Efeito do treinamento físico e da restrição alimentar na função cardíaca e resistência à insulina em ratos obesos / Effect of exercise training and food restriction in the cardiac function and insulin resistance in obese rats

AUTOR(ES)
DATA DE PUBLICAÇÃO

2009

RESUMO

BACKGROUND. Obesity is associated with cardiac function and hepatic fat metabolism abnormalities. On the other hand, exercise training and food restriction are known to restore obesity metabolic disorders and improve prognosis in obese individuals. However, whether these interventions improve cardiac function and its molecular mechanism associated with Ca2+ handling proteins are little unknown. The aims of this study were to investigate the effects of exercise training and food restriction on: 1) cardiac function and molecular net Ca2+ handling proteins in obese rats; 2) liver fat content in obese rats. In addition, we investigated whether the association of these two interventions had an additive effect on those responses. METHODS: Male Wistar rats (30 days-old) were fed with standard chow or cafeteria diet with high-fat for 25 weeks. At 25th week, the cafeteria diet rats were randomly assigned into 4 groups followed by 10 weeks: high-fat-chow (GO); high-fat-chow submitted to running exercise training (60% VO2peak, GOTF); food restriction (20% less intake of standard chow, GORA); and exercise training and food restriction (GOTFRA). Control rats continued fed with standard chow (GM). Hepatic insulin resistance was evaluated by HOMA-IR index (Homeostastic Metabolic Assessement- Insulin Resistance), liver fat content by liver triglyceride level, cardiac function was evaluated by echocardiography, M Modus and Tissue Doppler, and protein expression by Western blotting. RESULTS: Obese rats had increased body weight, adiposity index, HOMA-IR, glucose, leptin, epinephrine and norepinephrine levels and decreased left ventricular fractional shortening (39±1 vs 44±1%, P<0.05), ryanodine receptor phosphorylation (P-RyR-Ser2808/RyR , 52±7 vs 100±16%, P<0.01), phospholamban phosphorylation (P-PLB-Tre17/PLB, 76±6 vs 100±6%, P<0.05), nitrate level and reduced/oxidized glutathione ratio when compared with lean rats. Exercise training, food restriction or both decreased adiposity index, leptin, epinephrine and norepinephrine levels and increased left ventricular fractional shortening (41±1, 42±1 e 43±1%, respectively), ryanodine receptor phosphorylation (80±9, 79±7 and 66±12 %, respectively), phospholamban phosphorylation (107±9, 109±4 e 122±11%, respectively), nitrate level and reduced /oxidized glutathione ratio. Exercise training increased peak oxygen uptake. Food restriction alone or associated with exercise training decreased body weight and liver triglyceride level (GORA= -52 e GORATF= -63%). Neither exercise training nor food restriction restored HOMA-IR or glucose level. COCLUSIONS: Body weight reduction by exercise training or food restriction during 10 weeks prevents abnormalities in left ventricular systolic function associated with cardiac Ca2+ handling proteins expression in obese rats. Body weight reduction by these two interventions decreases steatosis without normalized HOMA-IR and glucose levels. Exercise training associated with food restriction does not have synergic effects on cardiac function and molecular net Ca2+ handling proteins, and liver fat content.

ASSUNTO(S)

fígado gorduroso função cardíaca exercício caloric restriction restrição calórica obesidade cardiac function fatty liver exercise obesity

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