Efeitos do exercício físico sobre propriedades estruturais e mecânicas do fêmur de ratos com diabetes experimental e sob insulinoterapia

• Autor(a) principal: Gomes, Gilton de Jesus
• Data de Publicação: 2013
• Tipo de documento: Dissertação
• Idioma: por
• Título da fonte: LOCUS Repositório Institucional da UFV
• Texto Completo: http://locus.ufv.br/handle/123456789/3488
• topic: Diabetes; Exercício físico; Tecido ósseo; Diabetes; Exercise; Bone tissue; CNPQ::CIENCIAS DA SAUDE::EDUCACAO FISICA

The aim of this study was to investigate the effects of a low-intensity swimming training (ST) combined with insulin therapy on the femoral structural and mechanical properties in growing rats with experimental type 1 diabetes mellitus (T1DM) induced by streprozotocin (STZ). Sixty Wistar rats at 30 days of age and average body mass of 90g at the onset of the experiment were used. The animals were randomized into six groups of ten animals: sedentary control (CS), exercised control (CE), diabetic sedentary (DS) and diabetic exercised (DE), sedentary diabetic treated with insulin (DSI), insulin-treated diabetic exercised (DEI). The animals from DE, DS, DEI and DSI groups received an intraperitoneal injection (60 mg/kg body weight) of STZ diluted in 1 mL of sodium citrate buffer (0.1M, pH 4.5). Seven days after the STZ injection and 12 hours fasting animals showing blood glucose above 300 mg/dL were considered diabetic. Seven days after induction of diabetes, the animals in group DE, DEI and CE were subjected to swimming training (90 min/day; 5 days/week; 5% body weight) for eight weeks. For the same period animals from groups and DEI and DSI received a daily dose of human insulin (1-4 U/day). By the end of the experimental period, animals were euthanized and the right femur was dissected for assessment of bone mineral density (BMD), bone mineral content (BMC) and bone strength. The left femur was dissected for determination of bone morphometry. The results showed that the experimental T1DM reduced femoral BMC and BMD, femoral neck stiffness, breaking force, tenacity, bone volume, total collagen and type III collagen content. In the femoral midshaft T1DM reduced bone breaking force, stiffness and the cortical thickness. The insulin therapy itself attenuated the deleterious effects of T1DM on the femoral BMC and BMD; and mittigated the reductions of bone breaking force and tenacity as well as reversed the trabecular bone volume loss and the total collagen content in the femoral neck. In the femoral midshaft region insulin therapy attenuated the reductions in bone stiffness, breaking force, tenacity and cortical bone thickness. Swimming training itself increased the femoral BMD, the femoral neck trabecular bone volume, and the midshaft tenacity in control rats (CE group) as well as the femoral neck breaking force and tenacity in diabetic animals non treated with insulin (DE group). The combination of ST with insulin therapy increased the femoral neck trabecular bone volume and breaking force in diabetic animals (DEI group). It was concluded that the combination of low-intensity swimming training with insulin therapy is effective in attenuating the deleterious effects of experimental T1DM induced by STZ on the femoral structural and mechanical properties in growing rats.