Bhattacharyya M H, Whelton B D, Stern P H, Peterson D P
Biological, Environmental, and Medical Research Division, Argonne National Laboratory, IL 60439-4833.
Proc Natl Acad Sci U S A. 1988 Nov;85(22):8761-5. doi: 10.1073/pnas.85.22.8761.
Loss of bone mineral after ovariectomy was studied in mice exposed to dietary cadmium at 0.25, 5, or 50 ppm. Results show that dietary cadmium at 50 ppm increased bone mineral loss to a significantly greater extent in ovariectomized mice than in sham-operated controls. These results were obtained from two studies, one in which skeletal calcium content was determined 6 months after ovariectomy and a second in which 45Ca release from 45Ca-prelabeled bones was measured immediately after the start of dietary cadmium exposure. Furthermore, experiments with 45Ca-prelabeled fetal rat limb bones in culture demonstrated that Cd at 10 nM in the medium, a concentration estimated to be in the plasma of mice exposed to 50 ppm dietary Cd, strikingly increased bone resorption, from 27 +/- 2% (mean +/- SEM) 45Ca release in cultures with no added cadmium to 68 +/- 6% release in cultures containing cadmium (n = 4). These in vitro results indicate that cadmium may enhance bone mineral loss by a direct action on bone. Results of the in vivo studies are consistent with a significant role of cadmium in the etiology of Itai-Itai disease among postmenopausal women in Japan and may in part explain the increased risk of postmenopausal osteoporosis among women who smoke.
在暴露于0.25、5或50 ppm膳食镉的小鼠中研究了卵巢切除术后的骨矿物质流失情况。结果表明，50 ppm的膳食镉使去卵巢小鼠的骨矿物质流失增加的程度明显大于假手术对照组。这些结果来自两项研究，一项研究在卵巢切除术后6个月测定骨骼钙含量，另一项研究在开始膳食镉暴露后立即测量45Ca预标记骨骼中45Ca的释放。此外，对培养中的45Ca预标记胎鼠四肢骨骼进行的实验表明，培养基中10 nM的镉（估计该浓度存在于暴露于50 ppm膳食镉的小鼠血浆中）显著增加了骨吸收，从无添加镉的培养物中45Ca释放量的27±2%（平均值±标准误）增加到含镉培养物中的68±6%释放量（n = 4）。这些体外实验结果表明，镉可能通过对骨骼的直接作用增强骨矿物质流失。体内研究结果与镉在日本绝经后女性痛痛病病因中起重要作用一致，并且可能部分解释了吸烟女性绝经后骨质疏松风险增加的原因。
