Soskolne W A, Schwartz Z, Goldstein M, Ornoy A
Dept. of Periodontics, Hebrew University Hadassah, Faculties of Dental Medicine and Medicine, Jerusalem, Israel.
Bone. 1990;11(5):301-7. doi: 10.1016/8756-3282(90)90084-c.
To examine the effects of T3 on fetal long bone modelling the radii and ulnae of 16 day old fetal mice were grown in vitro for two days. Their growth, mineralization, and resorption were assessed by measuring diaphyseal length, calcium and phosphorus content, hydroxyproline content, and the release of incorporated 45Ca. The effects of T3 were compared to the effects of 1-34 PTH, a known resorbing agent, on the same system. Devitalized bones were used as a control. The results showed that T3 had a biphasic effect. At high concentrations (10(-5) M-10(-6) M) T3 inhibited the growth of the bones as indicated by their diaphyseal length and hydroxyproline content. Calcium and phosphorus content were significantly decreased while 45Ca release was increased. Similar effects were also found after the addition of 1-34 PTH to the media. However, T3, at lower concentrations (10(-7) M-10(-9) M), stimulated the growth and calcification of the bones as indicated by an increase in diaphyseal length and the hydroxyproline, calcium, and phosphorus content. 45Ca release was significantly decreased at these concentrations. Neither T3 nor 1-34 PTH affected devitalized bones in the same system. The results suggest that at physiological concentrations, T3 has a direct, anabolic effect on bone, which may explain its major role in the growth process of various species. At high doses, however, T3 stimulates bone resorption in a way similar to PTH.
为研究T3对胎儿长骨塑形的影响，将16日龄胎儿小鼠的桡骨和尺骨进行体外培养两天。通过测量骨干长度、钙和磷含量、羟脯氨酸含量以及掺入的45Ca释放量来评估其生长、矿化和吸收情况。将T3的作用与已知的吸收剂1-34 PTH在同一系统中的作用进行比较。将失活的骨骼用作对照。结果表明，T3具有双相作用。在高浓度（10(-5)M - 10(-6)M）时，T3抑制骨骼生长，这可通过骨干长度和羟脯氨酸含量来表明。钙和磷含量显著降低，而45Ca释放增加。在培养基中添加1-34 PTH后也发现了类似的作用。然而，在较低浓度（10(-7)M - 10(-9)M）时，T3刺激骨骼生长和钙化，这可通过骨干长度以及羟脯氨酸、钙和磷含量的增加来表明。在这些浓度下，45Ca释放显著降低。在同一系统中，T3和1-34 PTH均未影响失活的骨骼。结果表明，在生理浓度下，T3对骨骼具有直接的合成代谢作用，这可能解释了它在各种物种生长过程中的主要作用。然而，在高剂量时，T3以类似于PTH的方式刺激骨吸收。
