Efeitos do tratamento crônico de natação e da terapia estrogênica sobre a reatividade vascular coronariana e expressão das enzimas antioxidantes em ratas ovarectomizadas

• Autor(a) principal: Claudio, Erick Roberto Gonçalves
• Data de Publicação: 2012
• Tipo de documento: Dissertação
• Idioma: por
• Título da fonte: Repositório Institucional da Universidade Federal do Espírito Santo (riUfes)
• Texto Completo: http://repositorio.ufes.br/handle/10/7969
• topic: Ovariectomia; Exercício físico; Terapia estrogênica; Fisiologia; 612

Cardiovascular diseases are a major source of morbidity and mortality in most industrialized countries. In women in the postmenopausal period these diseases remain the leading cause of death. With the decreased production of estrogens we can observe the appearance and the rise of many factors which could increase the risk of its development. Among these factors, the oxidative stress has been highlighted as an important mediator with significant contribution in the pathophysiology of many diseases, like hypertension, atherosclerosis and endothelial dysfunction. Experimental and clinical studies show a markedly rise in the oxidative stress biomarkers after menopause. Although many experimental works report beneficial effects of hormonal replacement with estrogen (E2) in the reduction of cardiovascular diseases risk, the results of clinical studies are so far to be conclusive about the use of this therapy as exclusive indication to prevent and treat cardiovascular diseases. In this context, lifestyle modifications are necessary, as the incorporation of regular physical activity. Many studies have demonstrated that physical training can positively influence on the main cardiovascular risk factors, including in postmenopausal women. The aim of this study is to analyze the effects of chronic physical training through swimming and the estrogen therapy in the vascular reactivity of coronary bed of ovariectomized rats, and the role of antioxidant enzymes expression in these responses. The female rats were divided in five groups following ovariectomy: SHAM, ovariectomized (OVX), ovariectomized treated with E2 (OTRH), Ovariectomized trained (OEX) and ovariectomized treated with E2 plus exercise (OTREX). E2 replacement was performed by injection s.c. containing 5 µg of 17βEstradiol, three times a week. The training was conducted by continuous swimming training, sixty minutes daily and five times per week. Both training and therapy started seven days after ovariectomy and lasted eight weeks. Forty eight hours after the last treatment and/or training session, the animals were sacrificed to carry out two different protocols of analysis. For the functional study with isolated hearts we evaluated the effects of treatments on bradykinin-mediated dilation, and for the assessment of antioxidant enzymes expression was performed dissection of the coronary arteries. The results demonstrated that both exercise and E2 can modulate the body composition. The endothelium-dependent vasodilator response was improved in all groups compared to OVX in the highest concentration (1000 ng), however, it was more pronounced in the OEX group which was significantly higher in the three highest concentrations. In relation to antioxidant enzymes, SOD-1 increased in the three experimental groups compared to OVX. Catalase was increased only in the OEX group compared to OVX and glutathione peroxidase decreased in all groups compared to SHAM. The eNOS expression was significantly higher in the OEX group in relation to OTRH, while iNOS was decreased in this same group compared to SHAM. Thus, according to the results of the present study, we can conclude that both training and E2 treatment may play a role in the cardioprotection and the practice of physical training can be a feasible alternative in relation to estrogen therapy in post-menopausal women.