Chen D, Waite L C, Pierce W M
Department of Pharmacology & Toxicology, University of Louisville School of Medicine, KY 40292, USA.
Biol Trace Elem Res. 1999 Jun;68(3):225-34. doi: 10.1007/BF02783905.
Zinc deficiency is associated with a reduced rate of bone formation that can be corrected by supplementation of the deficient diet with adequate amounts of zinc. This study was conducted to examine the effects of zinc on bone cell parameters associated with bone formation. Tibiae were removed from 19-d-old chicken embryos and incubated for 48 h in Dulbecco's modified Eagle's medium supplemented with antibiotics, bovine serum albumin, and HEPES. The addition of zinc (25-200 g/dL) to tibial cultures resulted in a concentration-dependent increase in alkaline phosphatase activity, an increase in the incorporation of proline into bone protein and an increase in the post-translational oxidation of proline to peptidyl hydroxyproline. These effects of zinc were all diminished by the addition of 2,6-pyridine dicarboxylic acid, a chelator of zinc. The addition of either cycloheximide (10(-5)M), dactinomycin (10(-8)M), or hydroxyurea (10(-3)M) to tibial cultures also attenuated the effects of zinc. The effect of zinc on bone cell DNA synthesis was measured by following the incorporation of 3H-thymidine into DNA and by fluorometric measurement of cellular DNA content. These methods revealed that the addition of zinc to cultured tibiae resulted in a concentration-dependent increase in tibial DNA content and synthesis rate. The magnitude of the zinc-induced DNA increase was similar to the magnitude of the zinc-induced increases in alkaline phosphatase activity, proline incorporation, and hydroxyproline synthesis. Normalization of these latter responses to tibial DNA content yield data indicating that the effect of zinc on bone formation results from a zinc-induced increase in bone cell proliferation.
锌缺乏与骨形成速率降低有关，通过在缺乏锌的饮食中补充适量的锌可以纠正这种情况。本研究旨在探讨锌对与骨形成相关的骨细胞参数的影响。从19日龄鸡胚中取出胫骨，在补充了抗生素、牛血清白蛋白和HEPES的杜尔贝科改良伊格尔培养基中孵育48小时。向胫骨培养物中添加锌（25 - 200μg/dL）导致碱性磷酸酶活性呈浓度依赖性增加，脯氨酸掺入骨蛋白增加，以及脯氨酸翻译后氧化为肽基羟脯氨酸增加。锌的这些作用都因添加锌螯合剂2,6 - 吡啶二羧酸而减弱。向胫骨培养物中添加放线菌酮（10⁻⁵M）、更生霉素（10⁻⁸M）或羟基脲（10⁻³M）也减弱了锌的作用。通过追踪³H - 胸腺嘧啶掺入DNA以及通过荧光法测量细胞DNA含量来测量锌对骨细胞DNA合成的影响。这些方法表明，向培养的胫骨中添加锌导致胫骨DNA含量和合成速率呈浓度依赖性增加。锌诱导的DNA增加幅度与锌诱导的碱性磷酸酶活性、脯氨酸掺入和羟脯氨酸合成增加幅度相似。将这些后一种反应归一化为胫骨DNA含量得到的数据表明，锌对骨形成的影响源于锌诱导的骨细胞增殖增加。
