Nutting D F
Endocrinology. 1976 Dec;99(6):1423-31. doi: 10.1210/endo-99-6-1423.
The ability of GH in vitro to stimulate leucine incorporation into protein and the uptake of 2-aminoisobutyric acid (AIB) and 3-O-methyl-glucose (3-OMG) was studied in diaphragm muscle from dwarf (dw/dw) mice. Ovine GH (25 mug/ml) significantly enhanced the rate of protein synthesis in muscle from untreated dwarfs. In contrast, GH usually failed to stimulate transport, although occasionally a small increase in AIB uptake was seen. Insulin (50 muU/ml) readily stimulated both AIB transport and protein synthesis in muscle from untreated dwarfs. Dwarfs were treated for 4 days with thyroxine (T4) (0.3-5 mug/day) or 3,5,3'-triiodo thyronine (T3) (0.1 mug/day). This enhanced the responsiveness of the transport systems to GH and seemed to increase the basal transport rates for AIB and 3-OMG. After the T4-treatment 0.75 mug/ml GH stimulated AIB transport in mice aged 15 weeks; 25 mug/ml GH stimulated AIB transport in dwarfs aged 5 weeks-1 yr. and leucine incorporation into protein in dwarfs aged 5 weeks-2 yr. This last result suggests that response to GH does not cease merely due to increasing age. Synergism by T3/T4 was not permanent, and the maximum response to GH occurred 1 week after the last injection of T4. The possible mechanisms whereby thyroid hormones enhance responsiveness of the transport systems to GH are discussed.
研究了生长激素（GH）在体外刺激侏儒（dw/dw）小鼠膈肌中亮氨酸掺入蛋白质以及2-氨基异丁酸（AIB）和3-O-甲基葡萄糖（3-OMG）摄取的能力。绵羊生长激素（25微克/毫升）显著提高了未处理侏儒小鼠肌肉中蛋白质合成的速率。相比之下，生长激素通常无法刺激转运，尽管偶尔会观察到AIB摄取略有增加。胰岛素（50微单位/毫升）很容易刺激未处理侏儒小鼠肌肉中的AIB转运和蛋白质合成。用甲状腺素（T4）（0.3 - 5微克/天）或3,5,3'-三碘甲状腺原氨酸（T3）（0.1微克/天）对侏儒小鼠进行4天治疗。这增强了转运系统对生长激素的反应性，并且似乎提高了AIB和3-OMG的基础转运速率。T4治疗后，0.75微克/毫升的生长激素刺激15周龄小鼠的AIB转运；25微克/毫升的生长激素刺激5周龄至1岁侏儒小鼠的AIB转运，以及5周龄至2岁侏儒小鼠肌肉中亮氨酸掺入蛋白质。最后这个结果表明，对生长激素的反应不会仅仅因为年龄增长而停止。T3/T4的协同作用不是永久性的，对生长激素的最大反应发生在最后一次注射T4后1周。文中讨论了甲状腺激素增强转运系统对生长激素反应性的可能机制。
