera significativa por esta planta. La Citrus aurantium juega un papel protector contra los efectos tóxicos de ouabaína al incrementar el tiempo de conducción AV nodal y la refractariedad. Los resultados indican efectos diferenciales de C. aurantium sobre las vías lentas y rápidas, con un papel dominante en las vías rápidas. Esta investigación ha explicado el papel protector de C. aurantium sobre la toxicidad ouabaine. Todos los resultados indican los posibles efectos anti-arrítmicos de C. aurantium en el tratamiento de taquiarritmias supraventriculares.
Assuntos
Animais , Coelhos , Óleos Voláteis/farmacologia , Citrus/química , Nó Atrioventricular , Ouabaína/antagonistas & inibidores , Arritmias Cardíacas/tratamento farmacológico , Eletrofisiologia Cardíaca , Ouabaína/toxicidade , Preparações de Plantas/farmacologia , Fatores de TempoRESUMO
The cellular actions of ouabain are complex and involve different pathways, depending on the cell type and experimental conditions. Several studies have reported that Madin-Darby canine kidney (MDCK) cellular sensitivity to ouabain is not related to Na-K-ATPase inhibition, and others showed that some cell types, such as Ma104, are resistant to ouabain toxicity albeit their Na-K-ATPase isoforms possess high affinity for this glycoside. We describe here that the effects of ouabain and ouabagenin also diverge in MDCK and Ma104 cells, being MDCK cells more resistant to ouabagenin, while Ma104 cells are resistant to both molecules. This feature seems to correlate with induction of cell signaling, since ouabain, but not ouabagenin, induced an intense and sustained increase in tyrosine phosphorylation levels in MDCK cells. Moreover, ouabain-induced phosphorylation in Ma104 cells was approximately half than that observed in MDCK cells. The proportion between alpha and beta subunits of Na-K-ATPase was similar in MDCK cells, though Ma104 cells presented more alpha subunits, located mainly at the cytoplasm. Furthermore, a fluorescent ouabain-analog labeled mainly the cytoplasm of Ma104 cells, the opposite of that seen in MDCK cells, corroborating the results using anti-Na-K-ATPase antibodies. Hence, the results suggest that ouabain and ouabagenin differ in terms of Na-K-ATPase inhibition and cell signaling activation in MDCK cells. Additionally, MDCK and Ma104 cell lines respond differently to ouabain, perhaps due to an intrinsic ability of this glycoside to selectively reach the cytoplasm of Ma104 cells.
Assuntos
Rim/efeitos dos fármacos , Ouabaína/análogos & derivados , Ouabaína/toxicidade , Animais , Linhagem Celular/efeitos dos fármacos , Linhagem Celular/enzimologia , Linhagem Celular/metabolismo , Cães , Relação Dose-Resposta a Droga , Haplorrinos , Rim/enzimologia , Rim/metabolismo , Microscopia de Fluorescência , ATPase Trocadora de Sódio-Potássio/metabolismoRESUMO
OBJECTIVE: Hypertensive rats are more sensitive to the pressor effects of acute ouabain than normotensive rats. We analyzed the effect of chronic ouabain (approximately 8.0 microg/day, 5 weeks) treatment on the blood pressure of spontaneously hypertensive rats (SHRs) and Wistar-Kyoto rats and the contribution of vascular mechanisms. METHODS: Responses to acetylcholine and phenylephrine were analyzed in isolated tail arteries. Protein expression of endothelial nitric oxide synthase and cyclooxygenase-2 (COX-2) were also investigated. RESULTS: Ouabain treatment enhanced blood pressure only in SHRs. The pD2 for acetylcholine was decreased in arteries from SHRs compared with Wistar-Kyoto rats, and ouabain did not change this parameter. However, ouabain was able to increase the pD2 to phenylephrine in SHRs. Nitric oxide synthase inhibition with NG-nitro-L-arginine methyl ester or potassium channel blockade by tetraetylamonium increased the response to phenylephrine in SHRs, with a smaller increase in response observed in ouabain-treated SHRs. In addition, indomethacin (a COX inhibitor) and ridogrel (a thromboxane A2 synthase inhibitor and prostaglandin H2/thromboxane A2 receptor antagonist) decreased contraction to phenylephrine in tail rings from ouabain-treated SHRs. Protein expression of endothelial nitric oxide synthase was unaltered following ouabain treatment in SHRs, whereas COX-2 expression was increased. CONCLUSION: Chronic ouabain treatment further increases the raised blood pressure of SHRs. This appears to involve a vascular mechanism, related to a reduced vasodilator influence of nitric oxide and endothelium-derived hyperpolarizing factor and increased production of vasoconstrictor prostanoids by COX-2. These data suggest that the increased plasma levels of ouabain could play an important role in the maintenance of hypertension and the impairment of endothelial function.