缺碘大鼠的骨发育障碍

Impairment of bone development in iodine-deficient rats

目的 研究碘缺乏对大鼠骨发育和骨转换的影响。方法 复制生长发育期碘缺乏大鼠动物模型 ,测定血清中TT3 、TT4、FT4含量 ,对股骨远端 2 /3进行骨计量学测定。结果 碘缺乏大鼠血清TT4、FT4含量显著下降 ,TT3 含量代偿性增加。碘缺乏大鼠骨小梁骨量较正常大鼠明显减少 ,骨小梁体积(TBV) /全部骨组织体积减少约 47% ,TBV/海绵骨体积减少约 3 5 % ,平均骨小梁板厚度减少约 3 6% ,骨小梁表面 /TBV较正常大鼠增加约 3 4% (P <0 .0 1) ,骨皮质平均厚度较正常组减少了 16% (P <0 .0 5 )。碘缺乏大鼠四环素单标记线占全部骨小梁表面的百分比、四环素双标记线占全部骨小梁表面的百分比、平均类骨质宽度、骨小梁类骨质表面占骨小梁表面的百分比、矿化沉积率和组织水平骨形成率均低于正常对照组 (P <0 .0 5或P <0 .0 1) ,矿化延迟时间 (P <0 .0 5 )和类骨质成熟时间 (P <0 .0 1)大于正常大鼠。结论发育期的骨骼对T4的缺乏非常敏感。T4降低时骨骼发育不良 ,骨小梁骨量减少 ,皮质骨的生长也受到影响。

Objective To study the effects of iodine-deficiency on bone development and bone turnover in rats. Methods Iodine-deficient rat model was established. Serum TT 3, TT 4 and FT 4 were measured. Quantitative bone histomorphometric parameters were analyzed at distal femur. Results In iodine-deficient rats TT 4 and FT 4 were significantly decreased than those in normal rats, TT 3 was a little higher than that in normal rats. In iodine-deficient rats trabecular bone volume (TBV) and thickness were decreased significantly, TBV/total bone tissue volume was decreased 47%, TBV/sponge bone volume was decreased 35%, mean trabecular plate thickness was decreased 36%, trabecular bone surface (TBS)/TBV was increased 34% (P<0.01), mean cortical bone thickness was decreased 16% (P<0.05). The dynamic data showed that in iodine-deficient rats tetracycline-labelled single line/TBS, tetracycline-labelled double lines/TBS, mean osteoid width, trabecular osteoid surface/TBS, mineralization apposition rate and tissue-based bone formation rate were all lower than those in normal rats (P<0.05 or P<0.01), mineralization lag time (P<0.05) and osteoid maturation period (P<0.01) were higher than normal. Conclusion T 4 may be more important for bone growth than T 3. With iodine-deficiency bone cortical width and trabecular bone volume were reduced and bone development was retarded. Osteoblast avtivity was decreased and osteoid mineralizing process was damaged in iodine-deficient rats.