Mechanisms involved in reproductive damage caused by gossypol in rats and protective effects of vitamin E.

BACKGROUND: Gossypol is a chemical present in the seeds of cotton plants (Gossypium sp.) that reduces fertility in farm animals. Vitamin E is an antioxidant and may help to protect cells and tissues against the deleterious effects of free radicals. The aim of this study was to evaluate the mechanisms of reproductive toxicity of gossypol in rats and the protective effects of vitamin E. Forty Wistar rats were used, divided into four experimental groups (n = 10): DMSO/saline + corn oil; DMSO/saline + vitamin E; gossypol + corn oil; and gossypol + vitamin E. RESULTS: Fertility was significantly reduced in male rats treated with gossypol in that a significant decrease in epididymal sperm count was observed (P < 0.05) and the number of offspring was significantly reduced in females mated with them (P < 0.05). This dysfunction was prevented by vitamin E. Gossypol caused a significant increase in the activity of the enzymes glutathione peroxidase (P < 0.01) and glutathione reductase (P < 0.01), but vitamin E did not reduce the enzyme activities (P > 0.05). The levels of reduced glutathione and pyridine nucleotides in testis homogenate were significantly reduced by gossypol (P < 0.05 and P < 0.01, respectively) and this reduction was accompanied by increased levels of oxidized glutathione (P < 0.05). Vitamin E showed a preventive effect on the changes in the levels of these substances. Gossypol significantly increased the levels of malondialdehyde (P < 0.01), a lipid peroxidation indicator, whereas treatment with vitamin E inhibited the action of the gossypol. Vitamin E prevented a decrease in mitochondrial ATP induced by gossypol (P < 0.05). CONCLUSIONS: This study suggests that the reproductive dysfunction caused by gossypol may be related to oxidative stress and mitochondrial bioenergetic damage and that treatment with vitamin E can prevent the infertility caused by the toxin.

Protective effect of bixin on carbon tetrachloride-induced hepatotoxicity in rats.

BACKGROUND: The liver is an important organ for its ability to transform xenobiotics, making the liver tissue a prime target for toxic substances. The carotenoid bixin present in annatto is an antioxidant that can protect cells and tissues against the deleterious effects of free radicals. In this study, we evaluated the protective effect of bixin on liver damage induced by carbon tetrachloride (CCl4) in rats. RESULTS: The animals were divided into four groups with six rats in each group. CCl4 (0.125 mL kg(-1) body wt.) was injected intraperitoneally, and bixin (5.0 mg kg(-1) body wt.) was given by gavage 7 days before the CCl4 injection. Bixin prevented the liver damage caused by CCl4, as noted by the significant decrease in serum aminotransferases release. Bixin protected the liver against the oxidizing effects of CCl4 by preventing a decrease in glutathione reductase activity and the levels of reduced glutathione and NADPH. The peroxidation of membrane lipids and histopathological damage of the liver was significantly prevented by bixin treatment. CONCLUSION: Therefore, we can conclude that the protective effect of bixin against hepatotoxicity induced by CCl4 is related to the antioxidant activity of the compound.

Comparative effects of fipronil and its metabolites sulfone and desulfinyl on the isolated rat liver mitochondria.

Fipronil is an insecticide extensively used to control pests in crops and animals. There are relates of poisoning due to exposure of fipronil in mammals and the liver has been suggested as potential target. In this study, we evaluated the effects of fipronil and its metabolites sulfone and desulfinyl on the bioenergetics, reactive oxygen species (ROS) production and calcium efflux from mitochondria isolated from rat liver. Fipronil (5-25 µM) inhibited state-3 respiration in mitochondria energized with glutamate plus malate, substrates of complex I of the respiratory chain and decreased the mitochondrial membrane potential resulting in inhibition of ATP synthesis. Fipronil also caused uncoupling in succinate-energized mitochondria and calcium efflux. The metabolites sulfone and desulfinyl also acted as mitochondrial inhibitors and uncouplers and caused calcium efflux, but with different potencies, being the sulfone the more potent one. These effects of fipronil and its metabolites on mitochondrial bioenergetics and calcium homeostasis may be related to toxic effects of the insecticide in the liver.

Carnosine avoids the oxidative damage caused by intense exercise on rat soleus muscle / Carnosina evita o dano oxidativo causado pelo exercício intenso no músculo sóleo de ratos / Carnosina evita el daño oxidativo causado por el ejercicio intenso en el músculo sóleo de ratones

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.

Fipronil and imidacloprid reduce honeybee mitochondrial activity.

Bees have a crucial role in pollination; therefore, it is important to determine the causes of their recent decline. Fipronil and imidacloprid are insecticides used worldwide to eliminate or control insect pests. Because they are broad-spectrum insecticides, they can also affect honeybees. Many researchers have studied the lethal and sublethal effects of these and other insecticides on honeybees, and some of these studies have demonstrated a correlation between the insecticides and colony collapse disorder in bees. The authors investigated the effects of fipronil and imidacloprid on the bioenergetic functioning of mitochondria isolated from the heads and thoraces of Africanized honeybees. Fipronil caused dose-dependent inhibition of adenosine 5'-diphosphate-stimulated (state 3) respiration in mitochondria energized by either pyruvate or succinate, albeit with different potentials, in thoracic mitochondria; inhibition was strongest when respiring with complex I substrate. Fipronil affected adenosine 5'-triphosphate (ATP) production in a dose-dependent manner in both tissues and substrates, though with different sensitivities. Imidacloprid also affected state-3 respiration in both the thorax and head, being more potent in head pyruvate-energized mitochondria; it also inhibited ATP production. Fipronil and imidacloprid had no effect on mitochondrial state-4 respiration. The authors concluded that fipronil and imidacloprid are inhibitors of mitochondrial bioenergetics, resulting in depleted ATP. This action can explain the toxicity of these compounds to honeybees.

The role of mitochondria and biotransformation in abamectin-induced cytotoxicity in isolated rat hepatocytes.

Abamectin (ABA), which belongs to the family of avermectins, is used as a parasiticide; however, ABA poisoning can impair liver function. In a previous study using isolated rat liver mitochondria, we observed that ABA inhibited the activity of adenine nucleotide translocator and FoF1-ATPase. The aim of this study was to characterize the mechanism of ABA toxicity in isolated rat hepatocytes and to evaluate whether this effect is dependent on its metabolism. The toxicity of ABA was assessed by monitoring oxygen consumption and mitochondrial membrane potential, intracellular ATP concentration, cell viability, intracellular Ca(2+) homeostasis, release of cytochrome c, caspase 3 activity and necrotic cell death. ABA reduces cellular respiration in cells energized with glutamate and malate or succinate. The hepatocytes that were previously incubated with proadifen, a cytochrome P450 inhibitor, are more sensitive to the compound as observed by a rapid decrease in the mitochondrial membrane potential accompanied by reductions in ATP concentration and cell viability and a disruption of intracellular Ca(2+) homeostasis followed by necrosis. Our results indicate that ABA biotransformation reduces its toxicity, and its toxic action is related to the inhibition of mitochondrial activity, which leads to decreased synthesis of ATP followed by cell death.

Mechanism for the uncoupling of oxidative phosphorylation by juliprosopine on rat brain mitochondria.

Prosopis juliflora, popularly known as Algaroba, is a major problem because the lack of food during the driest times of the year and its high palatability and nutritional value make its fruits (pods) much appreciated by cattle, goats, sheep and other animals. However, the consumption of this plant for long periods can cause a disease called cara-torta (pie face), which is characterized by cranial nerve dysfunction, mainly due to the degeneration and disappearance of neurons in the trigeminal motor nucleus. Algaroba contains piperidine alkaloids that have been suggested as being responsible for its toxicity; one of these alkaloids is juliprosopine. This study was conducted to evaluate the mechanisms of action of juliprosopine in isolated rat brain mitochondria to evaluate the potential mechanisms that lead to neurotoxicity in animals intoxicated by algaroba. Juliprosopine stimulated state-4 respiration at concentrations of 10-25 µM, affected the membrane potential at all concentrations studied (5-25 µM) and affected ATP production only at higher concentrations (15 and 25 µM). Juliprosopine cannot be classified as a member of the protonophoric class of uncouplers, such as 2,4-dinitrophenol or CCCP (m-chlorophenylhydrazone), due to its inability to promote mitochondrial swelling in the hyposmotic medium of potassium acetate. In addition, carboxyatractyloside, Mg(2+), cyclosporine A and dithiothreitol did not protect the uncoupling induced by juliprosopine. Because juliprosopine increased the fluorescence responses of mitochondria labeled with 1-aniline-8-naphthalene sulfonate (ANS) and DPH (1,6-diphenyl-1,3,5-hexatriene), we suggested that its uncoupling action must be attributed to a modification of the arrangement of the inner mitochondrial membrane.

Citotoxicity of Fipronil on Hepatocytes Isolated from Rat and Effects of Its Biotransformation

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.

Efeito da coenzima Q10 nos danos oxidativos induzidos pela L-tiroxina no músculo sóleo de ratos / Effect of coenzyme Q10 in the L-thyroxine-induced oxidative damage on rat soleus muscle / Efecto de la coenzima Q10 en los daños oxidativos inducidos por la L-tiroxina en el músculo soleo de ratas

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 .

Mechanisms involved in reproductive damage caused by gossypol in rats and protective effects of vitamin E

BACKGROUND: Gossypol is a chemical present in the seeds of cotton plants (Gossypium sp.) that reduces fertility in farm animals. Vitamin E is an antioxidant and may help to protect cells and tissues against the deleterious effects of free radicals. The aim of this study was to evaluate the mechanisms of reproductive toxicity of gossypol in rats and the protective effects of vitamin E. Forty Wistar rats were used, divided into four experimental groups (n = 10): DMSO/ saline + corn oil; DMSO/saline + vitamin E; gossypol + corn oil; and gossypol + vitamin E. RESULTS: Fertility was significantly reduced in male rats treated with gossypol in that a significant decrease in epididy-mal sperm count was observed (P < 0.05) and the number of offspring was significantly reduced in females mated with them (P < 0.05). This dysfunction was prevented by vitamin E. Gossypol caused a significant increase in the activity of the enzymes glutathione peroxidase (P < 0.01) and glutathione reductase (P < 0.01), but vitamin E did not reduce the enzyme activities (P > 0.05). The levels of reduced glutathione and pyridine nucleotides in testis homogen-ate were significantly reduced by gossypol (P < 0.05 and P < 0.01, respectively) and this reduction was accompanied by increased levels of oxidized glutathione (P < 0.05). Vitamin E showed a preventive effect on the changes in the levels of these substances. Gossypol significantly increased the levels of malondialdehyde (P < 0.01), a lipid peroxida-tion indicator, whereas treatment with vitamin E inhibited the action of the gossypol. Vitamin E prevented a decrease in mitochondrial ATP induced by gossypol (P < 0.05). CONCLUSIONS: This study suggests that the reproductive dysfunction caused by gossypol may be related to oxidative stress and mitochondrial bioenergetic damage and that treatment with vitamin E can prevent the infertility caused by the toxin.

Protective effect of bixin on carbon tetrachloride-induced hepatotoxicity in rats

BACKGROUND: The liver is an important organ for its ability to transform xenobiotics, making the liver tissue a prime target for toxic substances. The carotenoid bixin present in annatto is an antioxidant that can protect cells and tissues against the deleterious effects of free radicals. In this study, we evaluated the protective effect of bixin on liver damage induced by carbon tetrachloride (CCl4) in rats. RESULTS: The animals were divided into four groups with six rats in each group. CCl4 (0.125 mL kg-1 body wt.) was injected intraperitoneally, and bixin (5.0 mg kg-1 body wt.) was given by gavage 7 days before the CCl4 injection. Bixin prevented the liver damage caused by CCl4, as noted by the significant decrease in serum aminotransferases release. Bixin protected the liver against the oxidizing effects of CCl4 by preventing a decrease in glutathione reductase activity and the levels of reduced glutathione and NADPH. The peroxidation of membrane lipids and histopathological damage of the liver was significantly prevented by bixin treatment. CONCLUSION: Therefore, we can conclude that the protective effect of bixin against hepatotoxicity induced by CCl4 is related to the antioxidant activity of the compound.