Effects of different aerobic exercise frequencies on streptozotocin–nicotinamide‐induced type 2 diabetic rats: Continuous versus short bouts and weekend warrior exercises

Background Exercise training is known to have multiple beneficial effects on type 2 diabetes mellitus (T2DM). The aim of this study was to explore the effects of aerobic exercise frequency on diabetic parameters, the histopathological structure of skeletal muscle, diabetic myopathy, and mitochondrial enzyme activity in an experimental model of T2DM. Methods Sprague‐Dawley rats (n = 35) were rendered diabetic by injection of nicotinamide (110 mg/kg) and streptozotocin (65 mg/kg). Rats with blood glucose concentrations between 7 and 17 mmol/L were used. Diabetic rats were randomly allocated to one of the following groups: (i) control sedentary; (ii) diabetic sedentary; (iii) diabetic with continuous exercise (30 min/day, 5 days/week); (iv) diabetic with short bouts of exercise (3 × 10 min/day, 5 days/week); and (v) diabetic rats as “weekend warriors” (35 + 40 min/day, 2 days/week). After 6 weeks swimming exercise (total duration 150 min/week), biochemical tests were performed to measure insulin, glucose, cytokines, serum and muscle myeloperoxidase (MPO), and malondialdehyde (MDA) levels. Histologic analysis (histomorphometric and mitochondrial enzyme analysis) was also performed. Results Compared with diabetic sedentary rats, significant improvements were observed in all exercise groups in terms of glucose levels, weight loss, tissue MPO and MDA levels, muscular connective tissue, muscle atrophy, mitochondrial enzyme, and all histomorphometric analyses. Conclusions The results of the study emphasize the effects of training on inflammation, increased oxidative stress, myopathy, and mitochondrial damage in a rat model of T2DM, and demonstrate that there is no major difference between exercise modalities provided that the total duration of exercise remains the same. 摘要 背景 目前已经知道运动锻炼对2型糖尿病具有多种有益的影响。本研究旨在一个实验性的2型糖尿病模型中探讨有氧运动频率对糖尿病参数、骨骼肌组织病理学结构、糖尿病肌病以及线粒体酶活性的影响。 方法 通过给Sprague‐Dawley大鼠(n = 35)注射烟酰胺(110 mg/kg)与链脲霉素(65 mg/kg)建立糖尿病模型。实验所用的大鼠血糖浓度介于7与17 mmol/L之间。糖尿病大鼠被随机分配到以下任意一组:(i)不参与运动的对照组;(ii)不参与运动的糖尿病组;(iii)糖尿病持续运动组(30分钟/日, 5日/周);(iv)糖尿病短时间运动组(3×10分钟/日, 5日/周);以及(v)糖尿病大鼠“周末战士”运动组(35+40分钟/日, 2日/周)。经过6周的游泳运动(每周总运动持续时间为150分钟)后, 对大鼠进行生化检验, 分别测定了胰岛素、葡萄糖、细胞因子、血清与肌髓过氧化物酶(myeloperoxidase, MPO)、以及丙二醛(malondialdehyde, MDA)的水平, 并进行了组织学分析(组织形态学与线粒体酶分析)。 结果 与糖尿病久坐组大鼠相比, 在所有的运动组中都能够观察到葡萄糖水平、体重、组织MPO与MDA水平、肌肉结缔组织、肌肉萎缩、线粒体酶以及所有的组织形态学分析结果都有显著性的改善。 结论 这项研究结果凸显了锻炼对2型糖尿病大鼠模型存在的炎症、增加的氧化应激、肌病以及线粒体损伤的影响, 研究结果还表明, 各种运动模式之间在保持总的运动时间相同下没有太大的区别。 Highlights The findings of the prese