镉染毒大鼠胫骨骨微结构的活体Micro-CT观察

Micro-CT analysis of the tibia microstructure in live male rats exposed to cadmium

目的应用Micro-CT研究不同剂量CdCl2染毒后大鼠胫骨松质骨骨小梁密度和骨微结构的差异。方法 24只3月龄雄性SD大鼠随机分成4组,对照组、低剂量组、中剂量组和高剂量组,分别背部皮下注射生理盐水(0.5 mL)和0.1、0.5、1.5 mg/(kg.bw)CdCl2,每周称体重,并根据体重调整注射量。染毒后第8周对所有大鼠左侧胫骨近端进行活体Micro-CT扫描及三维重建。选取距生长板远端0.8、1.2 mm厚的骨组织为感兴趣区域,进行骨形态计量分析。结果镉染毒组大鼠体重和对照组相比有不同程度下降,高剂量组和其他组相比差异有显著性(P<0.05);镉染毒组大鼠骨密度、骨体积分数及骨小梁数量较对照组明显减少,高剂量组与对照组相比差异有显著性(P<0.01);镉染毒组大鼠胫骨骨小梁分离度及骨结构模型指数都较对照组有明显增高,并且随着染毒剂量的增加而升高。二维及三维图象显示,镉作用后大鼠胫骨骨髓腔增宽,骨量、骨小梁数量及骨小梁连接明显减少,板状骨数量减少,杆状骨数量增加。结论镉染毒对大鼠胫骨骨量及骨微观结构有明显损害。

Objective To investigate the effects of cadmium on bone microstructure in live male rats by micro-CT imaging.Methods Twenty-four 3-month-old Sprague-Dawley male rats were randomly divided into 4 groups which were given CdCl2 by subcutaneous injection at a doses of 0（sodium chloride）,0.1,0.5 and 1.5 mg/kg body weight,respectively.At the 8th week,micro-CT analysis was performed on the proximal tibia for bone microstructure evaluation.Trabecular bone was reconstructed and selected for analysis within a conforming volume of interest（cortical bone excluded） commencing at a distance of 0.8 mm from the growth plate,and extending a further longitudinal distance of 1.2 mm in the distal direction.Results The body weights of cadmium-treated rats were all lower than that in the controls.The volumetric bone mineral density of cadmium-treated rats at the dose of 1.5 mg/kg bw was significantly lower than that of rats treated with sodium chloride（P0.05）.Bone microstructure index（bone fraction volume,trabecular number） and trabecular separation of rats treated with cadmium at 1.5 mg/kg bw were significantly lower and significantly higher than that in the controls（P0.01）,respectively.Structure model index of cadmium-treated rats was obviously larger than that in the controls.2-dimensional and 3-dimensional images also revealed the damages of bone microstructure（trabecular conjunction points decreased and dissociated ends increased） caused by cadmium exposure.Conclusions These observations provide an interpretation for cadmium damaging effects on bone from structural viewpoint.Cadmium can induce bone microstructure damage,especially to trabecular bone.