Protein undernutrition-induced bone loss is associated with decreased IGF-I levels and estrogen deficiency
Protein undernutrition-induced bone loss is associated with decreased IGF-I levels and estrogen deficiency
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DOI：
10.1359/jbmr.2000.15.4.683
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发表时间：
2000-04-01
影响因子：
6.2
通讯作者：
Rizzoli, R
中科院分区：
文献类型：
--
作者：
Ammann, P;Bourrin, S;Rizzoli, R
蛋白质营养不良是老年人骨质疏松性骨折发病机制中的一个已知因素，但这种缺乏导致的骨丢失机制仍然知之甚少。我们研究了不同蛋白质含量水平（15%、7.5%、5%和2.5%酪蛋白）的四种等热量饮食对成年雌性大鼠骨密度（BMD）、骨极限强度、组织形态计量学、骨重建生化标志物、血浆IGF-I和性激素状态的影响。16周后，2.5%的酪蛋白饮食，骨密度显着下降，在骨骼部位含有骨小梁或皮质骨。血浆IGF-I降低29-34%，阴道涂片未见发情迹象。为了研究雌激素缺乏和蛋白质营养不良的作用，在卵巢切除（OVX）或假手术（SHAM）大鼠中使用相同的协议，成对喂养含15或2.5%酪蛋白的等热量饮食。小梁骨密度下降，无论是操作，效果似乎是加性的。皮质骨密度下降，只有在大鼠的低蛋白饮食。这伴随着尿脱氧吡啶啉排泄增加，而骨钙素水平无任何变化，表明再吸收和形成之间的解偶联。等热量蛋白质营养不良降低骨矿物质质量和强度。这种效应可能与血浆IGF-I降低和/或雌激素缺乏有关，从而导致骨重建失衡。
Protein undernutrition is a known factor in the pathogenesis of osteoporotic fracture in the elderly, but the mechanisms of bone loss resulting from this deficiency are still poorly understood. We investigated the effects of four isocaloric diets with varying levels of protein content (15, 7.5, 5, and 2.5 % casein) on areal bone mineral density (BMD), bone ultimate strength, histomorphometry, biochemical markers of bone remodeling, plasma IGF-I, and sex hormone status in adult female rats. After 16 weeks on a 2.5% casein diet, BMD was significantly decreased at skeletal sites containing trabecular or cortical bone. Plasma IGF-I was decreased by 29-34% and no estrus sign in vaginal smear was observed. To investigate the roles of estrogen deficiency and protein undernutrition, the same protocol was used in ovariectomized (OVX) or sham-operated (SHAM) rats, pair-fed isocaloric diets containing either 15 or 2.5% casein. Trabecular BMD was decreased by either manipulation, with effects appearing to be additive. Cortical BMD was decreased only in rats on a low-protein diet. This was accompanied by an increased urinary deoxypyridinoline excretion without any change in osteocalcin levels, suggesting an uncoupling between resorption and formation. Isocaloric protein undernutrition decreased bone mineral mass and strength. This effect might be related to decreased plasma IGF-I and/or estrogen deficiency with a consequent imbalance in bone remodeling.