Department of Medical Technology, University of Oulu, P.O. Box 5000, 90014 University of Oulu, Finland.
J Biomech. 2010 Apr 19;43(6):1097-103. doi: 10.1016/j.jbiomech.2009.12.011. Epub 2010 Feb 4.
Dioxins are known to decrease bone strength, architecture and density. However, their detailed effects on bone material properties are unknown. Here we used nanoindentation methods to characterize the effects of 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) on nanomechanical behaviour of bone matrix. Pregnant rats were treated with a single intragastric dose of TCDD (1 microg/kg) or vehicle on gestational day 11. Tibias of female offspring were sampled on postnatal day (PND) 35 or 70, scanned at mid-diaphysis with pQCT, and evaluated by three-point bending and nanoindentation. TCDD treatment decreased bone mineralization (p<0.05), tibial length (p<0.01), cross-sectional geometry (p<0.05) and bending strength (p<0.05). Controls showed normal maturation pattern between PND 35 and 70 with decreased plasticity by 5.3% and increased dynamic hardness, storage and complex moduli by 26%, 13% and 12% respectively (p<0.05), while similar maturation was not observed in TCDD-exposed pups. In conclusion, for the first time, we demonstrate retardation of bone matrix maturation process in TCDD-exposed animals. In addition, the study confirms that developmental TCDD exposure has adverse effects on bone size, strength and mineralization. The current results in conjunction with macromechanical behaviour suggest that reduced bone strength caused by TCDD is more associated with the mineralization and altered geometry of bones than with changes at the bone matrix level.
二恶英已知会降低骨强度、结构和密度。然而，其对骨基质特性的详细影响尚不清楚。在这里，我们使用纳米压痕方法来研究 2,3,7,8-四氯二苯并对二恶英（TCDD）对骨基质纳米力学行为的影响。妊娠大鼠在第 11 天经胃内给予 TCDD（1μg/kg）或载体单次剂量。在产后第 35 天或第 70 天取雌性后代的胫骨，用 pQCT 在骨干中部扫描，并进行三点弯曲和纳米压痕测试。TCDD 处理降低了骨矿化（p<0.05）、胫骨长度（p<0.01）、横截面几何形状（p<0.05）和弯曲强度（p<0.05）。对照组在 PND 35 至 70 之间表现出正常的成熟模式，塑性降低 5.3%，动态硬度、储存和复合模量分别增加 26%、13%和 12%（p<0.05），而 TCDD 暴露的幼崽则没有观察到类似的成熟。总之，这是首次证明 TCDD 暴露动物的骨基质成熟过程受到延迟。此外，该研究证实，发育性 TCDD 暴露对骨大小、强度和矿化有不良影响。目前的结果结合宏观力学行为表明，TCDD 引起的骨强度降低与骨矿化和骨骼几何形状的改变有关，而不是与骨基质水平的变化有关。
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