RESUMO
Ivermectin (IVM) is a semi-synthetic antiparasitic derived from abamectin, one of the natural avermectins. The liver promotes metabolism and excretion of IVM, representing a risk of toxicity to this organ. The use of antioxidants to alleviate damage caused by chemicals has been increasingly studied. Thus, the aim of this study was to evaluate the effects of IVM on HepG2 cells to elucidate the mechanisms related to its toxicity and the possible protection provided by tetrahydrocurcumin (THC) and vitamin C. HepG2 cells were treated with IVM (1-25 µM) for 24 and 48 h. IVM was cytotoxic to HepG2 cells, denoted by a dose-dependent decrease in cell proliferation and metabolic activity. In addition, IVM induced damage to the cell membrane at all tested concentrations and for both incubation times. IVM significantly decreased the mitochondrial membrane potential from concentrations of 5 µM (24 h) and 1 µM (48 h). Additionally, IVM showed a time- and dose-dependent decrease in cellular adenosine triphosphate levels. The levels of reduced glutathione were decreased in a time- and dose-dependent manner, while IVM stimulated the production of reactive oxygen and nitrogen species (RONS) at all tested doses, reaching rates above 50% following treatment at 7.5 µM (24 h) or 5 µM (48 h). Treatment with THC (50 µM) and vitamin C (50 µM) protected against IVM-induced cytotoxicity and RONS production. These results suggest that oxidative damage is involved in IVM-induced toxicity in HepG2 cells, and that THC and vitamin C can mitigate the toxic effects caused by the compound.
RESUMO
The widespread use of pesticides in some areas where fish species such as tilapia are farmed may cause damage to the environment and affect commercial fish and therefore, human health. Water leaching with the pesticide trichlorfon, during the fumigation season in the field, can affect water quality in fish farms and consequently affect fish health. At the same time, the use of immunomodulatory compounds such as ß-glucan supplied in the diet has become widespread in fish farms as it has been shown that improves the overall immune response. The present research examines the immunomodulatory impacts observed in macrophages of Nile tilapia (Oreochromis niloticus) after being fed a diet supplemented with ß-glucan for 15 days, followed by their in vitro exposure to trichlorfon, an organophosphate pesticide, at concentrations of 100 and 500 µg mL-1 for 24 h. The results showed that ß-glucan diet improved the viability of cells exposed to trichlorfon and their antioxidant capacity. However, ß-glucan did not counteract the effects of the pesticide as for the ability to protect against bacterial infection. From the present results, it can be concluded that ß-glucan feeding exerted a protective role against oxidative damage in cells, but it was not enough to reduce the deleterious effects of trichlorfon on the microbicidal capacity of macrophages exposed to this pesticide.
Assuntos
Ciclídeos , Doenças dos Peixes , Inseticidas , Tilápia , beta-Glucanas , Humanos , Animais , Triclorfon , beta-Glucanas/farmacologia , Dieta/veterinária , Imunidade Inata , Suplementos Nutricionais/análise , Ciclídeos/fisiologia , Macrófagos , Ração Animal/análise , Doenças dos Peixes/microbiologiaRESUMO
Clomipramine, a tricyclic antidepressant used to treat depression and obsessive-compulsive disorder, has been linked to a few cases of acute hepatotoxicity. It is also recognized as a compound that hinders the functioning of mitochondria. Hence, the effects of clomipramine on mitochondria should endanger processes that are somewhat connected to energy metabolism in the liver. For this reason, the primary aim of this study was to examine how the effects of clomipramine on mitochondrial functions manifest in the intact liver. For this purpose, we used the isolated perfused rat liver, but also isolated hepatocytes and isolated mitochondria as experimental systems. According to the findings, clomipramine harmed metabolic processes and the cellular structure of the liver, especially the membrane structure. The considerable decrease in oxygen consumption in perfused livers strongly suggested that the mechanism of clomipramine toxicity involves the disruption of mitochondrial functions. Coherently, it could be observed that clomipramine inhibited both gluconeogenesis and ureagenesis, two processes that rely on ATP production within the mitochondria. Half-maximal inhibitory concentrations for gluconeogenesis and ureagenesis ranged from 36.87 µM to 59.64 µM. The levels of ATP as well as the ATP/ADP and ATP/AMP ratios were reduced, but distinctly, between the livers of fasted and fed rats. The results obtained from experiments conducted on isolated hepatocytes and isolated mitochondria unambiguously confirmed previous propositions about the effects of clomipramine on mitochondrial functions. These findings revealed at least three distinct mechanisms of action, including uncoupling of oxidative phosphorylation, inhibition of the FoF1-ATP synthase complex, and inhibition of mitochondrial electron flow. The elevation in activity of cytosolic and mitochondrial enzymes detected in the effluent perfusate from perfused livers, coupled with the increase in aminotransferase release and trypan blue uptake observed in isolated hepatocytes, provided further evidence of the hepatotoxicity of clomipramine. It can be concluded that impaired mitochondrial bioenergetics and cellular damage are important factors underlying the hepatotoxicity of clomipramine and that taking excessive amounts of clomipramine can lead to several risks including decreased ATP production, severe hypoglycemia, and potentially fatal outcomes.
Assuntos
Doença Hepática Induzida por Substâncias e Drogas , Clomipramina , Ratos , Animais , Clomipramina/toxicidade , Clomipramina/metabolismo , Metabolismo Energético , Fígado/metabolismo , Mitocôndrias/metabolismo , Trifosfato de Adenosina/metabolismo , Doença Hepática Induzida por Substâncias e Drogas/metabolismo , Mitocôndrias Hepáticas/metabolismoRESUMO
Diazinon (DZN) is an insecticide extensively used to control pests in crops and animals. However, its indicriminated use may lead to liver damage in animals and humans. This study aimed to evaluate the toxicity of DZN (25-150 µM) on human hepatoblastoma (HepG2) cells after 24 and 48 h of exposure and the role of its biotransformation on the toxicological potential. We also tested the protective effect of tetrahydrocurcumin (THC), an antioxidant agent, in the DZN-induced citotoxicity. DZN caused cytotoxicity in the HepG2 cells, inhibiting cell proliferation and reducing cell viability in a dose- and time-dependent manner. The pre-incubation of HepG2 cells with chemical inducers of cytochrome P450 monooxygenase 3-methylcholanthrene and phenobarbital resulted in a further decrease of cell viability associated with DZN exposure. In addition, the metabolite diazoxon was more toxic than DZN. Our results also revealed that THC alleviated DZN-induced cytotoxicity and reactive oxygen and nitrogen species (RONS) generation in HepG2 cells. In conclusion, our data provide novel insights into the involvement of biotransformation in the mechanisms of DZN-induced cytotoxicity and suggest that amelioration of RONS accumulation might be involved in the protective effect of THC on DZN-induced liver injury.
RESUMO
Imidacloprid (IMD) is a neonicotinoid insecticide used in large quantities worldwide in both veterinary and agronomic applications. Several studies have shown adverse effects of IMD on non-target organisms, with the liver being identified as the main affected organ. This study aimed to evaluate the effects of IMD on human hepatoblastoma (HepG2) cells. HepG2 were exposed to IMD (0.25-2.0 mM) for 24 and 48 h. IMD treatment resulted in cytotoxicity in the HepG2, inhibiting cell proliferation in a dose- and time-dependent manner, starting at concentrations of 0.5 mM (24 h) and 0.25 mM (48 h), and reducing cell viability from 0.5 mM onwards (24 and 48 h). IMD significantly decreased the mitochondrial membrane potential at both time points investigated (2.0 mM), and also induced damage to the cell membrane, demonstrated by significant dose and time-dependent increases in lactate dehydrogenase (LDH) release from concentrations of 1.0 mM (24 h) and 0.5 mM (48 h) upwards. IMD treatment also increased the production of reactive oxygen and nitrogen species (ROS/RNS) at rates above 50% following 0.5 mM (24 h) or 0.25 mM (48 h) concentrations, and caused a significant decrease in reduced/oxidized glutathione ratio (GSH/GSSG), indicating oxidative stress. Furthermore, the antioxidant dithiothreitol, which reacts with ROS/RNS and acts as a thiol reducing agent, inhibited the cytotoxic effect of IMD. In addition, the metabolite IMD-olefin was more toxic than IMD. Our results indicate that IMD induces cytotoxicity in HepG2 cells and that this effect may be associated with an increase in the generation of ROS/RNS.
Assuntos
Oxigênio , Espécies Reativas de Nitrogênio , Sobrevivência Celular , Glutationa/metabolismo , Células Hep G2 , Humanos , Neonicotinoides/toxicidade , Nitrocompostos , Nitrogênio , Estresse Oxidativo , Espécies Reativas de Nitrogênio/farmacologia , Espécies Reativas de Oxigênio/metabolismoRESUMO
There is no use restriction associated with bees for many fungicides used in agriculture; however, this does not always mean that these pesticides are harmless for these nontarget organisms. We investigated whether the fungicide pyraclostrobin, which acts on fungal mitochondria, also negatively affects honey bee mitochondrial bioenergetics. Honey bees were collected from 5 hives and anesthetized at 4 °C. The thoraces were separated, and mitochondria were isolated by grinding, filtering, and differential centrifugation. An aliquot of 0.5 mg of mitochondrial proteins was added to 0.5 mL of a standard reaction medium with 4 mM succinate (complex II substrate) plus 50 nM rotenone (complex I inhibitor), and mitochondrial respiration was measured at 30 °C using a Clark-type oxygen electrode. Mitochondrial membrane potential was determined spectrofluorimetrically using safranin O as a probe, and adenosine triphosphate (ATP) synthesis was determined by chemiluminescence. Pyraclostrobin at 0 to 50 µM was tested on the mitochondrial preparations, with 3 repetitions. Pyraclostrobin inhibited mitochondrial respiration in a dose-dependent manner at concentrations of 10 µM and above, demonstrating typical inhibition of oxidative phosphorylation. Pyraclostrobin also promoted a decline in the mitochondrial membrane potential at doses of 5 µM and above and in ATP synthesis at 15 µM and above. We conclude that pyraclostrobin interferes with honey bee mitochondrial function, which is especially critical for the energy-demanding flight activity of foraging bees. Environ Toxicol Chem 2020;39:1267-1272. © 2020 SETAC.
Assuntos
Abelhas/efeitos dos fármacos , Fungos/efeitos dos fármacos , Fungicidas Industriais/toxicidade , Mitocôndrias/efeitos dos fármacos , Estrobilurinas/toxicidade , Trifosfato de Adenosina/metabolismo , Animais , Metabolismo Energético/efeitos dos fármacos , Fungos/metabolismo , Fungicidas Industriais/metabolismo , Inativação Metabólica/efeitos dos fármacos , Potencial da Membrana Mitocondrial , Mitocôndrias/metabolismo , Estrobilurinas/metabolismoRESUMO
ABSTRACT Introduction: Intense physical exercise affects the balance between the production of reactive oxygen species and antioxidant defense in the muscle. Carnosine is a cytoplasmic dipeptide composed of the amino acids β-alanine and histidine. Objective: This study aimed to evaluate the effect of carnosine and its precursor β-alanine on oxidative damage caused by intense physical exercise in the soleus muscle of rats. Methods: Male Wistar rats weighing between 200 and 240 g were divided into four groups: control, exercise, exercise + β-alanine and exercise + carnosine. The animals from the groups that underwent the exercise ran on a treadmill for 60 minutes at 25 m/minute. Factors related to muscle damage and oxidative stress were assessed in soleus muscle homogenate and blood serum. Results: The exercise promoted muscle damage, as observed through increased serum activity of enzymes aspartate aminotransferase and creatine kinase. It also induced oxidative stress in soleus muscle, as seen by the increased activity of the enzymes glutathione peroxidase and glutathione reductase, decreased concentration of reduced glutathione, and increased concentration of malondialdehyde, an indicator of lipid peroxidation. Carnosine kept the creatine kinase, glutathione peroxidase and glutathione reductase enzyme activity values, and the concentration of reduced glutathione and malondialdehyde, close to those of the control group. Conclusion: The results indicate that pretreatment with carnosine protected the rat soleus muscle against oxidative damage and consequent injury caused by intense physical exercise. Level of evidence II; Therapeutic studies-Investigating the treatment results.
RESUMO Introdução: O exercício físico intenso afeta o equilíbrio entre a produção de espécies reativas de oxigênio e a defesa antioxidante no músculo. A carnosina é um dipeptídeo citoplasmático composto pelos aminoácidos β-alanina e histidina. Objetivo: O presente trabalho teve como objetivo avaliar o efeito da carnosina e do seu precursor β-alanina nos danos oxidativos causados pelo exercício físico intenso no músculo sóleo de ratos. Métodos: Ratos Wistar machos pesando entre 200 e 240 g foram divididos em quatro grupos: controle, exercício, exercício + β-alanina e exercício + carnosina. Os animais dos grupos submetidos ao exercício correram em esteira por 60 minutos a 25 m/minuto. Fatores relacionados ao dano muscular e estresse oxidativo foram avaliados no soro sanguíneo e no homogenato do músculo sóleo. Resultados: O exercício promoveu lesão muscular conforme observado através do aumento da atividade sérica das enzimas aspartato aminotransferase e creatina quinase. Além disso, induziu o estresse oxidativo no músculo sóleo, observado pelo aumento da atividade das enzimas glutationa peroxidase e glutationa redutase, diminuição da concentração de glutationa reduzida e aumento na concentração de malondialdeído, um indicador de lipoperoxidação. A carnosina manteve os valores da atividade das enzimas creatina quinase, glutationa peroxidase e glutationa redutase, além da concentração de glutationa reduzida e malondialdeído próximos aos do grupo controle. Conclusão: Os resultados indicam que o tratamento prévio com carnosina protegeu o músculo sóleo de ratos contra os danos oxidativos e a consequente lesão provocada pelo exercício físico intenso. Nível de evidência II; Estudos terapêuticos-investigação dos resultados do tratamento.
RESUMEN Introducción: El ejercicio físico intenso afecta al equilibrio entre la producción de especies reactivas de oxígeno y la defensa antioxidante en el músculo. La carnosina es un dipéptido citoplasmático compuesto por los aminoácidos β-alanina e histidina. Objetivo: El presente trabajo tuvo como objetivo evaluar el efecto de la carnosina y de su precursor β-alanina en los daños oxidativos causados por el ejercicio físico intenso en el músculo sóleo de ratones. Métodos: Ratones Wistar machos pesando entre 200 y 240 g fueron divididos en cuatro grupos: control, ejercicio, ejercicio + β-alanina y ejercicio + carnosina. Los animales de los grupos sometidos al ejercicio corrieron en cinta durante 60 minutos a 25 m/minuto. Se evaluaron los factores relacionados al daño muscular y al estrés oxidativo en el suero sanguíneo y el homogenato del músculo sóleo. Resultados: El ejercicio promovió lesión muscular, conforme fuera observado a través del aumento de la actividad sérica de las enzimas aspartato aminotransferasa y creatina quinasa. Además, indujo al estrés oxidativo en el músculo sóleo, observado por el aumento de la actividad de las enzimas glutatión peroxidasa y glutatión reductasa, disminución de la concentración de glutatión reducido y aumento de la concentración de malondialdehído, un indicador de lipoperoxidación. La carnosina mantuvo los valores de actividad de las enzimas creatina quinasa, glutatión peroxidasa y glutatión reductasa, además de la concentración de glutatión reducido y malondialdehído cercanos a los del grupo de control. Conclusión: Los resultados indican que el tratamiento previo con carnosina protegió al músculo sóleo de ratones contra los daños oxidativos y la consiguiente lesión causada por el ejercicio físico intenso. Nivel de evidencia II; Estudios terapéuticos-Investigación de los resultados del tratamiento.
RESUMO
ABSTRACT The aim of this study was to characterize the mechanism of toxicity of fipronil on hepatocytes isolated from the rat and the effect of its biotransformation on the toxicological potential. The toxicity of fipronil was assessed by monitoring the oxygen consumption and mitochondrial membrane potential, intracellular ATP concentration, Ca2+ homeostasis and cell viability. The cell viability was evaluated by trypan blue exclusion in hepatocytes that were isolated from the normal rats and by the release of the enzymes alanine transaminase and aspartate transaminase in hepatocytes that were isolated from the normal rats or proadifen-pretreated rats. Fipronil reduced mitochondrial respiration in the cells that were energized with glutamate plus malate in a dose-dependent manner and dissipated the mitochondrial membrane potential that was accompanied by a reduction in ATP concentration and a disruption of intracellular Ca2+ homeostasis. The cell viability was affected by fipronil with higher potency in hepatocytes that were isolated from the normal rats, which indicated that the metabolism of this insecticide increased its toxicological potential. The results of this study indicated that the toxicity of fipronil to the hepatocytes was related to the inhibition of mitochondrial activity, which led to decreased ATP synthesis and a consequent alteration in intracellular Ca2+ homeostasis and ultimately resulted in cell death.
RESUMO
INTRODUÇÃO: os músculoesqueléticos são tecidos dinâmicos que podem alterar suas características fenotípicas proporcionando melhor adaptação funcional com estímulos variados. A L-tiroxina é um hormônio produzido pela glândula tireoide e tem sido utilizada como modelo experimental para estimulação de estresse oxidativo no músculo esquelético. A coenzima Q10 é uma provitamina lipossolúvel sintetizada endogenamente e naturalmente encontrada em alimentos como carne vermelha, peixes, cereais, brócolis e espinafre. Apresenta propriedade antioxidante e tem potencial no tratamento de doenças degenerativas e neuromusculares. OBJETIVO: avaliar o efeito protetor da coenzima Q10 no músculo sóleo de ratos frente aos danos oxidativos provocados pela L-tiroxina. MÉTODOS: os ratos foram distribuídos em quatro grupos de seis animais cada: Grupo 1 controle; Grupo 2 coenzima Q10; Grupo 3 L-tiroxina e Grupo 4 coenzima Q10 e L-tiroxina. Após a eutanásia, o sangue dos animais foi colhido e foi analisada a atividade sérica das enzimas creatina quinase CK e aspartato aminotransferase AST. No homogenato do músculo sóleo foram avaliados fatores relacionados ao estresse oxidativo. RESULTADOS: a coenzima Q10 protegeu o músculo sóleo dos danos provocados pela L-tiroxina e favoreceu a manutenção da atividade das enzimas antioxidantes glutationa redutase e glutationa peroxidase, da concentração de glutationa reduzida e oxidada, além de evitar a lipoperoxidação. CONCLUSÃO: os resultados indicam que a coenzima Q10 protege o músculo sóleo de ratos dos danos oxidativos provocados pela L-tiroxina. .
INTRODUCTION: skeletal muscles are dynamic tissue that can change their phenotypic characteristics providing a better functional adaptation to different stimuli. L-thyroxine is a hormone produced by the thyroid gland and has been used as an experimental model for stimulation of oxidative stress in skeletal muscle. Coenzyme Q10 CoQ10 is a fat-soluble provitamin endogenously synthesized and found naturally in foods such red meat, fish, cereals, broccoli and spinach. It has antioxidant properties and potential in the treatment of degenerative and neuromuscular diseases. OBJECTIVE: to evaluate the protective effect of CoQ10 in the soleus muscle of rats against the oxidative damage caused by L-thyroxine. METHODS: the rats were divided in four groups of six animals each: Group 1 control; Group 2 coenzyme Q10; Group 3 L-thyroxine, and Group 4 coenzyme Q10 and L-thyroxine. After euthanasia, blood was collected and serum activity of the enzymes creatine kinase CK and aspartate aminotransferase AST was analyzed. In the soleus muscle homogenates the factors related to oxidative stress were assessed. RESULTS: CoQ10 protected the soleus muscle against the damage caused by L-thyroxine and favored the maintenance of the antioxidant enzymes glutathione reductase and glutathione peroxidase, the concentration of decreased and oxidized glutathione, and prevented lipid peroxidation. CONCLUSION: the results indicate that CoQ10 protects rat soleus muscle from oxidative damage caused by L-thyroxine. .
INTRODUCCIÓN: los músculos esqueléticos son tejidos dinámicos que pueden alterar sus características fenotípicas proporcionando mejor adaptación funcional con estímulos variados. La L-tiroxina es una hormona producida por la glándula tiroides y ha sido utilizada como modelo experimental para estimulación de estrés oxidativo en el músculo esquelético. La coenzima Q10 es una provitamina liposoluble sintetizada endogénicamente y naturalmente encontrada en alimentos como carne roja, pescados, cereales, brócolis y espinaca. Presenta propiedad antioxidante y tiene potencial en el tratamiento de enfermedades degenerativas y neuromusculares. OBJETIVO: evaluar el efecto protector de la coenzima Q10 en el músculo soleo de ratas frente a los daños oxidativos provocados por la L-tiroxina. MÉTODOS: Las ratas fueron distribuidas en cuatro grupos de seis animales cada uno: Grupo 1 control; Grupo 2 coenzima Q10; Grupo 3 L-tiroxina y Grupo 4 coenzima Q10 y L-tiroxina. Después de la eutanasia, la sangre de los animales fue recogida y fue analizada la actividad sérica de las enzimas creatina quinasa CK y aspartato aminotransferasa AST. En el homogenato del músculo soleo fueron evaluados factores relacionados al estrés oxidativo. RESULTADOS: la coenzima Q10 protegió al músculo soleo de los daños provocados por la L-tiroxina y favoreció el mantenimiento de la actividad de las enzimas antioxidantes glutationa reductasa y glutationa peroxidasa, de la concentración de glutationa reducida y oxidada, además de evitar la lipoperoxidación. CONCLUSIÓN: los resultados indican que la coenzima Q10 protege al músculo soleo de ratas de los daños oxidativos provocados por la L-tiroxina .
RESUMO
O fígado desempenha uma função central no metabolismo devido à sua interposição entre o trato digestivo e a circulação geral do organismo. Ele é também o principal órgão envolvido na biotransformação de substâncias exógenas (xenobióticos), com capacidade de converter compostos hidrofóbicos em hidrossolúveis, mais facilmente eliminados pelo organismo. O gossipol é uma substância fenólica tóxica presente na semente de algodão (Gossypium sp). Com o objetivo de estudar os mecanismos envolvidos na hepatotoxicidade do gossipol avaliou-se os seus efeitos no sistema antioxidante do fígado de ratos no que diz respeito ao estresse oxidativo e aspectos histopatológicos. Foram utilizados ratos machos da linhagem Wistar, separados em dois grupos, sendo que um recebeu óleo de canola (veículo, grupo Controle) e o outro recebeu gossipol na dosagem de 40 mg/kg de peso vivo do animal por 15 dias (grupo Tratado). O tratamento com gossipol promoveu alterações na atividade sérica das enzimas marcadoras de dano hepático e um significativo estresse oxidativo caracterizado pela diminuição nos níveis da glutationa reduzida (GSH) e consequente aumento da glutationa oxidada (GSSG), incluindo, ainda, danos à membrana plasmática e de organelas demonstrados pela peroxidação lipídica. O resultado da avaliação histopatológica demonstrou degeneração dos hepatócitos.
The liver plays a central role in metabolism due to its interposition between the digestive tract and the general circulation of the organism. It is also the main organ involved in biotransformation of exogenous substances (xenobiotics), with ability to convert hydrophobic compounds in water-soluble, more easily eliminated by the body. Gossypol is a toxic phenolic substance present in cotton seed (Gossypium sp.). Aiming to study the mechanisms involved in the hepatotoxicity of gossypol we evaluate its effects on the antioxidant system of rat liver performing an experiment that investigated the oxidative stress and the histopathological alterations. In this study, we used Wistar rats, divided into two groups, one that received canola oil (vehicle, Control group) and another that received gossypol at a dose of 40mg/kg body weight of the animal for 15 days (Treated group). The treatment with gossypol caused alterations in the activity of seric enzymes that indicate hepatic injury and a significant oxidative stress characterized by a decrease of reduced glutathione (GSH) levels and a consequent increase in oxidized glutathione (GSSG), including further damage to the plasma membrane and organelles showed by lipid peroxidation. The result of histopathological evaluation showed degeneration of the hepatocytes.
Assuntos
Animais , Camundongos , Fígado/fisiopatologia , Glutationa , Gossipol/administração & dosagem , Estresse Oxidativo , Ratos Wistar , Brassica napus/efeitos adversos , Gossipol/efeitos adversos , Gossipol/toxicidade , MetabolismoRESUMO
Monocrotaline (MCT) is a pyrrolizidine alkaloid present in plants of the genus Crotalaria that causes cytotoxicity and genotoxicity in animals and humans. It is well established that the toxicity of MCT results from its hepatic bioactivation to dehydromonocrotaline (DHM), an alkylating agent, but the exact mechanism of action remains unknown. In a previous study, we demonstrated DHM's inhibition of mitochondrial NADH-dehydrogenase activity at micromolar concentrations, which is an effect associated with a significant reduction in ATP synthesis. As a follow-up study, we have evaluated the ability of DHM to induce mitochondrial permeability transition (MPT) and its associated processes in isolated rat liver mitochondria. In the presence of 10 microM Ca(2+), DHM (50-250 microM) elicited MPT in a concentration-dependent, but cyclosporine A-independent manner, as assessed by mitochondrial swelling, which is associated with mitochondrial Ca(2+) efflux and cytochrome c release. DHM (50-250 microM) did not cause hydrogen peroxide accumulation but did deplete endogenous glutathione and NAD(P)H, while oxidizing protein thiol groups. These results potentially indicate the involvement of mitochondria, via apoptosis, in the well-documented cytotoxicity of monocrotaline.
Assuntos
Alquilantes/farmacologia , Ciclosporina/farmacologia , Citocromos c/metabolismo , Imunossupressores/farmacologia , Mitocôndrias/efeitos dos fármacos , Mitocôndrias/enzimologia , Monocrotalina/análogos & derivados , Animais , Apoptose/efeitos dos fármacos , Cálcio/metabolismo , Glutationa/metabolismo , Peróxido de Hidrogênio/metabolismo , Técnicas In Vitro , Peroxidação de Lipídeos/efeitos dos fármacos , Masculino , Proteínas de Transporte da Membrana Mitocondrial/genética , Proteínas de Transporte da Membrana Mitocondrial/metabolismo , Dilatação Mitocondrial/efeitos dos fármacos , Monocrotalina/farmacologia , NADP/metabolismo , Permeabilidade/efeitos dos fármacos , Ratos , Ratos Wistar , Compostos de Sulfidrila/metabolismoRESUMO
Monocrotaline (MCT) is a pyrrolizidine alkaloid present in the plants of the Crotalaria species that causes cytotoxicity and genotoxicity in animals and humans, and it is hepatically metabolized to the alkylating agent dehydromonocrotaline by cytochrome P-450. The exact cellular and molecular mechanisms of MCT-induced tissue injury remain unclear. We previously demonstrated that dehydromonocrotaline, but not monocrotaline, inhibits the activity of NADH-dehydrogenase at micromolar concentrations in isolated liver mitochondria, an effect associated with significantly reduced ATP synthesis. Impairment of energy metabolism is expected to lead to several alterations in cell metabolism. In this work, the action of different concentrations of monocrotaline (250, 500, and 750microM) on energy metabolism-linked parameters was investigated in isolated perfused rat livers. In the fed state, monocrotaline increased glycogenolysis and glycolysis, whereas in the livers of fasted rats, it decreased gluconeogenesis and urea synthesis from l-alanine. These metabolic alterations were only found in livers of phenobarbital-treated rats, indicating that active metabolites including dehydromonocrotaline were responsible for the observed activity. Our findings indicate that hepatic metabolic changes may be implicated, partly at least, in the hepatotoxicity of monocrotaline in animals and humans.