Efeitos do diabetes experimental sobre a morfologia e função do ventrículo esquerdo de ratos Wistar púberes: impacto do treinamento de natação

• Autor(a) principal: Silva, Edson da
• Data de Publicação: 2013
• Tipo de documento: Tese
• Idioma: por
• Título da fonte: LOCUS Repositório Institucional da UFV
• Texto Completo: http://locus.ufv.br/handle/123456789/268
• topic: Diabetes; Remodelamento ventricular; Exercício; Adiponectina; Diabetes; Ventricular remodeling; Exercise; Adiponectin; CNPQ::CIENCIAS BIOLOGICAS::BIOLOGIA GERAL

Diabetic cardiomyopathy is associated not only with cardiac remodeling and myocardial dysfunction but also with the occurrence of low-grade inflammation and reduced cardiac adiponectin resulting in significant morbidity and mortality in patients with type 1 diabetes mellitus (T1DM). On the other hand, physical exercise is an important strategy for the management of diabetes which can reduce inflammation and attenuate adverse cardiac remodeling and contractile dysfunction. The aim of this study was to investigate the influence of low-intensity swimming training on the structural remodeling, cardiac cytokines, inflammation, and cardiomyocyte contractile dysfunction of the left ventricle (LV) in pubescent rats with unmanaged experimental diabetes. Thirty-day-old male Wistar rats were divided into four groups (n = 19, per group): sedentary control (SC), exercised control (EC), sedentary diabetic (SD), and exercised diabetic (ED). Diabetes was induced by streptozotocin (STZ, 60 mg kg-1 body weight). Animals from EC and ED groups were submitted to a swimming training (5 days/week, 90 min/day, load of 5% body weight) for 8 weeks. After euthanasia LV was removed for molecular, morphological, and cardiomyocyte mechanical analysis. Sections of LV were stained with Periodic acid-Schiff (PAS), Sirius Red, Gomori s reticulin, Gomori's trichrome, and toluidine blue/sodium borate 1%. The LV of diabetic animals presented increased interstitial collagen and reticular fibers on the extracellular matrix, accumulation of glycogen, myocardial histoarchitectural disorganization, inflammatory infiltrate and necrosis. The capillary density was significantly lower in diabetic animals. Left ventricular cardiomyocytes from diabetic animals exhibited more prolonged time to the peak of contraction and the time to half relaxation than those from control animals, but no difference in cell shortening was observed. The cardiac levels of interleukin 10, nitric oxide, total and HMW adiponectin were significantly decreased in diabetic animals. Exercise training attenuated the level of TNF-α and the histopathological parameters assessed, and increased the capillary density in the LV of diabetic rats. In conclusion, the cardiac structural remodeling induced by experimental T1DM coexists with reduced levels of total and HMW adiponectin, chronic inflammation and cardiomyocyte contractility dysfunction. More important, low-intensity swimming training attenuated part of these pathological changes which indicate the beneficial role for regular exercise in untreated T1DM.