Lauterio T J, Scanes C G
Proc Soc Exp Biol Med. 1987 Sep;185(4):420-6. doi: 10.3181/00379727-185-42563.
Experiments were conducted to evaluate the possible role of circulating growth hormones triiodothyronine (T3), thyroxine (T4), and insulin-like growth factor I (somatomedin-C; IGF-I) in the elevation of plasma growth hormone (GH) which occurs in protein-restricted chickens. Plasma hormone changes were determined over a 2-week period of protein depletion by feeding a 5% protein diet as well as a similar period of protein repletion with a 20% protein diet. The rise in plasma GH was observed in two separate studies. Plasma concentrations of T4, T3, and IGF-I were all depressed in protein-restricted chicks prior to or concurrent with the GH elevation. In the protein repletion time course study, T4 and T3 concentrations were normalized prior to or concurrent with plasma GH normalization. However, IGF-I concentrations in repleted chicks did not return to control levels until after normal levels of GH were observed. These data suggest that thyroid hormones may play a greater role in the regulation of GH secretion during periods of malnourishment than IGF-I; the latter being currently thought to be a peripherally circulating inhibitor of GH release in animals.
开展实验以评估循环生长激素三碘甲状腺原氨酸（T3）、甲状腺素（T4）和胰岛素样生长因子I（生长调节素-C；IGF-I）在蛋白质限制型鸡血浆生长激素（GH）升高过程中可能发挥的作用。通过饲喂5%蛋白质日粮确定了为期2周的蛋白质消耗期以及用20%蛋白质日粮进行类似的蛋白质补充期内血浆激素的变化。在两项独立研究中观察到了血浆GH的升高。在蛋白质限制型雏鸡中，在GH升高之前或同时，T4、T3和IGF-I的血浆浓度均降低。在蛋白质补充时间进程研究中，在血浆GH恢复正常之前或同时，T4和T3浓度恢复正常。然而，直到观察到GH达到正常水平后，补充蛋白质的雏鸡中的IGF-I浓度才恢复到对照水平。这些数据表明，在营养不良期间，甲状腺激素在GH分泌调节中可能比IGF-I发挥更大作用；目前认为后者是动物体内GH释放的外周循环抑制剂。
