大鼠不同部位骨骼对外源性甲状腺激素反应性的研究

目的：用左旋甲状腺素（L－T4）制备实验性甲状腺功能亢进（甲亢）大鼠模型，以探讨甲亢大鼠的胫骨和椎骨对外源性甲状腺激素的反应性，为临床监测长期L-T4治疗提供依据。方法：9周龄雄性Sprague-Dawley(SD)大鼠18只，随机分为甲亢组11只、对照组7只。甲 亢组予L－T4腹腔内注射，对照组予生理盐水注射，连续注射3周后取大鼠的胫骨近端、第四腰椎用非脱钙骨组织形态学计量法进行同期观察和研究。结果：在胫骨甲亢组的骨小梁数量降低，骨形成表面、吸收表面均增加，但骨吸收表面增加更明显，骨小梁平均宽度、骨纵向生长率降低，而骨矿化率增加。椎骨未观察到此变化。结论：L－T4引起继发性胫骨骨量减少，骨转换增加，椎骨无反应，表明不同部位的骨骼对甲状腺激素的反应存在异质性。

Responses in different skeletal sites of the rats to exogenous thyroid hormone

Objective:To determine the skeletal response in different sites to exogenous thyroid hormone in rat models of hyperthyroidism by administrating levo thyroxine(L T₄) Methods:18 male Sprague Dawley (SD) rats of 9 weeks old were randomly divided into hyperthyroid group (n=11) and control group (n=7).After 3 weeks of L T₄ treatment of hyperthyroid group,histomorphometric parameters of trabecular bone remodeling were assessed in the proximal tibia and in the fourth vertebra.Results:In tibia,trabecular bone volumes,mean trabecular thickness,and longtitudinal bone growth rate were decreased,trabecular formation surfaces and resorption surfaces increased significantly.Whereas these change were not apparent in the vertebra.Conclusion:It is concluded that L T₄ caused secondary bone loss,in tibia,associated with increased bone turnover.There exists some heterogeneity in the different parts of skeleton in response to thyroid hormone.