Influência do extrato do chá verde (Camellia sinensis) no metabolismo energético cardíaco de ratos expostos a doxorrubicina
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Data
2019-02-26
Autores
Modesto, Pamela Nayara
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Universidade Estadual Paulista (Unesp)
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INTRODUÇÃO: A doxorrubicina (DOX) é um medicamento muito eficaz no tratamento de vários tipos de câncer, mas seu uso em larga escala tem causado preocupação devido à cardiotoxicidade causada pela droga. Não se sabe exatamente quais mecanismos estão envolvidos, mas acredita-se nos papeis centrais da ligação da DOX com a topoisomerase 2-β (Top2-β), que é uma enzima que protege a célula da citotoxicidade e destruição; da interação DOX-ferro gerando espécies reativas de oxigênio; além de disfunção mitocondrial, seguida por muitas outras vias secundárias ativadas por essas primárias, como inflamação e fatores da matriz extracelular (MEC). Por outro lado, o chá verde, uma bebida muito popular em todo o mundo, tem efeitos antioxidantes e antitumorais. MÉTODOS: Foram utilizados 60 ratos Wistar machos. Estes animais foram divididos grupos: C=20 (controle) que recebeu ração padrão e administração intraperitoneal de salina, CV=20 (controle + chá verde) que receberam ração adicionada de extrato de chá verde e administração intraperitoneal de solução salina, D=20 (doxorrubicina) que recebeu ração padrão e administração intraperitoneal de doxorrubicina e DCV=20 (doxorrubicina + chá verde) que receberam ração adicionada de extrato de chá verde e administração intraperitoneal de doxorrubicina. A ração foi oferecida por 35 dias e no 33º dia a infusão de doxorrubicina ou soro fisiológico foi realizada na mesma proporção (20 mg / kg em dose única) e os animais foram eutanasiados 48 horas após a injeção do fármaco. Os ratos foram submetidos ao ecocardiograma para avaliação da morfologia e função cardíacas e foram realizadas análises de atividade enzimática, expressão de proteínas, relacionadas à proteção celular, estresse oxidativo,metabolismo energético, inflamação e MEC. RESULTADOS: O estudo ecocardiográfico mostrou que a DOX aumentou o átrio esquerdo, a espessura relativa da parede e reduziu a FC que foram atenuados pelo chá verde. No grupo D houve aumento do estresse oxidativo caracterizado pela maior formação de hidroperóxido de lipídios (HP) e redução da glutationa peroxidase (GPx), que foram atenuados no grupo DCV. Em relação ao metabolismo energético, houve aumento de enzimas da via glicolítica anaeróbia (fosfofrutoquinase e lactato desidrogenase), diminuição de enzima da oxidação de ácidos graxos (3- hidroxiacil coenzima A desidrogenase), redução da atividade de enzimas do ciclo do citrato (citrato sintase), complexos mitocondriais (complexo I e II) e ATP sintase, no grupo D. O grupo DCV restabeleceu o padrão de uso da via glicolítica e oxidação de ácidos graxos. Embora a DOX tenha reduzido a fosforilação da proteína quinase B em relação a sua expressão total (p-AKT/t-AKT, o chá verde não participou dessa via. Houve diminuição da expressão da Top2-β no grupo D, sendo que o chá verde aumentou a expressão dessa enzima, tanto no grupo DCV quanto no grupo CV. A inflamação foi maior no grupo D, evidenciada por maior expressão de TNF-α, CD45 e metaloprotease 2 de atividade intermediaria (MMP-2int), porém o chá verde não influenciou esses achados. Não houve alteração na expressão do colágeno I e III ou na presença de fibrose. CONCLUSÃO: A administração aguda de doxorrubicina causou remodelação cardíaca, sugerindo a presença de remodelamento concêntrico, disfunção diastólica e sistólica, atenuados pelo chá verde. Observou-se diminuição do Top2-β, aumento do estresse oxidativo e da inflamação e desbalanço do metabolismo energético, induzidos pela DOX. O chá verde aumentou a Top2-β, reduziu o estresse oxidativo e recuperou o metabolismo energético para valores próximos ao grupo controle. Portanto, este modelo experimental identificou potenciais mecanismos cardiotoxicidade induzida pela DOX e sugere os potenciais benefícios do chá verde, por provável ação em reduzir a citotoxicidade, a destruição celular e o estresse oxidativo, além de melhorar o metabolismo energético.
INTRODUCTION: doxorubicin (dox) is a very effective drug in the treatment of several types of cancer, but it plays an important role in cardiotoxicity. The mechanisms of DOX-induced cardiotoxicity include: binding to Top2-β, an enzyme that protects cells from citotoxicity and destruction; interaction with iron and altering intracellular and mitochondrial antioxidants enzymes activities, followed by many other secondary pathways activated by these primary, for example inflammation, estracellular matrix ( ECM) factors and others. On the other hand, green tea, a very popular beverage all over the world, has antioxidants and antitumor properties. METHODS: Sixty male Wistar rats were used. These animals were divided into groups: C = 20 (control) that received standard chow and intraperitoneal administration of saline, GT = 20 (control + green tea) receiving added chow of green tea extract and intraperitoneal administration of saline solution, D = 20 (doxorubicin) who received standard chow and intraperitoneal administration of doxorubicin and DGT = 20 (doxorubicin + green tea) who received added ration of green tea extract and intraperitoneal administration of doxorubicin. The feed was offered for 35 days and on the 33rd day the infusion of doxorubicin or saline was performed in the same proportion (20 mg / kg in a single dose) and the animals were euthanized 48 hours after the injection of the drug. The rats were submitted to echocardiogram to evaluate the cardiac morphology and function. Analyzes of enzymatic activity, protein expression, related to cell protection, oxidative stress, energy metabolism, inflammation and ECM were performed. RESULTS: DOX increased left atrium and relative wall thickness, aside of reducing heart rate, all of them were attenuated by green tea. In D group it was observed greater oxidative stress marked by lipid hydroperoxide (HP) and reduction of glutathione peroxidase (GPx), which was attenuated in the DGT group. In relation to energy metabolism, it was evidenced higher activity of anaerobic glycolytic pathway (phosphofructokinase and lactate dehydrogenase) enzymes, reduction in the activity of fatty acid oxidation (3-hydroxyacyl coenzyme a dehydrogenase), reduction of the enzymatic activity of the citrate cycle (citrate synthase), mitochondrial complexes (complex I and II) and ATP synthase in group D. The DGT group recovery the pattern of glycolytic fatty acids oxidation pathways. Although DOX reduced the protein kinase phosphorylation with respect to the total expression (p-akt / t-akt), green tea did not influenced this. There was a decrease in the expression of Top2-β in group D, and green tea increased expression of this enzyme, both in the DGT group and in the GT group. The inflammation was higher in group D, evidenced by greater expression of TNF-α, CD45 and metalloprotease 2 of intermediate activity (MMP-2int), but green tea did not influence these findings. There was no change in the expression of collagen I and III or in the presence of fibrosis. CONCLUSION: the acute administration of doxorubicin caused cardiac remodeling, suggesting the presence of concentric remodeling, diastolic and systolic dysfunction, attenuated by green tea. It was observed a decrease of the Top2-β, increase of the oxidative stress and the inflammation and imbalance of the energetic metabolism, induced by DOX. Green tea increased Top2-β, reduced oxidative stress, and recovered energy metabolism to values close to the control group. Therefore, this experimental model identified potential mechanisms of DOX-induced cardiotoxicity and suggests the potential benefits of green tea for its likely action in reducing cytotoxicity, cell destruction and oxidative stress, as well as improving energy metabolism.
INTRODUCTION: doxorubicin (dox) is a very effective drug in the treatment of several types of cancer, but it plays an important role in cardiotoxicity. The mechanisms of DOX-induced cardiotoxicity include: binding to Top2-β, an enzyme that protects cells from citotoxicity and destruction; interaction with iron and altering intracellular and mitochondrial antioxidants enzymes activities, followed by many other secondary pathways activated by these primary, for example inflammation, estracellular matrix ( ECM) factors and others. On the other hand, green tea, a very popular beverage all over the world, has antioxidants and antitumor properties. METHODS: Sixty male Wistar rats were used. These animals were divided into groups: C = 20 (control) that received standard chow and intraperitoneal administration of saline, GT = 20 (control + green tea) receiving added chow of green tea extract and intraperitoneal administration of saline solution, D = 20 (doxorubicin) who received standard chow and intraperitoneal administration of doxorubicin and DGT = 20 (doxorubicin + green tea) who received added ration of green tea extract and intraperitoneal administration of doxorubicin. The feed was offered for 35 days and on the 33rd day the infusion of doxorubicin or saline was performed in the same proportion (20 mg / kg in a single dose) and the animals were euthanized 48 hours after the injection of the drug. The rats were submitted to echocardiogram to evaluate the cardiac morphology and function. Analyzes of enzymatic activity, protein expression, related to cell protection, oxidative stress, energy metabolism, inflammation and ECM were performed. RESULTS: DOX increased left atrium and relative wall thickness, aside of reducing heart rate, all of them were attenuated by green tea. In D group it was observed greater oxidative stress marked by lipid hydroperoxide (HP) and reduction of glutathione peroxidase (GPx), which was attenuated in the DGT group. In relation to energy metabolism, it was evidenced higher activity of anaerobic glycolytic pathway (phosphofructokinase and lactate dehydrogenase) enzymes, reduction in the activity of fatty acid oxidation (3-hydroxyacyl coenzyme a dehydrogenase), reduction of the enzymatic activity of the citrate cycle (citrate synthase), mitochondrial complexes (complex I and II) and ATP synthase in group D. The DGT group recovery the pattern of glycolytic fatty acids oxidation pathways. Although DOX reduced the protein kinase phosphorylation with respect to the total expression (p-akt / t-akt), green tea did not influenced this. There was a decrease in the expression of Top2-β in group D, and green tea increased expression of this enzyme, both in the DGT group and in the GT group. The inflammation was higher in group D, evidenced by greater expression of TNF-α, CD45 and metalloprotease 2 of intermediate activity (MMP-2int), but green tea did not influence these findings. There was no change in the expression of collagen I and III or in the presence of fibrosis. CONCLUSION: the acute administration of doxorubicin caused cardiac remodeling, suggesting the presence of concentric remodeling, diastolic and systolic dysfunction, attenuated by green tea. It was observed a decrease of the Top2-β, increase of the oxidative stress and the inflammation and imbalance of the energetic metabolism, induced by DOX. Green tea increased Top2-β, reduced oxidative stress, and recovered energy metabolism to values close to the control group. Therefore, this experimental model identified potential mechanisms of DOX-induced cardiotoxicity and suggests the potential benefits of green tea for its likely action in reducing cytotoxicity, cell destruction and oxidative stress, as well as improving energy metabolism.
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Extrato de chá verde, Doxorrubicina, Cardiotoxicidade, Estresse oxidativo, Metabolismo energético, Green tea extract, Doxorrubicin, Cardiotoxicity, Oxidative stress, Energy metabolismo