Robcis H L, Caldes T, de Pablo F
Diabetes Branch, National Institutes of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, Maryland 20892.
Endocrinology. 1991 Apr;128(4):1895-901. doi: 10.1210/endo-128-4-1895.
Insulin-like growth factor-I (IGF-I) is the primary mediator of GH action after birth, but its role as a regulator of prenatal growth is unclear. In a previous study we showed that IGF-I mRNA was expressed in chicken embryos beginning at the blastoderm stage (day 0, newly laid egg). Here we present the ontogeny of serum IGF-I in normal and growth-retarded chicken embryos. Serum samples were pooled from multiple embryos starting on day 4 of development in ovo until hatching (day 21). Extracts of day 2 and 3 whole embryos were also studied. IGF-binding proteins were removed by filtration on Sep-Pak C-18 cartridges. IGF-I was quantitated by a heterologous RIA validated for chicken species. Embryonic IGF-I showed a HPLC profile similar to that of adult chicken serum IGF-I. Serum IGF-I was measurable on day 6 of development (approximately 0.04 ng/ml), reached a peak on day 15 (18 ng/ml), and decreased to a low concentration (0.2 ng/ml) the day before hatching. Embryos cultured ex ovo showed progressive growth retardation after day 10 of development, and by day 20 their weight was 50% of normal. The serum IGF-I concentration of ex ovo cultured embryos was normal on day 10, but remained low until day 21, without the midembryogenesis rise observed in normal embryos. These results support the concept that IGF-I may have a role in general embryonic growth in addition to any paracrine/autocrine action in individual tissues.
胰岛素样生长因子-I（IGF-I）是出生后生长激素作用的主要介质，但其作为产前生长调节因子的作用尚不清楚。在先前的一项研究中，我们表明IGF-I mRNA从胚盘期（第0天，新产蛋）开始在鸡胚中表达。在此，我们展示正常和生长迟缓鸡胚中血清IGF-I的个体发生情况。从胚胎发育第4天开始直至孵化（第21天），收集多个胚胎的血清样本。还研究了第2天和第3天整个胚胎的提取物。通过在Sep-Pak C-18柱上过滤去除IGF结合蛋白。IGF-I通过经过鸡种验证的异源放射免疫分析法进行定量。胚胎IGF-I的高效液相色谱图与成年鸡血清IGF-I相似。血清IGF-I在发育第6天可检测到（约0.04 ng/ml），在第15天达到峰值（18 ng/ml），并在孵化前一天降至低浓度（0.2 ng/ml）。体外培养的胚胎在发育第10天后显示出逐渐的生长迟缓，到第20天时其体重仅为正常胚胎的50%。体外培养胚胎的血清IGF-I浓度在第10天时正常，但直到第21天一直保持较低水平，未出现正常胚胎中胚胎发育中期的升高现象。这些结果支持这样一种观点，即IGF-I除了在个体组织中具有旁分泌/自分泌作用外，可能在胚胎整体生长中发挥作用。
