Kikuchi K, Buonomo F C, Kajimoto Y, Rotwein P
Department of Medicine, Washington University School of Medicine, St. Louis, Missouri 63110.
Endocrinology. 1991 Mar;128(3):1323-8. doi: 10.1210/endo-128-3-1323.
We have investigated the expression of insulin-like growth factor-I (IGF-I) during ontogeny in the chick. IGF-I mRNA was first detectable in whole embryos on day 6, while serum IGF-I could be measured on day 9, the earliest time point examined. Serum IGF-I values rose 10-fold from about 3 ng/ml on day 10 to a prehatch peak of 30-35 ng/ml during days 15-17, and then declined to about 10 ng/ml at the time of hatching. On days 17 and 20 of incubation, IGF-I mRNA was detected in eye, skeletal muscle, and brain, but could not be found in liver or heart until after hatching. During the posthatch period, serum IGF-I rose from 10 ng/ml in the first week to 35-40 ng/ml during weeks 3-6, and liver IGF-I mRNA increased nearly 5-fold from weeks 1-7. The increases observed during weeks 1-3 correlated with a posthatch rise in serum GH from 21 to 37 ng/ml, although GH levels declined over the subsequent 4 weeks without an appreciable change in serum IGF-I values. By contrast, before embryonic day 12 no GH could be detected in the circulation, while IGF-I was 19 ng/ml on day 11. These observations suggest that there is both GH-dependent and GH-independent regulation of IGF-I gene expression in the chick, as has been found in mammals, and support the idea that IGF-I plays a role in chicken embryonic development.
我们研究了鸡个体发育过程中胰岛素样生长因子-I（IGF-I）的表达情况。在第6天，整个胚胎中首次可检测到IGF-I mRNA，而血清IGF-I则在第9天（检测的最早时间点）可以检测到。血清IGF-I值从第10天的约3 ng/ml上升了10倍，在第15 - 17天达到孵化前的峰值30 - 35 ng/ml，然后在孵化时降至约10 ng/ml。在孵化的第17天和第20天，在眼睛、骨骼肌和大脑中检测到IGF-I mRNA，但直到孵化后在肝脏或心脏中才检测到。在孵化后阶段，血清IGF-I从第一周的10 ng/ml上升到第3 - 6周的35 - 40 ng/ml，肝脏IGF-I mRNA从第1 - 7周增加了近5倍。在第1 - 3周观察到的增加与孵化后血清生长激素（GH）从21 ng/ml上升到37 ng/ml相关，尽管在随后的4周内GH水平下降，但血清IGF-I值没有明显变化。相比之下，在胚胎第12天之前，循环中检测不到GH，而在第11天IGF-I为19 ng/ml。这些观察结果表明，正如在哺乳动物中所发现的那样，鸡的IGF-I基因表达存在GH依赖性和GH非依赖性调节，并支持IGF-I在鸡胚胎发育中起作用的观点。
