Sherk Vanessa D, Heveran Chelsea M, Foright Rebecca M, Johnson Ginger C, Presby David M, Ferguson Virginia L, MacLean Paul S
Department of Orthopedics, University of Colorado Anschutz Medical Campus, Aurora, CO, United States of America.
Department of Mechanical & Industrial Engineering, Montana State University, Bozeman, MT, United States of America.
Bone. 2021 Apr;145:115840. doi: 10.1016/j.bone.2021.115840. Epub 2021 Jan 6.
Bone fragility and obesity are both diseases that are multifactorial in etiology and pathology. The contributing role of high fat diet (HFD) versus energy overconsumption on bone health is controversial. Exercise is often prescribed for improving bone health, but it is unclear whether HFD or overconsumption influences skeletal adaptations to exercise. Female and male Wistar rats were fed HFD or low fat diet (LFD) for 10 weeks, starting at 8 weeks of age. Within HFD, rats were labeled Obesity-Resistant (OR) or Obesity-Prone (OP) based on weight and fat gain. Within each diet and phenotype group, rats were randomized to treadmill exercise or sedentary control (SED) for the final 4 weeks. Femurs were assessed for fracture toughness. Cortical lamellar and nonlamellar bone microscale material behavior and chemistry were assessed using nanoindentation and Raman spectroscopy. Female bones had higher fracture toughness and mineral: matrix ratio than male bones. Diet and energy overconsumption affected bone characteristics in a sex-dependent manner, where the divergence between OP and OR in response to HFD occurred more rapidly in males. Diet composition, in general, had a stronger effect on bone quality than overconsumption. HFD dramatically decreased bone size and lamellar mineral:matrix compared to LFD. Effects of short-term exercise training on microscale tissue properties were generally more robust with LFD. Exercise enhanced the contrast between lamellar and nonlamellar bone for nanoindentation modulus but decreased this contrast for plastic work. Our data demonstrate the complexities in the relationship between diet and obesity and highlight the importance of addressing both aspects when characterizing bone quality and fracture resistance.
骨脆性和肥胖都是病因和病理多因素的疾病。高脂肪饮食（HFD）与能量过度摄入对骨骼健康的作用存在争议。运动常被推荐用于改善骨骼健康，但尚不清楚HFD或过度摄入是否会影响骨骼对运动的适应性。从8周龄开始，将雌性和雄性Wistar大鼠分别喂食HFD或低脂饮食（LFD）10周。在HFD组内，根据体重和脂肪增加情况将大鼠分为抗肥胖（OR）或易肥胖（OP）。在每个饮食和表型组中，大鼠在最后4周被随机分为跑步机运动组或久坐对照组（SED）。评估股骨的断裂韧性。使用纳米压痕和拉曼光谱评估皮质板层骨和非板层骨的微观材料行为及化学成分。雌性骨骼的断裂韧性和矿物质与基质的比例高于雄性骨骼。饮食和能量过度摄入以性别依赖的方式影响骨骼特征，其中雄性对HFD的反应中OP和OR之间的差异出现得更快。一般来说，饮食组成对骨质量的影响比过度摄入更强。与LFD相比，HFD显著降低了骨大小和板层矿物质与基质的比例。短期运动训练对微观组织特性的影响在LFD组通常更强。运动增强了纳米压痕模量在板层骨和非板层骨之间的对比度，但降低了塑性功的对比度。我们的数据证明了饮食与肥胖关系的复杂性，并强调在表征骨质量和抗骨折能力时兼顾这两个方面的重要性。
