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Somatomedin C in protein and amino acid nutrition

生长调节素 C 在蛋白质和氨基酸营养中的应用

基本信息

批准号：
62560073
负责人：
NOGUCHI Tadashi
金额：
$ 1.34万
依托单位：
The University of Tokyo
依托单位国家：
日本
项目类别：
Grant-in-Aid for General Scientific Research (C)
财政年份：
1987
资助国家：
日本
起止时间：
1987 至 1989
项目状态：
已结题

项目摘要

Somatomedin C (or insulin-like growth factor-I, IGF-I) is a peptide hormone, the structure of which is known to be similar to insulin. However, IGF-I shows biological properties distinct from insulin. IGF-I has been elucidated to be produced mainly by liver under the control of growth hormone and nutritional status of animals. However, the effect of dietary proteins has not been studied extensively. This work was plained to elucidate the effect of dietary proteins on plasma immunoreactive (ir) IGF-I concentration, the mode of association of IGF-I with plasma IGF-binding proteins, and the correlation between plasma ir-IGF-I concentration and whole body protein synthesis rate.Nutritional quality of dietary proteins affected plasma ir-IGF-I extensively. The rats fed a casein diet showed the highest ir-IGF-I concentration and those given a protein- free diet, the lowest. Plasma ir-IGF-I of rats fed a gluten or corn gluten weal diet showed the intermediate values. Supplementation of lysine and threonine to the gluten diet or tryptophan and lysine to the corn gluten meal diet increased plasma ir-IGF-I concentration significantly.Nutritional value of dietary proteins also affected the mode of association of IGF-I with IGF-binding proteins. IGF-I in the plasma of rats fed casein diet was found primarily in the 150 kDa fraction. However, significantly lower amount of IGF-I was found in this fraction in the rats given the protein-free diet.The rats fed the protein-free diet contained lower amount of IGF-I-mRNA in liver compared with those fed the casein diet.These results clearly show the important role of IGF-I in protein or amino acid nutrition of man and other animals.

生长抑素C(又称胰岛素样生长因子-I，IGF-I)是一种多肽类激素，其结构与胰岛素相似。然而，IGF-I显示出与胰岛素不同的生物学特性。目前已阐明IGF-I主要由肝脏在生长激素和动物营养状态的调控下产生。然而，膳食蛋白质的作用还没有得到广泛的研究。本研究旨在阐明日粮蛋白质对血浆Ir-IGF-I浓度的影响，IGF-I与血浆IGF结合蛋白的结合方式，以及Ir-IGF-I浓度与全身蛋白质合成率的相关性。饲喂酪蛋白饲料的大鼠表现出最高的ir-IGF-I浓度，而那些给予无蛋白饮食的大鼠的ir-IGF-I浓度最低。饲喂面筋蛋白或玉米面筋蛋白饲料的大鼠血浆ir-IGF-I呈中间值。在面筋蛋白日粮中添加赖氨酸和苏氨酸或在玉米蛋白粉日粮中添加色氨酸和赖氨酸显著提高血浆Ir-IGF-I浓度。日粮蛋白质的营养价值也影响IGF-I与IGF结合蛋白的结合方式。饲喂酪蛋白饲料的大鼠血浆中的IGF-I主要存在于150 kDa组分。然而，给予无蛋白饲料的大鼠肝脏中IGF-I的含量明显低于饲喂酪蛋白饲料的大鼠，这些结果清楚地表明了IGF-I在人和其他动物的蛋白质或氨基酸营养中的重要作用。