Mohan S, Baylink D J
Jerry L Pettis Veterans Medical Center, Department of Medicine, Loma Linda, CA 92357, USA.
Endocrine. 1997 Aug;7(1):87-91. doi: 10.1007/BF02778070.
Because impaired bone formation is a major contributor to the pathogenesis of senile (type II) osteoporosis, and because insulin-like growth factors (IGFs) have been shown to be important stimulators of bone formation in vitro and in vivo, studies have been focused towards clarifying the role of IGF system in the age-related impairment in bone formation. To evaluate if changes in circulating and bone cell production of IGF binding protein (IGFBP)-4 and IGFBP-5 could contribute to age-related impairment in bone formation, the authors measured serum and skeletal levels of IGFBP-5, and serum levels of IGFBP-4 during aging. Circulating levels of IGFBP-4 increased with age, whereas that of IGFBP-5 declined with age. Serum IGFBP-4 and IGFBP-5 levels showed significant positive correlations with serum levels of parathyroid hormone (PTH) and IGFs, respectively. In addition, skeletal content of IGFBP-5 declined with age. The age-related changes in IGFBP-4 and IGFBP-5 production could contribute, in part, to the decrease in osteoblast cell proliferation and deficiency in bone formation.
由于骨形成受损是老年性（II型）骨质疏松症发病机制的主要因素，并且胰岛素样生长因子（IGFs）已被证明在体外和体内都是骨形成的重要刺激因子，因此研究一直集中在阐明IGF系统在与年龄相关的骨形成受损中的作用。为了评估胰岛素样生长因子结合蛋白（IGFBP）-4和IGFBP-5的循环水平及骨细胞生成变化是否会导致与年龄相关的骨形成受损，作者测量了衰老过程中IGFBP-5的血清和骨骼水平以及IGFBP-4的血清水平。IGFBP-4的循环水平随年龄增长而升高，而IGFBP-5的循环水平随年龄增长而下降。血清IGFBP-4和IGFBP-5水平分别与甲状旁腺激素（PTH）和IGFs的血清水平呈显著正相关。此外，IGFBP-5的骨骼含量随年龄增长而下降。IGFBP-4和IGFBP-5生成的年龄相关变化可能部分导致成骨细胞增殖减少和骨形成不足。
