Burch W M, Lebovitz H E
J Clin Invest. 1982 Sep;70(3):496-504. doi: 10.1172/jci110641.
We studied the effect of triiodothyronine (T3) on mammalian growth-plate cartilage in vitro. Growth-plate cartilages from fetal pigs scapulae were incubated for 3 to 7 d in serum-free medium alone or medium containing T3. Alkaline phosphatase activity, a marker of hypertrophied chondrocytes, was increased in T3 (10 nM)-treated growth-plate cartilage 152 +/- 36% above that of cartilage incubated in medium alone after 3 d of incubation, and 324 +/- 47% after 7 d of incubation. There was a dose-response increase in alkaline phosphatase activity to T3 over the range of 0.01-10 nM. The rise in alkaline phosphatase activity was specific for T3 since growth-plate cartilage alkaline phosphatase activity was not increased by cortisol, insulin, parathyroid hormone, or 5% fetal calf serum. Histological studies of growth-plate cartilage showed that T3 in a concentration-dependent manner increased the width of the zone of maturation (hypertrophied chondrocytes). Histochemical staining for alkaline phosphatase activity demonstrated that T3 caused the recruitment of new cells into the zone of maturation. T3 also stimulated incorporation of L-[3H]leucine into protein and 35SO4 into proteoglycan in growth-plate cartilage. In contrast, T3 did not increase alkaline phosphatase activity or radiolabeled precursor incorporation into nongrowth-plate scapular cartilage. These studies demonstrate that T3 directly stimulates maturation and, to a lesser degree, growth-related processes in fetal mammalian growth-plate cartilage.
我们在体外研究了三碘甲状腺原氨酸（T3）对哺乳动物生长板软骨的作用。将胎猪肩胛骨的生长板软骨在无血清培养基或含T3的培养基中孵育3至7天。碱性磷酸酶活性是肥大软骨细胞的标志物，在孵育3天后，用10 nM T3处理的生长板软骨中碱性磷酸酶活性比仅在培养基中孵育的软骨增加了152±36%，孵育7天后增加了324±47%。在0.01 - 10 nM范围内，碱性磷酸酶活性对T3呈剂量反应性增加。碱性磷酸酶活性的升高对T3具有特异性，因为皮质醇、胰岛素、甲状旁腺激素或5%胎牛血清不会增加生长板软骨碱性磷酸酶活性。生长板软骨的组织学研究表明，T3以浓度依赖性方式增加了成熟区（肥大软骨细胞）的宽度。碱性磷酸酶活性的组织化学染色表明T3促使新细胞进入成熟区。T3还刺激生长板软骨中L-[3H]亮氨酸掺入蛋白质以及35SO4掺入蛋白聚糖。相比之下，T3不会增加非生长板肩胛软骨中的碱性磷酸酶活性或放射性标记前体掺入。这些研究表明，T3直接刺激胎儿哺乳动物生长板软骨的成熟，并在较小程度上刺激与生长相关的过程。
