a Department of Nutrition and Exercise Physiology, University of Missouri-Columbia, 204 Gwynn Hall, Columbia, MO 65211, USA.
b Research Service-Harry S. Truman Memorial Veterans Medical Center, Columbia, MO, USA.
Appl Physiol Nutr Metab. 2017 Aug;42(8):884-892. doi: 10.1139/apnm-2017-0077. Epub 2017 May 1.
An often-overlooked comorbidity of type 2 diabetes (T2D) is increased fracture risk. Since traditional T2D therapies focus solely on glucose homeostasis, there is an increased need for effective treatment strategies that improve both metabolic and bone health. The current study evaluated if previously reported protective effects of exercise (EX) on cortical bone geometry and biomechanical properties are due to the prevention of obesity compared with obese Otsuka Long-Evans Tokushima Fatty (OLETF) rats or the unique skeletal effects of exercise. Four-week-old male OLETF rats were randomly assigned to 1 of 3 groups, each fed a standard rodent chow diet until 40 weeks of age: ad libitum-fed sedentary (O-SED), ad libitum-fed EX (O-EX), or a control group body-weight-matched to the O-EX group by caloric restriction (O-CR). Ad libitum-fed sedentary Long-Evans Tokushima Otsuka (L-SED) rats were used as a lean control. EX or CR prevented the excess body mass accumulation and elevated HbA1c observed in O-SED. Total-body bone mineral density was greater in O-EX than O-CR, but similar to L-SED and O-SED. O-EX and O-CR had lower osteocalcin and TRAP5b than O-SED and L-SED. EX or CR prevented the ∼3-fold increase in CTx in O-SED versus L-SED. EX increased femoral cortical mass accumulation and expansion at the mid-diaphysis compared with O-CR. EX or CR significantly increased tissue-level stiffness and strength compared with O-SED and L-SED, but O-EX had greater whole-bone stiffness than all other groups. In summary, EX has distinct advantages over CR for improving bone biomechanical properties in hyperphagic OLETF rats.
2 型糖尿病（T2D）常伴有骨折风险增加，这一并发症常被忽视。由于传统的 T2D 治疗方法仅专注于血糖稳态，因此需要新的有效治疗策略来改善代谢和骨骼健康。本研究评估了之前报道的运动（EX）对皮质骨几何形状和生物力学特性的保护作用是否是通过预防肥胖与肥胖 Otsuka Long-Evans Tokushima Fatty（OLETF）大鼠相比，或者是运动的独特骨骼作用。4 周龄雄性 OLETF 大鼠随机分为 3 组，每组均喂食标准啮齿动物饲料，直至 40 周龄：自由进食久坐（O-SED）、自由进食 EX（O-EX）或通过热量限制与 O-EX 组体重匹配的对照组（O-CR）。自由进食久坐 Long-Evans Tokushima Otsuka（L-SED）大鼠作为瘦对照。EX 或 CR 可防止 O-SED 中观察到的体重过度增加和 HbA1c 升高。与 O-CR 相比，O-EX 的全身骨矿物质密度更高，但与 L-SED 和 O-SED 相似。与 O-SED 和 L-SED 相比，O-EX 和 O-CR 的骨钙素和 TRAP5b 水平较低。EX 或 CR 可防止 O-SED 与 L-SED 相比 CTx 增加约 3 倍。与 O-CR 相比，EX 增加了股骨皮质的质量积累和骨干中段的扩张。与 O-SED 和 L-SED 相比，EX 或 CR 显著增加了组织水平的刚度和强度，但 O-EX 的整体骨骼刚度大于其他所有组。总之，EX 对改善多食性 OLETF 大鼠的骨骼生物力学特性具有明显优于 CR 的优势。
